Thermostat Selection Guide - This article will help you select the right type thermostat for the HVAC system you have installed.
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.
It is recommended if you do not know what you are doing or having any doubt what-so-ever 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
|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 note.|
|AC with Gas Furnace||Ensure the thermostat selected has air conditioning and gas furnace options available. See below for technical note.|
|AC with Oil Furnace||Ensure the thermostat selected has air conditioning and oil furnace options available. See below for technical note.|
|AC with Electric Furnace||Ensure the thermostat selected has air conditioning and electric furnace options available. See below for technical note.|
|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 note.|
|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 terminal 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 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 be made for volts/amps to avoid problems.|
|Gas Logs or Fireplaces||Gas logs and some older forced air gas furnaces can work on a millivolt thermostat. To determine a milivolt 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
Thermostat Selection Guide
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