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Thermostat Selection Guide - This article will help you select the right type of thermostat for the HVAC system you have installed. It offers a comparison matrix for you to choose the right thermostat replacement. Get it right the first time!!!
So you have made a choice to replace the thermostat in your home or business and you decided to do it yourself. Hopefully, you will follow the advice on this website and read the instructions before replacing the thermostat.
Thermostat Selection Guide | Buying the Right Thermostat
It is recommended if you do not know what you are doing or having any doubt whatsoever then please consult a professional. One of the biggest issues with replacing your thermostat is selecting the proper thermostat. This will depend on the air conditioning and heating system which you have installed in your home. By and large, most thermostats are low voltage thermostats however, there are line voltage thermostats, Millivolt thermostats, and other proprietary solid-state thermostats that come with many mini-split or ductless systems.
Other selection factors include selecting a programmable thermostat, non-programmable thermostat, and digital or mechanical thermostat. You need to first figure what kind of air conditioning and heating equipment you have before selecting the proper thermostat. In some cases selecting the proper thermostat will require some technical knowledge concerning low voltage thermostat circuits.
Thermostat Selection Guide - Matrix Selector | Choosing a New Thermostat
| Low Voltage Thermostats - Thermostat Selection Guide | |
| Air Conditioning Only – Split System | 99.9% of available low voltage thermostats will accommodate the Air Conditioning Only – Split System control. |
| Gas Furnace Only | 99.9% of available low voltage thermostats will accommodate the Gas Furnace Only control. |
| Oil Furnace Only | 99.9% of available low voltage thermostats will accommodate the Oil Furnace Only control. |
| Electric Furnace Only | 99.9% of available low voltage thermostats will accommodate the Electric Furnace Only control. |
| Boilers (Steam or Hot Water) | 99.9% of available low voltage thermostats will accommodate the Boilers (Steam or Hot Water) control. |
| Heat Pump Only | Be careful when selecting a thermostat for a heat pump. Not all thermostats support heat pumps so make sure you read the box of the thermostat to ensure you get a heat pump thermostat. |
| Heat Pump w/Auxiliary Heating (Electric, Gas, or Oil) | Be careful when selecting a thermostat for a heat pump. Not all thermostats support heat pumps so make sure you read the box of the thermostat to ensure you get a heat pump thermostat. See below for technical notes. |
| AC with Gas Furnace | Ensure the thermostat selected has air conditioning and gas furnace options available. See below for technical notes. |
| AC with Oil Furnace | Ensure the thermostat selected has air conditioning and oil furnace options available. See below for technical notes. |
| AC with Electric Furnace | Ensure the thermostat selected has air conditioning and electric furnace options available. See below for technical notes. |
| AC with Boiler (Steam or Hot Water) | Ensure the thermostat selected has air conditioning and boiler options available. Some thermostats may say heating only while others may be more specific and mention steam or hot water boiler systems. See below for technical notes. |
| All Package Unit Combinations | See various thermostat/equipment combination options for split system/stand-alone heating and air conditioning systems. |
| Multi-Stage Air Conditioning | This thermostat should have Y1 and Y2 terminals for multi-staging of cooling. This means you have an air conditioning system with two compressors or a single compressor that is capable of running at two different speeds or capacities. There is a temperature differential that will engage the second stage of this thermostat to start the second stage of cooling if needed. Usually, a 3-degree differential setting is typical for the second stage to kick in and provide additional cooling. Some thermostats offer you the ability to change this differential to suit your comfort level. |
| Multi-Stage Heating | This is the same as the multi-staging thermostat for air conditioners except this thermostat should have W1 and W2 terminals instead of Y1 and Y2 terminals. As with the Multi-staging air conditioning thermostat, the multi-staging heating thermostat will also have a differential of approximately 3 degrees before the second stage calls for heating. Some thermostats offer you the ability to change this differential to suit your comfort level. |
| Multi-Stage Heating and Air Conditioning | This thermostat will offer Y1, Y2, W1, and W2 terminals for multi-staging heating and air conditioning systems capable of multi-staging. See the Multi-staging heating and air conditioning above for further details on staging and temperature differentials with the thermostat. |
| Line Voltage Thermostats | |
| Electric Base Board Heating System | These thermostats are usually rated for line voltage operations and are rated by volts/amps of the system the thermostat controls. It is important that the proper selection is made for volts/amps to avoid problems. |
| Millivolt Thermostats | |
| Gas Logs or Fireplaces | Gas logs and some older forced air gas furnaces can work on a millivolt thermostat. To determine a millivolt thermostat is needed when making your thermostat selection refer to the owner’s manual or consult an HVAC professional. |
| Some Forced Air Furnaces (Older Models) | |
| Technical Note: It is important when selecting the proper thermostat to know if your system has a single transformer or a double transformer. Some split systems will have a transformer for the heating and a transformer for the air conditioning system. This will make a big difference in the type of thermostat you select. If the system has two transformers then the thermostat selected must have an RC and RH terminal to separate the circuits. | |
Hopefully, this chart will help you select the correct thermostat for your home and your new properly installed thermostat will give you years of comfort and energy savings.
Thermostat Selection Guide | Home Thermostat Replacement
Thermostat Selection Guide
I am replacing an old thermostat in my garage has 3 wires, red white and green. New thermostat only has 2 terminals. How do I hook up properly
Red is power. White is heat. Green is fan.
I have a gas furnace and outside electric AC unit. What brand and model of programable thermostat will automatically switch between furnace and AC as tempertures change throughout the day? This thermostat does not need to be a “smart” one or upgradabel for internet access.
Hello Bob, make sure to read the box for furnace/AC compatibility. Most thermostats sold these days are compatible with most systems but read the box to make sure. There is a long list of thermostats here if you want to take a look.
I have a LG la180hyv1 I would like to use LG dry contact for a third part number PDRYCB300 and want to know what wifi thermostat would work ?thanks
I attempted to find a technical manual for this unit and from what I looked at there is not much to go by for setting up something like this. I would use a relay that had a built-in delay and attached the thermostat to that. Sorry, but finding technical info for mini-splits is not easy. Usually, you have to find a factory rep that has attended the factory-sponsored classes.
I have a heat pump / air conditioner with gas heat as well. Current thermostat, I can put on ’emergency’ heat to bypass the electric and just run the gas heat. Replacing a thermostat, here are the wires in my current unit: C; EW1; W2; G; Y1; R; and O. What thermostat should I replace this with? Can I use the Honeywell RTH6350 unit? Thanks for your help!!!
looks like that model is a Honeywell heat pump thermostat and will work provided it is wired correctly using the proper procedures for thermostat wiring. We have an article giving you procedures for installing a thermostat here.
I have a sharkaire mini split unit I’m unsure of the type of thermostat I need
Minisplits typically use proprietary thermostats. Many come with their own remote control. You will have to contact the manufacturer for help with that one.