Interested in a Heat Pump?

Absolute Zero is -273˚C. It's the coldest temperature possible.

But any temperature above that and there is some thermal energy present.

This is how heat pumps can extract heat from low temperatures, even something like -15˚C. There is still heat energy in the air. Getting that thermal energy out is the trick of the technology. Heat pumps are getting better and better though and now many people are making the switch to supply heat to their homes and businesses.

Brief Description of Heat Pumps

Heat pumps have been around for many years, and became most famous as air conditioners and GeoThermal systems, but they are really the same technology as a refrigerator as well. The secret is the compressor.

Basically a gas is circulated inside the heat pump, and that gas can be compressed, which raises the temperature of the gas. 

Basic Example: Outside temperature of 0˚C, can be compressed to be 50˚C. Then this 50˚C gas flows through a pipe and it will give off heat to the air around the pipe. The air in your home is circulated around the hot pipe, heated, and then sent back into your house, having been warmed up several degrees. The main pipe continues in the heat pump to an expansion valve where the 'compression' is released and the internal gas is back to a lower pressure, and maybe -4˚C instead of 0˚C (or colder, even liquid form), having lost some of its heat energy.

A Heat Pump needs electricity to run the compressor, to circulate the gas it is compressing, and to blow air around as it absorbs and releases the heated air. However, these systems will produce about 3 units of heat for every unit of electricity it consumes, referred to as a 3.0 COP (coefficient of performance). So compared to baseboard heating which runs close to 100% efficient, heat pumps run at what is referred to as 300% efficient. 

Another way to look at this is that if you heat with baseboard heaters, you could heat with a heat pump for 1/3 the electricity cost.

The efficiency of a heat pump gets worse as the outside temperature gets colder though. Here's a graph showing a particular model as an example (Source Article) There are also many different types of heat pump.

Note: 0˚F = -17.8˚C and  60˚F = 15.6˚C

It should also be noted that current models of heat pumps have a low temperature at which they loose their effectiveness. (eg: the author's heat pump is rated to work down to -27˚C)

Considerations for Switching to a Heat Pump

1) Installation Cost

Actual installation costs can vary tremendously based on your home and current heating situation. If you have a furnace with forced air through vents, there is a heat pump that can replace that. However, if your furnace is in good condition and will run well for years it is likely not cost effective to install a heat pump yet. 

Geothermal heat pumps are very expensive to install, and require either a large ground area or deep drilling, but generally give a COP over 4.0 so they are very efficient and give cost savings in the long run.

Keep in mind that there are grants available to help make the switch as well, from propane and even more from oil. Contact the CAC if you want help of advice on this, or read these old posts.

2) Cooling

Heat pumps also provide cooling in the summer so they will replace an air conditioner if you have one. They are essentially the same thing as an air conditioner, but with the added bonus of heat in the winter.

3) Coldest Part of Winter

On Manitoulin we usually have several days below -20˚C in the winter and current heat pumps become less effective at these temperatures. The colder it gets, the more electricity the heat pump will need to compress the air and get heat to your home. In northern climates it's advisable to keep a backup option available for the coldest days such as a wood stove, or electric baseboard heaters to help with the heating your home when it's really cold.

4) Comfort

Generally a heat pump is quieter than a furnace and provides better air filtration. The air filters in heat pumps will vary depending on the type, but they are generally better than a furnace air filter, and can be washed instead of being replaced as disposable.

5) Future Cost

It's hard to predict the future, but most experts think that the cost of propane will go up faster than the cost of electricity, and oil may be even worse for costs. This is one of the leading factors for why many people are switching to heat pumps recently. Moving away from fossil fuel burning is also a major improvement to help fight climate change, who's future cost could be much higher than just utility bills.