Do heat pump work? It’s all in the installation

We’ve had our heat pump for four years. It’s worked fine and we’ve been saving 75% of our energy usage – so nothing to complain about there. As far we knew, all was as it should be.

Sure, there were cool patches in the day, but it was so much better than our house had been for the past 43 years, who were we to complain? We knew next to nothing about heat pumps, so assumed this was to be expected. We didn’t know what we didn’t know and we had no idea of the questions to ask.

Why so many complaints?

The poor maligned heat pump! It’s just a bit of kit like any other. It’s been working in Scandinavia for decades and we can’t say those are warm countries. UK has nothing on Sweden or Norway.

Yet the media is full of heat pump misery:

• They cost too much to run

• our house will be cold

• You won’t have enough hot water

• They’re too noisy

• Your neighbours will complain

The list goes on and a lot of people are buying into the rhetoric.

But it’s not the first time we’ve gone into overdrive about changes in how we use our homes. I remember the resistance of my grandparents when the idea of central heating was first mooted:

• You don’t need to be warm everywhere in the house

• All that warmth isn’t good for you.

• Bugs will grow in the house.

• I’ve been perfectly fine living in a cold house.

• What’s the matter with a coal fire?

So we’re just back there again. Time to change and some people will always push back.

Yet there are problems

People do report high energy bills, they do say they’re cold in their home with insufficient hot water, they do say their pump is noisy.

Here’s what I found out from my own experience:

Suppliers aren’t trained well enough. Optimising the pump for energy efficiency isn’t a standard part of the training, so they have to opt in and pay more for that information. Home owners don’t realise they have to use the pump differently to the gas boiler, so they cost themselves money.

We were text book – inadequate heat pump owners.

Comments from the Everything Electric film about what we’d done to the house told me in no uncertain terms that we were doing it all wrong. So I set out to understand and do something about it.

Heat loss calculation

I got a Heat Geek trained installer in to check how ours was doing. They did a fresh heat loss calculation assessing:

• size of the house

• energy usage

• fabric of the house - insulation levels throughout

• ventilation flow

• structure – suspended or concrete floors

I’ve learned that, while there is a formula to calculate heat loss, experience plays a part. An experienced heat pump installer will get a ‘feel’ for the needs of a home that backs up the numbers.

The findings

It was an eye opener.

Pump size: Turns out the pump size we have is too big. Initially we were due to have a 12.5 kw pump. John was sure that was too big and in conversation it was decided we should have an 8.5kw. Now it turns out we could have had a 4kw pump. This is important for energy efficiency. When a pump is too big, it ‘cycles’ which means it keeps going on and off – and this uses energy. If it’s too small, it has to work too hard. Both cause additional wear and tear on the pump.

Thermostats: there is a specific thermostatic system that works for heat pumps. And it’s different to the normal Nest / Hive systems that work so well with gas boilers. Zoning with room thermostats and individual radiator thermostats makes life a lot more difficult for the heat pump, so it ends up working too hard.

Additional pumps: for some reason we had a pump on the heat pump itself to serve the radiators and another on the underfloor heating manifold. Both were confusing the system and making more work.

We had also removed radiators when we were still using the heat pump like a gas boiler so those had to go back.

It’s all happening

Today is the day. Now the final tweaks to the system are being done.

• Extra pumps removed

• Whole house thermostat system disabled. (but left in place in case we wanted to use it again at some point in the future. Can’t see why we would, but better than having holes in the walls!)

• Piping simplified on the heat pump

• New thermostat system set up

Will we see a difference?

Hard to know at this stage. We’ll have to compare energy bills. Hoping Octopus can help me do this! And we may need to wait for a year from now to really see.

But at least now we know that it’s all working correctly. And we have already felt a difference from just using it right ourselves. No more cold spells in the day and no idea what the weather has been like this winter.

To find out more about retrofit overall, including the basics of heat pumps, look at What the Builder Won’t Tell You and Beginner’s Guide to Eco Renovation. I wrote both to give you the basics in plain English so you know the right questions to ask at the outset in order to get the home you want, without having to do remedial work like us!

Any questions, let me know