Ultimate Thermostat Buying Guide 2019

Ultimate Thermostat Buying Guide 2019

This thermostat shopping for information gives data that may help you in deciding on a thermostat that correctly controls the kind of HVAC system you could have and has the efficiency options you need. Many thermostats are additionally known as controls, since they do greater than merely sense temperature and switch the system on or off in response. Controls are designed to optimize indoor consolation, comfort and power effectivity. Right here’s the place we’re going on this thermostat management shopping for information:

  • Half 1 is about thermostat compatibility together with your system
  • Half 2 is concerning the options you may want and whether or not they’re value the additional expense
  • Half three is about fashionable conventional thermostat and WIFI sensible thermostat critiques

Let’s do that!

Half 1: Thermostat Fundamentals and Your HVAC System

Every thermostat is designed to work with a selected system kind. There are a number of areas during which compatibility have to be ensured or the thermostat gained’t work or gained’t let you get the perfect efficiency out of your heating and air-con.

Thermostat Voltage


HVAC techniques will be categorized by the kind of energy they require:

  • 110V or 240V energy: These are known as high-voltage or line-voltage techniques and embrace electrical furnaces and electrical baseboard techniques.
  • 24V energy: These are known as low-voltage techniques and embrace most cut up and package deal techniques with fuel or oil furnaces, air conditioners, warmth pumps and boilers.
  • Millivolt energy: These are gas-fired heaters that don’t use electrical energy as a result of they don’t have a blower fan. Most are used for supplemental warmth or area heating.

Every HVAC system kind requires a thermostat suitable with the facility it makes use of. As famous, most residential heating and air-con techniques use 24V energy, and these are the thermostats we talk about in the remainder of this text. Nevertheless, there are totally different classes of 24V thermostat, and the subsequent part discusses matching your HVAC system to the best 24V thermostat.

Staged Heating and Cooling: What it Means in your Thermostat Buy

For years, furnaces have been manufactured with one working mode. They have been both on and working at full capability or they have been off. When central air-con was launched, it was the identical. This is called single-stage heating and cooling, 100% capability being the one stage. At present, single-stage furnaces, warmth pumps and ACs are nonetheless produced, however there are two different efficiency tiers.


Listed here are all three:

  • Single-stage techniques, as outlined above, are made by each HVAC model.
  • Two-stage techniques provide two levels of heating and cooling. The primary stage is normally about 65% capability, and second-stage is 100% capability. The models run on the primary stage more often than not. Some great benefits of decrease capability embrace higher effectivity, quieter efficiency and temperatures which can be extra balanced. When the home cools off or warms quickly resulting from altering outside temperatures, the system may must run on 100% capability for a cycle to compensate. In case you change the thermostat setting by a number of levels, second-stage/full-capacity heating or cooling may also be required. Each model makes two-stage furnaces, ACs and warmth pumps.
  • Variable capability techniques function at any share of capability between about 40% and 100%. This potential takes the efficiency benefits of two-stage to the subsequent degree – probably the most environment friendly, quietest and most exact heating and cooling. Initially, solely Service made variable-capacity tools, which can also be known as modulating and variable-speed efficiency. Then, Lennox, Trane, Heil, Goodman, Armstrong and different main manufacturers started producing it, although at this writing there are nonetheless just a few that don’t.

The query is, how does staged heating and cooling have an effect on thermostat alternative? The reply is that thermostats are made in single-stage, two-stage and variable-capacity fashions too.

  • Single-stage thermostats: These fashions help single-stage working. Because of this they accommodate one wire for heating, normally labeled W or W1, and one wire for cooling, usually Y or Y1. Different wires accommodate totally different options equivalent to 24V energy, the fan or a standard wire, briefly mentioned later.
  • Two-stage thermostats: These models have terminals to accommodate two heating wires, W1 and W2, and two AC wires, Y1 and Y2, plus energy, fan, widespread wire and probably further capabilities equivalent to a reversing valve for a warmth pump. The thermostat makes use of its temperature sensor to find out if first-stage heating or cooling is ample to take care of the specified indoor temperature or if the second stage is required. It sends the heating or cooling sign through the suitable wire, for instance, Y1 or Y2.
  • Variable-capacity/Speaking thermostats: These models are a special breed of the thermostat. They’re known as speaking thermostats, and we’ve accomplished a information known as HVAC System: Speaking vs Non-communicating that spells out the variations. For our functions, it’s sufficient right here to say that single-stage and two-stage thermostats are non-communicating whereas thermostats that accommodate variable-capacity techniques have to be speaking.

Fairly than having wires that give direct alerts for first or second stage heating or cooling and wires for different efficiency options, speaking thermostats are constructed with simply 4 wires: A single wire for heating, a single wire for cooling and two wires that present energy and permit the parts and the thermostat to “talk.” This implies the parts and temperature sensors ship data to the thermostat, and the thermostat responds by controlling exactly how a lot heating or air-con is required to maintain the house on the temperature desired with little variation.

Learn how to Verify Compatibility for Present HVAC System

When changing a thermostat, step one is to know what heating and cooling levels your HVAC system is supplied for. When you do, you’ll be able to choose an acceptable alternative.

Most non-communicating HVAC techniques have as much as 12 wires coming from the furnace or air handler to the situation the thermostat is mounted. You may decide your system capabilities by checking what wires are linked to the thermostat. The others are most likely coiled collectively. Verify your system capabilities with the following tips:

  • Take away the thermostat cowl from the mounting bracket to reveal the wires and wire terminals
  • W (white) is used for heating: If W (or W1) is the one W terminal with a wire linked, you could have a single-stage furnace or warmth pump
  • If W (or W1) and W2 are linked, you could have a two-stage furnace or warmth pump
  • Y (yellow) is used for cooling: If Y (or Y1) is the one Y terminal with a wire linked, you could have a single-stage AC or warmth pump
  • If Y (or Y1) and Y2 are linked, you could have a two-stage AC or warmth pump
  • Notice: When you’ve got a warmth pump, then it would have only one W and one Y terminal linked or each W and Y terminals, not one W and two Y’s or vice-versa

There might be different wires linked, both some or all the next:

Wire Colours
Wiring Capabilities
Y Yellow
Y2 Mild Blue/Different Colours
2 Stage Cooling
W White
W2 Brown/Different Colours 2 Stage Heating
G Inexperienced Indoor Fan/Air Handler Fan
C Blue/Black Widespread Wire
R Pink 24V Energy
RC Pink 24V Energy
E No Common Shade Emergency/Backup Electrical Warmth in an Air Handler
X/AUX No Common Shade Auxiliary Heating
B Darkish Blue Reverse Valve For Heating
O Orange Reverse Valve For Cooling
S1/S2 No Common Shade For Out of doors Unit

C Wire Situation

90% thermostats (particularly for WIFI thermostat) available in the market want a C wire to get working. If you can’t discover C wire in your present system, no worries. Verify our latest article: What If I don’t Have a Wire to discover a correct solution to get C wire again.

Do You Have a Speaking HVAC System?

In case you open the thermostat and see solely 4 wires, you might need a speaking thermostat. Widespread terminal connections are one every white, yellow, inexperienced and purple. That may trigger confusion as a result of the identical 4 wire connections can be a single-stage system.

The following pointers will help you in figuring out whether or not a system with a four-wire thermostat is a single-stage or speaking system:

  • At present, solely producers of furnaces, ACs and warmth pumps make speaking thermostats, so if yours is a third-party model like Honeywell, Emerson, White-Rodgers, GE, Ecobee, Lux, Geo or WiserAir, it isn’t a speaking thermostat, and your system is a single-stage system
  • If the thermostat is made by the identical HVAC producer because the furnace, then it ought to have one among these names:
  • Amana, Goodman and Daikin ComfortNet
  • Armstrong Air Consolation Sync
  • Bryant Evolution
  • Service Infinity
  • Coleman Echelon
  • Heil, Comfortmaker, Hold Ceremony and others Observer
  • Lennox iComfort
  • Luxaire Acclimate
  • Maytag, Tappan, Westinghouse, Nu-Tone or Broan iQ Drive
  • Rheem and Ruud Consolation Management System
  • Trane and American Normal ComfortLink II
  • York Affinity

For extra details about speaking, you’ll be able to seek advice from our earlier information: HVAC System: Speaking vs Non-communicating

Shopping for a Appropriate Thermostat

When you’ve decided the capabilities of your present system, the remaining is simple. There are 3 ways to verify the thermostat you purchase is suitable with the efficiency of your heating and air-con system:

1). Learn Product Reviews Evaluate the thermostat packaging or product description on-line. It can say “Works with 1 Stage warmth or cool” or “Works with 2 Stage or multi-stage warmth or cool.” Thermostats that help two-stage heating and cooling can be utilized with single-stage tools.

2). Use the compatibility checker on the producer’s web site, like this one for the ecobee thermostat. You’ll be proven a chart and requested to pick out the colours of the wires your present thermostat has linked to it. If you submit the data, the web page will let you know whether or not its suitable and in the event you want something further. Notice that if in case you have the four-wire single-stage heating and cooling setup, the compatibility checker gained’t be capable to decide whether or not it’s a single-state or speaking system. Ecobee’s website asks you to take an image of the wiring on the thermostat and e-mail it to Ecobee customer support for dedication.

three). Purchase a thermostat from an area vendor that sells and installs the model of kit you could have.

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