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Thermostats for Heat Pumps

Thermostats for Heating Systems

Thermostats for Heat Pumps

Electronic Thermostats

Programmable heat pump thermostats are available today from most heat pump manufacturers and their representatives. Unlike conventional thermostats, these thermostats achieve savings from temperature setback during unoccupied periods, or overnight. Although this is accomplished in different ways by different manufacturers, the heat pump brings the house back to the desired temperature level with or without minimal supplementary heating. For those accustomed to thermostat setback and programmable thermostats, this may be a worthwhile investment. Other features available with some of these electronic thermostats include the following:

  • Programmable control to allow for user selection of automatic heat pump or fan-only operation, by time of day and day of the week.
  • Improved temperature control, as compared to conventional thermostats.
  • No need for outdoor thermostats, as the electronic thermostat calls for supplementary heat only when needed.
  • No need for an outdoor thermostat control on add-on heat pumps.

Setback savings of 10 percent are possible, with one setback period of eight hours each day in most Canadian locations. Two such periods per day can result in savings of 15 to 20 percent.

Conventional Thermostats

Most residential heat pump systems are installed with a "two-stage heat/one-stage cool" indoor thermostat. Stage one calls for heat from the heat pump if the temperature falls below the preset level. Stage two calls for heat from the supplementary heating system if the indoor temperature continues to fall below the desired temperature.

The most common type of thermostat used is the "set and forget" type. The installer consults with you prior to setting the desired temperature. Once this is done, you can forget about the thermostat; it will automatically switch the system from heating to cooling mode or vice versa.

There are two types of outdoor thermostats used with these systems. The first type controls the operation of the electric resistance supplementary heating system. This is the same type of thermostat that is used with an electric furnace. It turns on various stages of heaters as the outdoor temperature drops progressively lower. This ensures that the correct amount of supplementary heat is provided in response to outdoor conditions, which maximizes efficiency and saves you money. The second type simply shuts off the air-source heat pump when the outdoor temperature falls below a specified level.

Thermostat setback may not yield the same kind of benefits with heat pump systems as with more conventional heating systems. Depending upon the amount of the setback and temperature drop, the heat pump may not be able to supply all of the heat required to bring the temperature back up to the desired level on short notice. This may mean that the supplementary heating system operates until the heat pump "catches up." This will reduce the savings that you might have expected to achieve by installing the heat pump.

Thermostats for Heating Systems

Programmable Thermostats

The easiest way to save heating dollars is to lower the temperature setting on your house thermostat. As a general rule, you will save 2 percent on your heating bill for every 1°C you turn down the thermostat overnight.

A programmable thermostat will adjust your home’s temperature automatically. These thermostats have a mechanical or electronic timer that allows you to preset household temperatures for specific periods of the day and night.

You could program the thermostat to reduce the temperature a short while before you go to bed and to raise it again before you get up in the morning. You could also program it to reduce the temperature for any period during the day when the house is unoccupied and to restore the temperature shortly before you return. A good guide is to have the temperature set at 17°C (63°F) when you are sleeping or not at home and at 20°C (68°F) when you are awake and home.

Experiment with the unit until you find the most comfortable and economical routine for you and your family.

Programmable thermostats offer at least four daily temperature settings (such as wake, day, evening, sleep) for at least two different program periods (for example, weekdays and weekends). A hold feature allows you to temporarily override the program for a period such as a vacation. When used properly, programmable thermostats can save you 10 to 15 percent on your heating bills.

Many thermostats offer additional features that allow you to:

  • store and repeat additional daily settings that can be run and changed without affecting the regular settings
  • store more than four daily temperature settings
  • adjust heating and cooling turn-on times in response to outside temperature changes

More sophisticated electronic and self-tuning thermostats are also being developed. These sensitive devices help reduce temperature swings from an average range of between 1.5°C and 2°C to a range of between 0.5°C and 1°C. As a result, the heating system turns on and off as close to the required temperatures as possible. Energy savings from these mechanisms can vary, but they usually enhance comfort.

Zone control

You can also reduce energy use through zone control. In a forced-air heating system, this involves placing dampers in duct passages and controlling them with separate thermostats in different areas of the house.

Zone control is also available for hydronic (hot water) heating systems. With it, temperatures of individual rooms are regulated by thermostat-controlled valves on each radiator.

A plumbing and heating contractor can provide more information about zone control and can install the required equipment when the heating system is installed.