What Size Heat Pump Do I Really Need?

Cheryl asks: My house is very cold in winter.  We currently only use an electric fan heater so our power bills have been through the roof! I’m looking at getting a heat pump.  How do I work out the correct size of heat pump that I need?

Hi Cheryl. Tell me about it – electric fan heaters are a nightmare to pay for. And what’s worse is they don’t keep you as warm as a good heat pump can. Rest assured knowing that this winter you can be nice and toasty with a new heat pump.

It’s good that you’re thinking ahead to heat pump sizing. The only way you can know for sure what size heat pump you should get is to talk to an expert. They will be able to determine the required cooling capacity for your home. After this, the heating capacity of your home is determined – this is usually quite close to the cooling capacity.

In laymans terms, an expert will determine just how hot or cool your home could be. They then take this information and compare it to psychometric charts provided by heat pump manufacturers. A basic formula is used to determine heating capacity relative to the outside temperature.

While you can use a chart to determine your heat pump size, this is highly discouraged. Rather a load calculation should be used to determine a detailed analysis for proper heat pump sizing. I’d recommend using Energy Wise‘s calculator. Before you do that, you should determine:

  • The type of room
  • Any insulation
  • The number of external walls
  • Window size in room
  • Room area in meters squared

But you see, even this isn’t always straightforward. Here’s an interesting video on why size shouldn’t be based on square meters:

So there is a lot to consider when getting your heat pump sized. More than you might have initially thought! If it seems like you won’t get through all these calculations before winter, it’s a great idea to contact an expert.

If you live in Auckland try Goldstar Heat Pumps, providers of Auckland heat pumps. This saves you the fuss of measuring windows and calculating your room area! I hope you manage to get the perfect heat pump for your room before winter strikes, Cheryl.