Air to Air Heat Pump

We are looking at an air to air heat pump.

We have a choice of 2 types of gas R410a and R32. I have been trying to work out how efficient each gas is and what the average running cost is per year. Have any of you done the calcs?

I have read that R32 is the newer gas and a low GWP.

If we look at these 2 units



They is a diffrence of 437kWh/a according to the Annual Energy Consumption, so how can both units be A++?

You must be VERY careful with these classifications.
First, all the data you see on the spec are for a specific situation (air temperature, humidity, ….) and depending where you live, you can have massive differences in energy costs.
That’s specially the case for air-air heat pump.
For example, for my water-water heat pump, I’ve these values for a specific source temperature:

  • if I heat the water till 35°C, the COP is 4,54
  • if I heat the water till 65°C, the COP is 2,2.


In theory R32 is supposed to be a little more efficient than R410A as a refrigerant so that might go some way to explain some of the differences between these two machines and their quoted efficiencies.

Thing is, how they are run in the real world makes all the difference and quoted COP figures vs real life are always going to be a bit different. Nobody lives in a humidity controlled thermal test chamber!

What I would say though, as you’re looking at split systems, they have a very slightly higher chance of a refrigeration leak in my opinion than a monoblock air to water system. If a refrigeration leak occurs, it is better to leak out R32 into the environment than R410A. A fridge leak is very unlikely to happen but worth a thought perhaps.

I don’t think enough attention is paid to the GWP of different refrigerants. I know there’s a move to use Propane R290 in some new monoblock air to water machines. A GWP of only 3! Might not be seen in split systems for a while yet.

R290 GWP of 3
ammonia as a refrigerant is the best 3-10% more efficient then other refrigerants and cheaper and does not break down… you have some old fridges and freezers that are over 50 years old and still working that operate on ammonia as good as the day they bought it ( they get really really cold too). and a GWP & ODP of 0 to boot … some of the refrigerants you have now start to break down after 7 years. and can not just simply topped up. have to flushed and then refilled… but it all about time obsolescence – nothing built to last forever now

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I believe ammonia is used in breweries in the UK as the refrigerant - presumably for the same reasons.

most commercial cooling are going ammonia now or should I say again. very little in the residential market currently other then some specialty fridges and freezers ( but i see some Chinese and Russian companies are starting build water to water r717 heat pumps )

  • 20% less build material
  • cheaper to operate
  • and much much cheaper to charge the system.

i think now the price is +40% cheaper then any other system it the big commercial systems

I had read all about the different gas types and the impact if they is a leak. I was trying to work how how much more efficient the r32 gas was on a running cost point of view. after talking with some and using the calcs from part L Building regs. based on a 4kW unit a r32 unit saves £19 per year over a r410a system and this does not change much when you move to a 12kW unit