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Sustainability

Our first few months with a heat pump

It’s time for an update on my heat pump before what is likely to be a very expensive winter for everyone in the UK starts.

Here’s what we think of the heat pump now that it’s been outside our home for a few months.

Heat pump and hot water

I’ve been very impressed with our heat pump throughout the summer for our hot water. We had good water pressure before but our shower is much improved now. There are two reasons for this. Firstly a pump was put in to improve the pressure from the unit up into our old boiler cupboard as the system is no longer gravity fed. Secondly we have much better temperature control of our water now.

Our old boiler either gave out scolding hot water, or it’s ice cold equivalent. We still have the mixer taps on our shower, but we can now control the top temperature of our hot water far more easily and the hot water takes less time to come out of the tap too.

Heat pumps can heat your water to whatever temperature you like, but we’ve set it a bit lower than the default, with the immersion tank set to heat up the water once a week at 3am every Monday for one hour to get it to 55 degrees (and kill any Legionella and other bacteria in our system).

We basically have the water at the temperature we need and have largely eliminated the need to cool down the water too much. Not something we could have considered with a gas system.

For the first time since I’ve moved into my house I can set my own water temperature, not burn myself and waste less water waiting for it to warm up.

Heating

We put the heating one for one full day back in June to to check all the radiators worked. Although we later realised that the heat pump and thermostat had actually been coming on about 3 times a day in May/June based on the settings that the installer left us with. I turned the thermostat off and the heat pump has not been active since (save for our hot water).

We also had a bit of a scare one day after adjusting the system pressure when no water came out of our upstairs tap. We quickly realised this was due to a big pipe leak in the area and the effect on our system was a complete coincidence.

What it sounds like

The unit outside sounds like a very gentle fan when it’s warming our hot water. It will definitely be louder when it’s colder and working harder. We have heard it going full pace as part of its commissioning and it was fine to be honest. We can’t really hear it from indoors and we won’t be outside for long when it’s really cold.

The pumps, pipes and inverters inside the old boiler cupboard sound rather like our old boiler did only quieter, I work next to this all day and it’s fine. A new thing is that the heating system can be heard through the radiators ever so quietly. I’ll report on this more once we’re using it every day.

We no longer need to have a carbon monoxide monitor in the room where I work, so that’s nice.

Energy usage

We’re averaging about 10-12kWh for our daily total electricity usage at the moment (lighting, appliances and hot water) and of that in the summer 1kWh/day for heat pump usage alone (we know this because it has its own meter). On our current tariff, our total usage costs about £2.50 a day (with no heating). We work from home every day so this checks out.

Obviously this is going to cost a lot more over the winter.

Post install paperwork and compliance checks

We had a couple of additional checks from the Boiler Upgrade Scheme (BUS) where we had to sign some digital documents and provide proof of address and identity. This presumably to prevent fraud.

Ofgem selected us for a desk audit which basically means providing them with more paperwork, photographs serial numbers etc, about 20 documents in total. This is presumably to make sure something has been installed, done adequately and been completed. There was an optional step for them to visit our property, but we were not selected for this and our documents were sufficient.

The Microgeneration Certification Scheme (MCS) also called us separately to double check our contact details and to make sure we were happy with both the installer used and the installation work done.

Questions from others

Does the heat pump cool your house too?

No, most heat pumps that do this are air-to-air heat pumps. These are common in places where central heating are done by units high up on walls that put out air that can be heated or chilled. Most UK domestic heating is water based, so most of our heat pumps are air-to-water or ground-to-water so that existing piping and underfloor heating/radiators can be reused. So in short they can be used to cool your home if they’re the right type of heat pump, but these aren’t as common in the UK.

Does the heat pump output cold air in the summer to cool you down?

Our heatpump has been very inactive when it’s warm, only really coming on to top up our hot water, and when it’s warm this rarely needs to happen. So usually there is no cooling breeze in the garden – but I experienced this happening once on the last day of the UK 40 degree heatwave and it was lovely.

I need to find a way to automate our system so I get an alert when it switches on, so if one of us wants to cool down in the summer we can do this. I am looking at some solutions for this including Home Assistant.

Should the heat pump be put in the sun or shade?

So it can benefit from extra warmth? It will work with the ambient temperature it’s in. This wasn’t a factor mentioned in installation. The most important factors were a) having enough space around and in front of the unit b) us being happy with the location.

What about installation, and your research process?

I wrote about this in another post, check out my heat pump tag.

Next update will be either during, or post this coming expensive winter. Please let me know if you have any other questions.

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