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Thermostat Features/Specs

Display	Large, clear touchscreen
Program Features	7 day programming with 4 program periods per day can be configured to meet almost any scheduling scenario for ultimate flexibility
Thermostat Dimensions	6 x 1.5 x 5 inches, 14.1 ounces
Colors	White
Batteries	3032 Nonstandard Battery batteries required. (included)
WiFi	Internet-controlled thermostat, WiFi control through smartphone, laptop, or tablet.

91

INSTALLATION

90/100

EASE OF USE

100/100

OPTIONS

80/100

SCREEN

90/100

PRICE

95/100

Pros:

• – Large easy to use screen
• – WiFi Control from anywhere
• – Great price for Wifi Thermostat
• – Smart response technology
• – Filter change indicator

Cons:

• – Build quality feels average
• – Honeywell site loses connection sometimes

The Honeywell RTH8580WF WiFi Thermostat is a major contender in the WiFi thermostat market. Currently the most popular unit is the Nest Learning Thermostat, but it is expensive. What if you want a thermostat that will do most of what the Nest does, but about a hundred bucks cheaper? Then the Honeywell RTH8580WF might be a good choice for you.

First I’ll mention that when compared to the Nest the RTH8580WF looks boring, but that’s only in comparison to the Nest. When not in comparison it looks quite slick. The screen is large, bright, and has an easy to use touchscreen interface. Long gone are the days of “just buying a thermostat” now they offer so many features that it can be hard to sort through everything. The Honeywell RTH8580WF is packed full of useful features and the most important one is possibly the WiFi. I bet if you’re reading this then it’s because you’re in the market for a thermostat with WiFi features. The RTH8580WF’s WiFi works flawlessly. It is a breeze to connect to your wireless network and the simple instructions explain how to do this. Once connected to a network you can use a free iPhone or Android app to control your thermostat. The apps are really nice and how they operate makes sense. Recently Honeywell added the ability to also control your temperature setting scheduling (lacking in a previous build). With the ability to control the scheduling you will have complete control over your thermostat from anywhere.

The Honeywell RTH8580WF 7-Day programmable Thermostat also has a feature called Smart Response Technology. This is a feature similar to the Nest’s  in that it can learn better when to heat and cool your home. Like with the Nest, this is hit and miss. Overall in my personal experience it worked like it should. There were a couple times that it made a decision it really shouldn’t have, but for the most part the experience was pleasant. Being in a bedroom and having the ability to turn your furnace up without having to get out of bed is a great thing. I typically keep my house cooler than most and this thermostat can learn that and adjust based on my scheduling.

When it comes down to it the Honeywell RTH8580WF 7-Day programmable Thermostat is perfect choice if you’re in the market for a WiFi thermostat or even a “smart” thermostat. The Nest is much nicer and with more features, but it also costs more. Maybe you want WiFi and the smart aspect, but can do without all the extra aesthetics, if so, then the Honeywell RTH8580WF is a brilliant choice and gets two thumbs up.

Note: Before installing make sure you have a 24V “C” wire. It will make installation a breeze.

>>> Click here for more detail price reviews and ratings about Honeywell RTH8580WF… <<<

86.4

Installation

87/10

Ease of Use

85/10

Options

75/10

Screen

90/10

Price

95/10

THERMOSTAT FEATURES/SPECS

Display	Large touch screen with bright screen
Program Features	7-day programmable options
Dimensions>	6.2 x 1.2 x 4.1 inches, 12 ounces
Colors	White
Batteries>	Batteries required
WiFi	No wireless control

Pros:

• – Easy to use, easy to install
• – Screen looks great
• – Very good budget thermostat priced right
• – Excellent customer service
• – One of the best budget energy efficient thermostats

Cons:

• – Light on features, but gets the job done
• – Doesn’t work with most heat pumps and auxiliary

The brand name Lux has been associated with clocks since the company’s beginnings in 1914, when founder Paul Lux worked as a clock maker. With such a timely heritage, it’s not surprising that many Lux products today feature accurate time keeping, digital time displays and timer options. The Lux TX9000TS Touchscreen 7-Day Programmable Thermostat is no exception.

Touch-Screen Display With a Minor Issue

The Lux thermostat features a large, pale blue, luminescent display that not only shows the current temperature, but the current day and time as well.

A snowflake or flame icon tells you whether the system is in heating or cooling mode. The thermostat can be programmed to set your home’s temperature settings for the entire week, with up to four variable settings per day.

Lux boasts a user-friendly, touch-screen programming interface for its TX9000TS model. Some customer reviews takes issue with that claim, citing the interface as counterintuitive, using “yes,” rather than “enter” to switch screens, for example. Others lauded the ease of programming the system, saying they had it up and running in minutes, without consulting the manual.

(Click here to download the users manual for the TX9000TS)

Good Pre-Programmed Settings

Either way, you don’t have to program the unit to enjoy the Lux thermostat. The model comes pre-programmed with an energy-saving setup. Installing the thermostat itself just takes a screwdriver, a drill and a pair of batteries.

Simply install the thermostat to the wall, select “heat” or “cool,” and press the “reset” button to access the built-in programs.

The Lux thermostat does not automatically switch between heating and cooling. That’s an intentional feature. An environment does not need to be constantly heated or cooled to stay at a desired temperature.

The Lux model can easily be programmed to heat to a desired temperature in the morning, shut off, then cool to another temperature in the afternoon, saving energy and saving your money. It’s the reason that the Lux thermostat earned the Environmental Protection Agency’s Energy Star label, and it’s the reason that the Lux thermostat can save you up to 33 percent on your energy bills.

> Click here to find more details price review and rating of Lux TX9000TS…<<<

One of the most important tools in your home is your heating and cooling system. Responsible for keeping us at a comfortable temperature throughout any weather or temperature shifts, we would be completely and totally lost without the ability to control our inner home environments. And while there are a number of different tools and technologies on the marketplace today that we can use to set our specific climate controls and determine exactly what our seating and cooling system does, one of the absolute best has to be the Honeywell touchscreen programmable thermostat. Featuring one of the largest displays in the industry, as well as the most clean and clutter free user interface you’ll find, this is truly the best of the best when it comes to programmable thermostat systems.

The first thing you’re going to notice right off the bat is the large crystal-clear display screen that gives you all of the information you need to understand just what’s going on in your home with a glance. You can forget forever about fumbling around with different dials, trying to squint hard enough to see exactly what your temperature setting currently is at and what the and the room temperature is, as well as which specific heating or cooling systems are running. Now you’ll be able to have instant access to all of your controls with the most eye-catching back-lit display in the business.

The specs of ‘Honeywell TH8320U1008 7day 3/h 2/c Vision PRO 8000 Touchscreen Programmable Thermostat’ are:

• Manufacturer: Honeywell
• Product Dimensions: 7.5×5.5×2.3 inches
• Shipping Weight: 1.1 pounds

 

>>For more details price reviews ratings etc of Honeywell VisionPro 8000  click here

And while the large display is truly the most stunning feature of the Honeywell touchscreen programmable thermostat, it’s the programmable part of the title that really demonstrates why this product is such a game changer. You’ll be able to schedule your heating and cooling systems over multiple days, literally allowing you the flexibility you need to establish exactly how your home will be heated and cooled at predetermined times for days and days in advance. This means you can set up your thermostat once a week, have it run to perfection according to your specific schedule, and never have to concern yourself with this problem again.

This is not to say that everything is hunky-dory with the Honeywell touchscreen programmable thermostat, as it can be quite confusing at first. But right after reading through all the instructions and actually tried it myself, all of the frustration flies right out of a window!

As far as thermostat controls go, there is literally nothing else on the market as good as this Honeywell touchscreen programmable thermostat, and it’s the perfect tool to control every single part of your home.

The Honeywell TH8110U1003 is incredibly convenient setting up. One fast reference to the manual is almost all you require to getting started programming this unit, as the user interface is very user-friendly and perfectly laid out right infront of you eyes.

It’s possible to program each and every day one at a time, multi-select days and review the programming without editing it.

A portion of the features the thermostat has are not active from the box and requires you to manually turn them on once you boot it up. (Note: A couple of customers/users have pointed out that they find this part a little bit annoying.)

Program It to Simply Save Money

The unit will enable one to have more control than in the past and allows you to keep the home at a comfortable level all of the time.

The changeover element is yet another smart feature of this Honeywell thermostat. It simply warms the home in the morning and cools it down during the day so that you will have the perfect temperature when you get home from work and at the same time you are saving money on your energy bill.

Another feature found handy on the Honeywell TH8110U1003 is a circulation feature on the fan. It will run the fan 35% of the time to maintain the air in the house.

If you may be planning about buying a new thermostat then you should really considering getting this one, you are surely going to be very pleased once you have it up and running.

As far as heating and cooling components of your home go, there is literally nothing more important to your entire system than the thermostat control module that you decide to leverage. While there is a lot of talk in the industry regarding power saving and energy-efficient heating and cooling units, the pros and cons of central air, and even which manufacturer is the most reliable and trusted in the business, none of that amounts to a hill of beans if you don’t have a reliable and effective control system to run the whole show. Luckily, the Ecobee smart thermostat full-color touchscreen unit is just that kind of control system, one of the most stunning both visually and control wise thermostats on the market today.

While it is a bit larger than most thermostats you’re used to using or seeing in homes, especially if you’re using those old turnout solutions that have been so popular in house building for the last hundred years or so, the Ecobee smart thermostat full-color touchscreen is absolutely the next generation of thermostat control systems. While this is certainly not the first or only touchscreen unit on the market today, it is one of the few reliable full-color screens at this price point, making it one of the smartest tools you could invest in. There are other backlit solutions that look nothing like this, which is closer to a cell phone or tablet interface than anything else.

The specs of ‘ecobee EB-STAT-02 Smart Thermostat 4 Heat-2 Cool with Full Color Touch Screen’ are:

• Manufacturer: e-concept Distribution France
• Product Dimensions: 10.8×6.1×3.4 inches
• Shipping Weight: 1.7 pounds

>>Click here to find more details price reviews and ratings of Ecobee Smart Touch Screen Thermostat…

With built-in WiFi  you’ll be able to instantly connect to any of your devices through the Internet, helping you to moderate and control your home’s heating and cooling system even when you’re not in the building. This brings us to the simple fact being that you’ll be able to use your new Ecobee smart thermostat full-color touchscreen in with your favorite Google Android or Apple iPhone smart phone or tablet solution and enjoy incredible and versatile control. This takes home heating and cooling to a whole new level, and when you combine that with the simple fact that your thermostat can also search for and update its weather conditions for your local area and determine the ideal energy and temperature control settings, you have a thermostat Ecobee smart thermostat full-color touchscreen solution that almost runs the show all on its own.

Verdict of Ecobee EB-STAT-02

While some people have complained that it can take a little bit of getting used to, especially if you’re not particularly well-versed with the tablet or smart phone technology of today, it shouldn’t be a problem for most people. Hands down one of the most attractive and best Wi-Fi enabled thermostat controls on the market today, you’d have to be a little crazy not to invest your money with this solution. Amazon offers incredible discount on this particular model often, be sure to click on the link below to check it out!

Pros: This thermostat is very user friendly; I found it especially easy to operate as it seems to present the user interface similarly to many smart products. The installation process was much simpler than I thought it would be, but detailed directions made the step by step process easy to follow. It looks great in the modern, technology rich home. Its attractive, yet subtle appearance add a degree of sleekness and modernity to any house. The Ecobee3 Wi-Fi Thermostat provides the user the ability to control sensors and temperatures around the entire house from the convenience of a smart phone app. Being able to have several sensors located around strategically around the home add to the level of accuracy for the thermostat within the home. This improved level of accuracy leads to lower energy bills, fewer hot or cold spots around the home, and an overall more functional space. All of these facts help to increase the potential resale value for the home owner. The sleek design features of each aspect of the Ecobee3 package make this package that much more appealing.

Cons: The level of customer service provided by the manufacturing company could be much higher. Wait times and response times should be much quicker than what is currently provided. In addition, the tech support that is offered online also leaves something to be desired. When attempting to contact the manufacturer or the tech support that they offer, wait times are too long and hold times are not reasonable. As this is an accessory for the home, the Ecobee3 Wi-Fi Thermostat does not always tie into an existing system without any issue. This device is also a piece of technology, so it is not always completely reliable. Just like any technological tool, the Ecobee3 can suffer some glitches which require interactions with tech support.

Feature wise, the Ecobee3 Wi-Fi Thermostat stands apart from the competition, because it is so user friendly. Aside from the lack of support from a technical standpoint, the product is attractive, simple to install, and convenient to use. Although this is a relatively new item, it is apparent that it will continue to be a largely sold one.

In conclusion, this package is best suited for the home owner who is looking to improve the quality of air and temperature in their home in an aesthetically pleasing way. For the price, the Ecobee3 Wi-Fi Thermostat is an excellent investment and one that comes highly recommended. This thermostat is unique in the fact that it is incredibly easy to install for any customer even if they do not have a great deal of experience. The ability to control the temperature from an easily installed smart phone app. only adds to the appeal of this exciting home improvement option. The subtle design only adds to the decor of any room in the house. Whether or not to add the Ecobee3 Wi-Fi Thermostat to any house should be a very simple decision to make. Commit to the change and appreciate the ease with which your home’s temperature is precisely controlled more every day!

>>Click here to find more details price reviews and ratings of Ecobee3 wifi Smart Thermostat…

WHAT IS A SET BACK THERMOSTAT ?

A set back thermostat is basic type of non programmable thermostat that does not have programming feature. Instead the temperature set point can be altered only through manual operation. Traditionally they were mechanically operating only but now most modern thermostat come with electronic control.

These thermostats are inexpensive alternative to contemporary programmable or smart thermostats.

It is also suitable for people who have irregular schedule so require quite a lot of manual intervention.

WHAT DOES SET BACK MEAN ?

Set back in temperature is the change in set point of temperature to allow the heating or cooling device to res or in other words run at lower load or not run at all.Basically the furnace or your ac etc will run only when the temperature falls below or rises above your setback temperature.

This will allow the system to use less energy and results in savings.

SET BACK TYPES

Basically there are two types of setbacks-

When the home is vacant-In this type you lower the load of your hvac equipment when no one is at home and so will not feel uncomfortable.

When sleeping at night-At night you can lower the heating or cooling as night temperatures are lower than day so you don’t need that much heating or cooling.This is called night-setback.

DOES SET BACK THERMOSTAT SAVE ENERGY BILLS?

 

There are debates around whether setback result in saving or not.

Well according to physics it should. Any degree of setback no matter how small it is will save you money.

The amount you can save will depend on your commitment to save and also how well insulated your home is as well as the type of system you are using. A slow acting system will result in less saving while a well insulated home will also save more money.

RELATION BETWEEN SETBACK TIME DURATION AND SAVING

Well US department of energy says that 1 degree of setback for 8 hours results can result in 1 % of energy saving.Well this may vary according to your system and insulation of home.The most important factor is your commitment to save energy and thus have regular setbacks for the long run whenever you are not at home or asleep at night.

Here is a simple chart of setback temperature and proposed energy savings.

 

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TIME	6AM TO 9PM	9PM TO 6AM	PROPOSED SAVING
Winter	68°F (20°C)	58(14°C)	11 % (6°C/8hrs *15 hrs)
Summer	78°F (26°C)	96(36°C)	18 % (10°C/8hrs *15 hrs)

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SWITCH BACK TO NORMAL TIME

Well you should also look into the time it requires for your system to bring the house back to your comfortable temperature and thus adjust you normal time in advance. You don’t need to bother with this in Smart thermostat with smart recovery feature like in Honeywell but with non programmable set back thermostat you need to keep that into account.

SETBACK AND HUMIDITY

 

How much you should set back the temperature not only depends on the outside temperature but also on the humidity levels. You should find a best set point so that Relative humidity of house is in comfortable range.

In winter the RH may increases at night causing condensation at windows walls etc.

In summer too If your Ac doesn’t run less than required there may be rise in humidity causing moisture issues like molds etc in the house.

SET BACK WITH HEAT PUMPS

 

If you have heat pump you can save energy efficiently only in cooling mode when using setback. In heating mode a heat pump uses back up electric resistance heat system to heat back to normal temperature and set back will cause the heat pump it to operate inefficiently. A moderate setbacks will give you optimum saving. Few companies make thermostats with algorithms to minimize use of backup electric heat system. With such thermostat you can have much more setbacks and thus savings.

BEST SET BACK OR NON PROGRAMMABLE THERMOSTATS

If you are looking for a non programmable thermostat chances are you have an old traditional furnace or cooling system or you have a irregular schedule so you don’t want to rely on programmable or smart thermostats.

There are basically three type of thermostats

Low voltage

Line voltage-120 to 240 V

Millivolt system.

When looking for non programmable thermostats check if its compatible with your system. In following we have listed more thermostats compatible with most of the systems or listed separately that are just for single system like Line voltage thermostats.

Honeywell RTH111B1016/E1 Digital Non-Programmable Thermostat

This is the cheapest low voltage thermostat you can get. Know that it is snot compatible with electric baseboard heating as it do not support 120 or 240 line voltage. It has excellent feedback on amazon. Some of its features customers liked are its easy set and precise temperature control. It keeps the set point on power outage as it operates on 2 AA batteries too. Overall its a best value for your money if you don’t require anything fancy or cumbersome.

Click here for more info,ratings,price and reviews of Honeywell RTH111B1016/E1 on amazon.

HONEYWELL TH3110D1008 PRO NON-PROGRAMMABLE DIGITAL THERMOSTAT

Being under a warmer shelter when it is cool like the Artic would be the best and the most soothing feeling of all. And to have such comfort, a Honeywell non-programmable thermostat is the best choice. This is a non-programmable device so even if your grandpa has to use it, he can do the task easily. This is a simple yet effective device and the best for those you do not require the ultra-modern features of scheduling and programming for days.

Click here for more info,ratings,price and reviews of HONEYWELL TH3110D1008 on amazon.

 

The display of this device having a backlit digitization. This means that the display of this Honeywell thermostat makes the information on the screen highly readable and thus makes it easy for you to use. Even under different lighting conditions, the display of the unit makes itself accessible in terms of reading. It even displays the current as well as adjusted or regulated temperature on the screen at the same time. Moreover, the temperature control and adjustment through this unit are very simple and precise.

EMERSON NP100 NON-PROGRAMMABLE THERMOSTAT

Emerson is a leading brand in the industry of air conditioning, ventilation and heating and cooling solutions. It has a wide span of service that covers the industrial, residential as well as commercial sectors as well. Hence this very company has an immense experience and skills of manufacturing a thermostat.

The NP100 thermostat by Emerson is a non-programmable unit that supports only the single stage heating or cooling systems. However, if you are having single stage systems then this device proves out to be the best unit is the segment of non-programmable gadgets. The brand has taken care of the quality and sustainability so that the users have no issues with the component and can enjoy the service. This thermostat has an easy to see and read display with a backlit property so that you can easily get the information that is being displayed on the screen.

And regarding the temperature adjustments of the device, it can make precise alterations in the temperature up to the range of plus/minus 1. Now, this is very effective when you and your family member have a different comfort temperature. Hence you can adjust the thermostat at an optimum temperature so that all of you can get the desired atmosphere.

Click here for more info,ratings,price and reviews of EMERSON NP100 NON-PROGRAMMABLE THERMOSTATon amazon.

Emerson 1F83C-11NP Conventional (1H/1C) Non-Programmable Thermostat

Emerson company provides automation and engineering services for wide range of industrial and home applications. It also manufactures some of the best smart thermostats. While above thermostat is a non programmable design of Emerson it has some advance feature like screen lockout to prevent unauthorized access and also temperature limits within which your HVAC equipment will perform. A large display and easy set up and precise control are also its recognizable features. It is also compatible with multiple type of system including of up to 1 heating and cooling stages, heat pumps and millivolt system with 3 wire zone valves.

Click here for more info,ratings,price and reviews of Emerson 1F83C-11NP on amazon.

EMERSON 1E78-140 NON-PROGRAMMABLE THERMOSTAT

Another Emerson thermostat that has secured a position among the best non-programmable thermostat top list. However, this unit has a specific usage only. This device supports only heating system devices. Thus any single stage heating device can be controlled and managed using this thermostat. Moreover, on the better side, it is very affordable and best for a single purpose use. So you have a device that can manage individually all your single stage heating systems. Not to forget that, though the unit has a very limited usage it has a very efficient work performance which cannot be neglected for the good.

The design of this unit is quite simple and so is its working. So, when it regards to the working of the device, it has simple operations and functions which make it accessible for all, the aged ones as well as children. And the construction of the unit is also very basic. It has a display screen that has a backlit display, so the readability is the best and it has only two click buttons which can operate the temperature swing. Thus it is the best non-programmable thermostat without complex operational tasks and with the effective working for the best atmosphere inside the house. It is an efficient thermostat from an efficient company.

Click here for more info,ratings,price and reviews of EMERSON 1E78-140 NON-PROGRAMMABLE THERMOSTAT on amazon.

Lux Products DMH110 Non-Programmable Digital Thermostat

This is a basic model of lux which manufacturers adjustable differential thermostats. This thermostat is also a adjusting differential type thermostat with +- 3 differentials.It is compatible with sigle stage Gas, Oil, Electric or sigle stage heat pumps and also millivolt systems.Easy installation and temperature is switchable to Celcius and Fahrenheit. If you have a short cycling problem and want a handy inexpensive thermostat this one is definitely for you.The setback is achieved by save button which allows to alter setpoints.

By doing so the thermostat automatically changes the temperature of the device to a better and energy efficient temperature. Now, this can be really helpful in cutting down your bills and saving some money for you. Moreover, the unit can be changed to Fahrenheit when required and to Celcius as per the requirement. This is called the comfort of power.

The accuracy of this product is sensational being a non-programmable thermostat device. The battery power of the same is also very long lasting and powerful. Hence doing the value addition for the unit there are various features that are at the best. And it is great that you can get at such a reasonable price. Furthermore, it has a large display that offers clear information. Thus the temperature of the unit can be read properly. This allows you to make the required changes as well.

Click here for more info, ratings, price and reviews of Lux DMH110 on amazon.

PRO1 IAQ T771 Heat or Cool Only Electronic Thermostat

Pro1 also makes adjustable differential thermostats. The temperature differential on this thermostat is from 0.2 to 2 degree F. The power supply can be battery or line voltage. Most people find it to be excellent replacement for their garage or RV owner and want to run in low temp but prevent temperature going below freezing. When working you can turn it up again to comfortable temperature. They find it to be better than Honeywell which has a lower set point of 35 degree F while this has lower set point of 25 degree F.

Click here for more info, ratings, price and reviews of PRO1 IAQ T771 on amazon.

Line voltage

Honeywell RLV3120A1005/E1 Digital Non-Programmable Thermostat

This thermostat is designed for electric baseboard heating only. It is a line voltage thermostat with both 120 and 240 V line compatibility. No batteries are required and set point is retained in memory. Compact design allows easy installation. You can display temperature in Celsius and Fahrenheit. The temperature control is accurate (0.15 degree) and a on screen heating power indicator. It is also cheap when compared to other baseboard heater thermostats of Honeywell or other companies.

Click here for more info, ratings, price and reviews of Honeywell RLV3120A1005/E1 on amazon.

Honeywell Manual 4 Wire Premium Baseboard/Line Volt Thermostat

This is another baseboard type thermostat with mechanical control. Both 120 and 240 V compatible and very easy to install. It can control up to to 5,2800W with 2 or 4 wire non polarized connections. This works on most basic type bimetallic temperature sensor that actively senses temperature and can be bought for just 17 bucks on amazon and has impressive ratings and feedback.

Click here for more info, ratings, price and reviews Honeywell Manual 4 Wire on amazon.

In modern days where automation has reached the residential and is no longer the norm of only industries and factories there are certain terms or technical jargon that people still struggle with.

Basically automation is  part of a subject called control systems. The idea is that you have a control parameter(in our case temperature) and and the set point we want the temperature to be. The work of thermostat is to check the difference between the measured temperature and set point and control the fan or your heating and cooling system to adjust the temperature.

The thermostat is analogous to P+I (in parallel) controller used in commercial temperature controllers. P stands for proportionate I stands for integrate. P part of controller increases output directly proportionate to the difference between set point and actual temperature, while I affect the rate of change of its output proportional to its input by taking into account time duration of error signal(Set point – Actual temperature) to adjust the next switch on and off time accordingly and basically prevent offset error(final range of temperature swing in stable condition). Offset error is high if only P control is used.

In other words more accurate temperature control. This is done electronically by adjusting the cycle rate(ON+Off times ) of HVAC system proportionate to sum of output of  P and I controller.

 

The PI controller is subset of more sophisticated PID controller where D stands for derivative. P alone produce large offset or steady state error. It also increases maximum overshoot of system. So I part which produces output rate of change proportional to error is used which reduces this steady state error and bring the system to exact set point but I alone of controller can make system unstable and slow (Toggling for longer time.)

So a derivative function is added to make it stable and improve the transient response(reduce overshoot and undershoot and response time). It is anticipatory meaning it anticipates error and is used to limit over and under shooting of parameter. The main disadvantage is that it never reduce steady state error and produce saturation effect and amplify noise signals. Also since house thermostat are ON/OFF, rather than continuous type controllers D is generally not required.

Dead Band or Noise margin.

It is a differential is also called hysteresis which is included in control system to account for noise or small temperature swing.

The above loop is shows there is +T and -T margin for temperature to swing beyond or below which the output changes. This is done to account for noise and other factors not in control that may unwantedly change sensed temperature of thermostat. The work of thermostat is to adjust cph to keep temperature in this range of temperature near set point. Higher differential will result in less cph and vice versa.

That is why you may not notice HVAC instruments switching on or off in decimal temperature changes because your thermostat is +-1,2 or 3 differential temperature rated.

The noise may look like below(Graphical representation)

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As you can see using margin for noise etc leads to less unwanted toggling(On/Off) of HVAC instruments.

Why does your thermostat over cycle or cycles frequently.

First understand what is cycling. Cycling is a process of thermostat(temperature controller) to keep the HVAC instrument(ex-AC in summer, Furnace in winter) on and then off for a period of time so as to maximize efficiency. One such period is one cycle.

Why Frequent cycling should be avoided. Frequent switching is damaging to furnace or AC(specially compressor of AC) components due to constant wear and tear in the process. Also it may cost you money because a furnace or AC is more efficient if it is running continuously. It requires some time to build up that efficiency. So if it is switching on/off most of the time it is running predominantly on low efficiency.

Frequent cycling may be because of two reasons.

1.)Your thermostat is sensing some noise signal, like from an air coming through the hole behind the thermostat or air vents, windows, doors etc. To remove that make sure the hole behind the thermostat is properly sealed and no air draft is affecting the thermostat.

2.)Second is because of your boiler or ac system not responding as quickly as desired. So taking into account the “time  error” the I part of thermostat controller increase output which in turn increases cycle rate to keep temperature at required set point. Another reason may be that your boiler or Ac is over efficient and delivers heat or cooling faster than required resulting in frequent over shooting  as can seen in above diagram. To tackle this you must install a proper sized furnace or AC in the first place after consulting your HVAC person.

If no such option are left you can opt for an adjustable cycle rate differential thermostat.

1.)Honeywell thermostat cycle rate adjustment9

Honeywell thermostats do not come with adjustable temperature differential. It is fixed to +- 1 degree F but with some of the models you can adjust the number of cycles for heating(Winter) or cooling(Summer). After you change the cph(cycles per hour) it may take few hours to adjust because the thermostat has to learn the heating or cooling times so that the temperature is as close to set point as possible.

If you refer to Honeywell thermostat manual it states how you can change the cycles per hour rate using program buttons. It also tells how many cph is recommended for various type of system. Here is a  picture of what to find it in the manual.

Some Honeywell thermostat that have adjustable cycle per hour are

HONEYWELL RTH8500D (Heating only) and HONEYWELL RTH230B

You can check manual of the model here before buying – honeywellmanual.com

2.)Lux thermostat-

If you looking for a cheap thermostat because you want to control your hvac short cycling issue. All lux thermostat have a differential setting upto +-3 with increments of 0.25 degree F. In these type of thermostat if you system is short cycling just increase the differential temperature and you would be ok.

One Good model of Lux Thermostat Program 7 day with selectable smart recovery, universal compatibility.

3.)Robertshaw thermostat-

Robertshaw offer many programmable and non programmable thermostat. All comes with differential setting of 0.5 to 3 degree F for first stage of system. There is also a second stage differential. When first stage cannot keep the desired set point for more than set timer(20 minutes default)  and the temperature difference is more than sum of  first and second stage differential the second stage system gets on to lower the load on first stage.

Two good models of Robertshaw programmable thermostat are

Robertshaw RS5220 Programmable Thermostat 2 Heat/2 Cool

Robertshaw RS6110 1 Heat/1 Cool Digital 7 Day Programmable Thermostat

4.) Venstar thermostat

Venstart designs beautiful color screen wifi thermostats. But main feature is that it allows differential temperature of upto 0-6 degree F. Also if the thermostat is designed for two or more stage heating/cooling the it allows differential temperature changes for second stage as well. A timer or time lag is introduced between activation of first and second stage systems and similarly for higher stages. The differential setting is is referenced as dead band in its manuals.

A good Venstar thermostat is Venstar T1800 7-day Programmable Digital Thermostat

It has dead band of 1-6 degree for first stage and 0-10 for second and third stage with adjustable timer between stages.

5.)Ecobee smart thermostat-

If you want to go for smart thermostat though i don’t really recommend unless you need it for other than the frequent cycle differential settings. Ecobee is the only thermostat that offers differential spread of 1-3 degree F. All other factors considered it is excellent investment in terms of ts smart features and operation like geofencing and auto adjust using humidity and temperature sensor that you can place any where across the room.

Check out ecobee3 lite Smart Thermostat, 2nd Gen on amazon.

6.)Emerson Thermostat

Emerson offers two thermostat with adjustable cycle rate

a.)Sensi-

Emerson thermostat do not comes with differential spread but offer to change cycle rate as slow , medium  or fast from the app.

Slow is suited for hot water boiler steam heating

Medium for Ducted heating/cooling

and for most accurate control choose fast.

Check out Emerson 1F85U-22PR Programmable Thermostat on amazon.

b.)White rogers-

White rogers also has a two option SL anf FA for slow and fast cycles per hour for heating only.If after changing the cph to FA or SL optimum cph is not achieved contact local service person. Cooling cycle rate is not adjustable and is fixed.

Check out White-Rodgers 1F80-361 thermostat on amazon.

Recommended CPH for various furnaces in well insulated new homes with low heat loss.

1.)Heat pumps-1.5 to 2 cph

2.)Electric furnace-3-5 cph

3.)Gas furnace-3-4 cph

4.)Oil furnace-3 cph

Are you a rental property or mini business owner, or do you have curious small children in your home.In such case you certainly want to lock your thermostat to control who can or cannot access the temperature setting to prevent damage in terms of energy bills or hvac instruments. Well you can be relieved because if you want to buy a wifi thermostat most famous brand and their models offer such functionality, even the china made models like Beok etc. We list some of the best wifi thermostat with lock out based on their ease of use, applicability and trouble shooting.

1.)Emerson sensi wifi thermostat .

Buy any model of Emerson sensi. It comes with lock feature from app or from the keypad if it is not touch screen. We like the classic Emerson sensi without touch screen or its use of ease for lock out.

The keypad can be locked remotely or at the device by pressing menu and up button for 5 seconds But it cannot be unlocked from keypads.For that you have to use the app as shown above.This is ideal if you do not want other occupants of the home or building to change the setting except you who will have full control from the app.Perfect for landlords and rental property owners.

To assure that you have  keypad lock you need to have to confirm that you have

Firmware version: 9.06 or greater

iOS App version: 1.1.0 or greater

Android version: 1.091 or greater

In addition Emerson updates the firmware within 24 hours of installation son you don’t need to upgrade the thermostat.

Click here for more details,price ratings and reviews of Emerson sensi on Amazon

2.)Honeywell Thermostat-All wifi honeywell thermostat comes with a partial or full lock mode. This allows you to completely or partially lock various features of thermostat. Fully full lock prevents accidental or unauthorized change in heat/cool temperature set point.

While locking honeywell gives you a pin which you can reenter to unlock thus you should remember the pin even if you forget the only option which remains is to call customer support. Toll free no-18004681502

Things which you should have before calling customer support –

1.model number

2.date code

which you can easily find in menu>equipment status

The best and economic model we could find is Honeywell TH9320WF5003 Wi-Fi 9000 because with these wifi models unless users has the pin you will be assured that no one can change your settings but in keypad lock thermostats the lock and unlock is just few button press away on the thermostat.

You can also set minimum and maximum temperature range and give partial access to your tenants so that they can only change temperature set points within your allowed range. To do that go to

Menu>Preferences>Advanced preferences>programmable>Set minimum and maximum temperature>Done>Previous menu>Home.

Thermostat with keypad lockout is not particularly suitable for landlords or rental property owners as the guest are totally locked out. Even if you give partial access it wont be secure and cause huge money bills if tenants mess up with temperature setting continuously. So thermostats which allows to set temperature limits is recommended.

For other who want a personal thermostat for home and just don’t want children or unauthorized person accessing the thermostat use keypad lock out models.

NOTE-Honeywell round lyric-2nd generation doesn’t have a lock out feature complete model list  model list go out here

If you want  keypad lockout try these models:
TH8110R1008, TH8320R1003, TH8321R1001, TH8321WF1001, TH6320WF2003, TH6220WF2006, TH6320U2008, TH6220U2000, TH6210U2001, THX9421R5021.

For range stop settings, to set high and low temperature limits for heating and cooling try-
TH8110R1008, TH8320R1003, TH8321R1001, TH8321WF1001, TH6320WF2003, TH6220WF2006, TH6320U2008, TH6220U2000, TH6210U2001, THX9421R5021, TH6110D, TH6220D, TH6320U1000, TH5110D, TH5220D, TH5320U.

Click here for more details,price ratings and reviews of Honeywell TH9320WF5003 Wi-Fi 9000 on Amazon.

3.)Ecobee wifi thermostat-Like all above companies Ecobee also give locking option for all its models. While being  expensive it is a smart solution for landlords because it allows to set temperature range limits for both heating and cooling.  To do that

1. Go to Menu > Settings > Preferences
2. Tap onHeating range/Cooling range
3. Set the upper and lower limit values.
4. Tap on Save.

Tenants can choose between heating and cooling but without requiring the pin and also not changing the temperature limits.If you want to be extra sure you can download an app called iftt which gives you the alert when the temperature program changes.

To lock an ecobee go to menu>settings> access control>enable security code and enter 4 digit password that you want to set. Then select  features that you want to require password or simply select all to lock the thermostat completely. If you forget your access code here are the steps to recover it

1. Login to ecobee.com   and you can disable the password from there by going to Settings then access control and select disable.

or

2.)Call support and after confirming your identity they will send you the access code via email or through sms.

Click here for more details,price,ratings and reviews of Ecobee3 lite second generation on Amazon.

4.)Nest smart thermostat.

Locking a nest thermostat is very easy. It can be done with the app or from the thermostat itself. One thing to point out is that nest doesn’t allow to set temperature ranges for heating and cooling separately. You can just adjust the temperature lower and upper limit. This is also a bit complex.

Nest allows you to lock in in two configuration.

a.)Heat or cool mode-In this mode you can lock in either Heat or cool mode. After you create a four digit pin you can set temperature limit for either heat or cool mode. Guest can change the temp by moving the nest outer ring within your set temperature but cannot alter the heating or cooling mode without the PIN. Also when You lock your thermostat with app  the smallest temp range you can set is 5 degree(Eg 70-75).There is no such limit when you lock at thermostat itself and you can set the temperature to a fix value.

b.)Heat-cool mode-When you lock your nest in this mode either by app or thermostat you can also set temperature range limit.The lowest range is 2 degree.eg(70-72).Also no one can change temperature by turning the ring without knowing the pin.Only you can change the set point using phone app.

So in effect you can only lock your thermostat for guests or tenants for a particular season and then you have change it or you have to give them app access in case of heat-cool mode as the ring slider wont work.

How to lock nest.

1.Tap setting icon located on top right corner.

2.)Turn the outer ring till Lock  option show up on the screen and tap on it

3.Enter 4 digit pass code twice.

4.)If you want to lock in heat-cool mode you have to do an extra step in the thermostat(not app) to set the temperature range.

5.)After you create passwords You can set temperature range for heat or cool mode or for heat-cool mode from app.

Note-If you forget the pin you can reset it via app and receive password reset link.

You can also do it via app.Here are the steps.

1.)Select on settings.

2.)Scroll to the bottom to lock.

3.)Tap and select the 4 digit pin twice.

4.)If you locking n Heat or cool mode you have to set the temperature range by dragging slider to min amd max range Remember the minimum allowed range in app is 5 while with thermostat there is no such limit.

Click here for more details,price,ratings and reviews of nest third generation thermostat on Amazon.

As you know probably that wifi thermostat are not cheap.They easily cross the 100 $ range.But in an age when everything is becoming smart device controlled like Alexa or Google assistant one would naturally gravitate towards a wifi thermostat that could be used with such devices in your home.

However finding a affordable wifi  thermostat could be a pain when looking at so many models.So we have compiled a list of some good and cheap wifi thermostat that you could get from amazon.Based on customer reviews and experience using them the thermostats listed below are a decent value for your money.

One thing we would like to point out is that most of the time you don’t require a smart learning thermostat like Nest.This is because of the complexities of using such features.Your wifi thermostat may or may not have smart features like Geofencing.IFTT,Auto adjustment of schedule based on your past setting and other conditions like wether hmidity etc. But these are hardly the features most of the people will use.For example Geofencing which lets you change temperature with geolocation is hardly of any use if you routine is same on most of the days of the week.So a simple 5-2 days schedule will solve the same purpose.Also adjusting temperature multiple time whether automatically like in smart thermostat or manually is damaging to you hvac instruments and may cause higher energy consumption.So predominantly a thermostat which you can program and control remotely through app or your voice is the most desired features that will be more than you want to use in wifi thermostats.The prices of these thermostat will reflect according to these feature on the thermostats.

1.)Vine WiFi Programmable Smart Home Thermostat – 2nd Gen

Vine thermostat can be bought for about 70 dollars and it has all the feature of a wifi controlled thermostat.However it does not have few of the features like Geofencing and auto schedule feature.You have to manually program the thermostat for different setting you want.Other than that this device can be connected to any of you smart devices like tablet phone or home automation devices and can be accessed remotely.

It is compatible with most of the HVAC devices common in US and Canada and comes with weather forecasting up to five days through its cloud compatibility.It also has humidity indicator.Amazon offers tech support or the product for upto 90 days and it also comes up with 30 days return no question asked and get repair service for 3 years and a lifetime technical support.Vine also claims to give feedback within two working days.

Click here for more detail, price , reviews and ratings of Vine WiFi  Thermostat 

2.)Bosch Connected BCC50 Wi-Fi Thermostat

The Bosch thermostat is also compatible with most of the hvac devices and requires C wire and can be bought for 80 bucks.Also like all wifi thermostat can be controlled though phone tablet or smart devices like Google Home or Alexa.It reads humidity as well as temperature o the room.Although it has mixed and polarizing reviews it is still a good value for money as most find it easy to set up and app easy to use.You can set up to 4 preset schedules or program it as your requirement.Here the set up video by Bosch.

However like above it does not have auto adjust or IFTT feature or Geofencing.In other words it is not a learning thermostat.

Click here for more detail, price , reviews and ratings of Bosch Wi-Fi Thermostat

3.)Radio Thermostat CT50 7-Day Programmable Thermostat

This 7 day programmable thermostat works with most of the HVAC units whether single or multi stages.It is the cheapest thermostat in the list and can be bought for about 55 $.It can be powered by using  either 3 AA batteries or a C wire.The good feature we like is that you have the option of Geofencing with this thermostat along with other features which are common with others like remote access with smart phone tablet or home assistant devices.The thermostat can be accessed by multiple phone so that more than one family member can adjust temperature from anywhere as long as you have internet.It comes with pre built energy saving program that you can alter as your requirement. However it is not compatible with home automation devices.

This device may not be compatible with windows 10. This video explains how you can overcome that.

Click here for more detail, price , reviews and ratings Radio Thermostat 

4.)GoControl Z-Wave Battery-Powered Smart Thermostat

This thermostat is also compatible with most of the contemporary hvac system like standard 2-stage Heat & 2-stage Cool or on On Heat Pump Hvac Systems With 3-stage Heat & 2-stage Cool.

Has an android or ios app for controlling the temperature However it requires an Z wave hub to connect to you phone or other smart devices like Amzon alexa or Smartthings. This can be an additional cost if you dont have it yet.Other than that the thermostat is easy to use and install.Can be 4 AA battery powered (included) or 24 V C wire powered.It do not have a IFTT or Geofencing or auto adjust feature.

Click here for more detail, price , reviews and ratings of GoControl Thermostat

5.)Emerson Sensi Wi-Fi Smart Thermostat for Smart Home, DIY.

The thermostat is an old model of Emerson and can be bought for 97 $.It offers most of the feature of a smart thermostat like Geofencing,smart alerts for extreme temperature or humidity.The installation instruction is provided in the app with which you can manually install the thermostat in minimum of 30 minutes.The thermostat is also compatible with most hvac instrument.You can check compatibility from here.

Also it is compatible with most home automation like Apple home kit Amazon alexa or samsung smart kit.

Click here for more detail, price , reviews and ratings of Emerson Sensi Wifi Thermostat

6.)AirPatrol WiFi Smart Air Conditioner Controller

This thermostat is on our list because this thermostat will not require you to have any changes in your current AC system even if your AC system is old.The only exception is wired central ac system that do not use ir remote control.  It can connect to 10,000 different AC and heat pump models.If you consider the cost of buying a new Ac system because your contemporary thermostat wont connect to it this a deal in terms of money.If your AC is multi split you can add multiple thermostats and control all of them with one app on a single phone.It has Fahrenheit as well as Celsius reading option.Most customer found it easy toset up some even in 5 minutes.

Also this is a smart thermostat as it allows IFTT and geolocation(Geofencing) to control your temperature.All that for $100.

Click here for more detail, price , reviews and ratings of AirPatrol WiFi Air Conditioner Controller 

Other than the obove thermostats i found few thermostat like the Beca,Beok or Qiao xi pan on  which are chinese manufacture selling on Amazon but is available for purchase in Alibaba.These thermostat are not so reliable for obvious reason but if you want a thermostats quite low in price you can find multitude of these thermostats  at aliexpress.com and find them or similar other wifi thermostats quite easily there and get it mailed through cheap china post.But as said these thermostat wont have the customer support or maybe clear installation instruction as i read in few of the reviews for models sold on amazon.

Temperature is property of any matter which tells the sensitivity of hotness that we will feel when we touch it. How ever it does not indicate how much total heat energy it contains. For example of same mass of water and coal at same temperature water has absorbed more heat because its heat capacity is higher. But since temperature is a property which is associated with average energy each of its molecules of the substance is having you feel the same sensitivity when either coal or water at same temperature is touched with bare hands.

From Maxwell Boltzmann distribution we see that as temperature increases the the curve tends to be more flat that means average energy of molecules increases with rise in temperature.

It is different from entropy(a measure of randomness of molecules). For example if water and coal are at same temperature and have same mass and absorbs same amount of heat, coal will undergo more temperature change and lesser entropy change ie energy distribution among their molecule will be less random compared to water. That means energy distribution among its molecules will be more uniform.

Mathematically E=H/T  and H=mCT Where E =entropy H= Energy And T=Temperature(Kelvin or absolute temperature) m=mass C=Specific heat capacity.

Entropy=(a measure of randomness of molecules). For example if water and coal are at same temperature and have same mass and same amount of heat is supplied to both, coal will undergo more uniform distribution ie, energy distribution among their molecule will be less random and average motion energy change per molecule will be more compared to water. That means lesser molecules will be at rest compared to water.

So conclusively, if heat is given to a substance and its temperature does not rises and substance does not do any work then it entropy increases which means less order so the whole energy given is not distributed uniformly among its molecules most of that given energy is concentrated among few number of molecules.

Now that you know much about temperature watch this interesting video.

Negative temperature

Now we know the entropy of system may increases or may remain the same. But what if the entropy decreases or the substance become more ordered. Such a substance is said to have negative temperature even though it has absorbed positive energy. For such a system to exist it has to saturate in entropy with probability of  higher states being small as illustrated with Fermi Dirac equation,

P(Ei) =n0(e–ΔE/kT) ,k=Boltzmann constant T=Temperature Ei=i^th energy state ΔE=Difference between two energy state no= Probability at fermi(base level) at temperature T. At zero Kelvin it is 1/2.

The probability(P) equation is for quantum physics by Ludwig Boltzmann. It is similar to Maxwell Boltzamn but instead of velocity, discreet energy states(A set of numbers defined by quantum physics. It has more to specify that energy state then the actual energy of that state.) are used .

At negative temperature there is a change in state or vice versa ie, due to the change of  state the system achieves negative temperature .

Such a system is employed in lasers where the entropy is lowered but heat is applied. But if this is continued to saturate the entropy it will transit to absolute temperature of negative infinity.

Negative temperature does not mean no absolute motion of molecules or particles but a change in its state.

To achieve absolute negative temperature in labs the systems is cooled near to absolute zero as illustrated in the video below.

https://www.youtube.com/watch?v=yTeBUpR17Rw

Most familiar systems cannot achieve this temperature but if such a system comes in contact with normal system heat will flow from negative to positive temperature.

Such a system if stable is hotter regardless of its temperature than any positive temperature system and becomes a continuous heat energy source because of the change in quantum state of the system.

More here.