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How to Wire a Heat Pump Thermostat? Everything You Need to Know

Views: 6298     Author: Site Editor     Publish Time: 2021-01-08      Origin: Site

The heat pump drives the compressor for heating and cooling. Your heating and air conditioning system is revitalized by connecting a heat pump to an internal heating band. The thermostat controls the full operation of the heat pump system installed with the optional heating tape.

The thermostat manufacturer's algorithms indicate the optimal times and intervals for the heat pump, possible heating levels for your model, the heating rod, and the speed of the indoor fan. The control parameters for your system can be found in the Thermostat Configuration menu, accessed through the switches defined by each thermostat model. Information on the parameters can be found in the heat pump's installation instructions and the heating tape.


Things You Will Need to Wire a Heat Pump Thermostat


Wire Strippers

Cutting Pliers

Plastic Cable Ties


Variants for Connecting a Heat Pump Thermostat

Heat pumps move the heat from one place to another. The switch between heating and cooling depends on the season and the thermostat setting. Besides, the air source heat pumps have backup heating methods for two reasons.


When the heat pump system starts defrosting, it needs a backup heat source.


The main method of backup or backup heating for heat pumps is electrical tape heaters. The second most common reserve heat source is a gas oven. Finally, these two different methods may require a separate connection of the heat pump thermostat.


Heat Pump Wire Labels

Name and connection of cable C - old cable C? This is a common thread that has caused indigestion and sleepless nights in many people. The reason for this is that most modern thermostats need or need a C-wire to work. The usual 24 V C cable comes from the control transformer and the above-mentioned R cable. Four-wire HVAC system control transformer. One side is also for the mains voltage in the transformer, and the other side is the 24 V control voltage that comes from the other side of the transformer.


To get a complete circuit, you need a source, path, and load. In this case, the transformer is the source, the R-wire and C-wire are the paths, and the thermostat is the load.


Designation and connection of cable R - Cable R is the 24 V hot cable of the 24 V control transformer. This is the way to enable control relays and connections in your system. The thermostat is just a switch, and the power from the transformer comes through this device.


The Wiring Problem C

The C-wire is generally dark blue in color.

This means that if you don't have the correct amount of wire in the thermostat, you will need to connect the new thermostat wire to the new thermostat. In other words, you have the right number of conductors for your new thermostat to work properly. A heat pump thermostat requires more connections than an air conditioning thermostat. This also provides the C-wire.


Other Names and Wires for R-wire Clips

You can't have two transformers feeding one thermostat. If you only have one transformer, you likely have a jumper wire (or copper tape) between the right and the RC terminal. If you don't have a jumper, the red wires will be disconnected. The filament transformer has a red wire that ends at RH. Besides, the cooling system's control transformer has a red cable that ends in the RC station.


Some people might wonder why they should use a single common thread, or C-thread, in this situation. The big question, especially from a beginner who started his career in HVAC. It shows that they are afraid. This is because all neutrals are (in most cases) the same. Unless it's too expensive, I advise the customer always to rewire a transformer. Most transformers on either system can handle the VA required to power all of the controls on both systems, and rewiring is straightforward (for me, at least).


Other Control Terminals and Cable Designations for Heat Pumps

Identify cable terminal Y - This color is usually a yellow wire and goes to terminal Y. In a heat pump, this is used for cooling. The compressor contactor is switched on in the condenser.


O wire label - This applies to the check valve in the condensing unit. The reversing valve converts the condenser from heating to cooling and back, depending on the thermostat setting.


Adjust Cable Clamp W - This color is usually white and goes to Clamp W. With the heat pump, this is an additional heat source. Whether electric heating strips or a gas oven (dual power), the W-Station controls this. This wire also works with air-handling equipment/ovens and condensers. The condenser defrosts the control panel automatically defrosts the system. When it goes into defrost mode, the backup heating is activated. In most cases, when changing the thermostat, you don't have to worry about wiring the capacitor.


Connect an Additional Thermostat to the Heat Pump Thermostat

In some cases, you have a system that requires deployment. Most residential layer systems are two-layer systems. In this case, you need a thermostat with a W2 connection and a Y2 connection. The colors of these connectors are different, but in most cases, W2 is black, and Y2 is light blue. Depending on the system, the W2 can be used for emergency heating, the backup heat source. It is sometimes called a backup heater and is used when there is a problem with the condensing unit.


In some cases, the thermostat terminal is labeled Aux / E / W2.

If your old thermostat used two separate wires and terminated them separately on the Aux and E terminals, use an extra wire and wire to bundle those wires together. Then connect the auxiliary cable to Aux / E / W2 *. * Always follow the manufacturer's wiring instructions. Manufacturers might have different wiring instructions to get it right.


It is seldom but still possible. If you have a traditional air conditioner or heat pump and an RC-RH bridge is in place, you only have one adapter, and you don't have to worry about two transformers in your system.


If you have operation problems, it is imperative to ensure that you have the same connections from the air treatment to the thermostat to the condensing unit. Also, use our other resources (other articles) here to troubleshoot thermostat issues.


Tips on How to Wire a Heat Pump Thermostat

The table above will help if you have a question about which thread color goes where. Thermostat cables come in handy. Colors like red for power supply and go to station R. As with other colors and stations. Depending on who finally connected the thermostat, they may not have followed the wires' color code.


Before removing the old wires, take a photo of the wires and end up on the old thermostat's lower base. Use your phone to take the photo for future reference.


Always ensure that the power supply is switched off before attempting any wiring. If you forget to do this, the transformer may burn out or trip the LV circuit breaker. Or light the low-voltage fuse.


For a full list of colors, nature, and purpose, see here - Heat Pump Thermostat Wire Colors.

Heat Pump Thermostat Wire Colors

Your temperature may differ from that described here. The heat pump circuit diagram above covers about 90% of the heat pump thermostat.


Note: Some thermostats may have a feature called Emergency Temperature that, when set, turns off the heat pump. Then it activates the heat from the belt, which becomes the main heating source. This function should only be used for a limited period of time as the energy costs are usually higher than those of a heat pump system. The station used is E.


Look out for the following features that are found in most modern programmable thermostats.


  • Low voltage test that indicates the incoming power is low.

  • Error codes that tell you why your system is not working properly.

  • A compressor downtime of at least 3 minutes serves to avoid a short circuit in the compressor. A short compressor cycle shortens its life.

  • Programmable day and night settings for the target temperature.

  • Weekend settings and vacation discount functions.

  • The ability to check the thermostat status and control parameters remotely via a smartphone or computer. This feature increases the cost of the thermostat.


Conclusion on How to Wire a Heat Pump Thermostat

Always follow the thermostat manufacturer's wiring and setup instructions as a final step. A newly installed thermostat requires a special heat pump configuration. The instruction manual is intended to help you navigate the settings and make the appropriate changes to the thermostat to function properly as a heat pump.


There are other wire configurations for connecting a heat pump thermostat, but these are the basics. Hopefully, this has been explained so that you can better understand the wiring. If you have a humidifier and an electronic air filter for cleaner air, additional cables are required for these devices. Follow the basic wiring instructions for the thermostat for these wires. If you are confused, contact a specialist. Also, it would be cheaper for a professional HVAC technician to do this for you rather than burn something because of poor wiring in the long run.

Thermostat and Heat Pump Wiring Instructions---only for SPRSUN products

1. Appearance of thermostat


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