Air Source Heat Pump

rangor gubbins · 11 Mar 2018 at 15:11

About to start a house refurb including putting in underfloor heating throughout.
Our heating is currently provided by an old Worcester Bosch boiler running off an LPG tank sat in the drive. Its pretty expensive to run, the tank looks horrible, and is in a stupid location. So we are planning to get rid of the LPG tank and boiler and install an Air Source Heat Pump to supply our heating and hot water.
Anyone have any experience / advice with an ASHP?

We're also thinking about install photovoltaics on the roof to help offset the extra electricity usage, but as we are out all day at work I'm sure how much benefit the PVs will give because maximum heat demand will be when the sun is either not yet up or has gone to bed.

rangor gubbins · 11 Mar 2018 at 20:47

Thanks for the info.
I was hoping people would say they are using them to heat their home and hot water and it all works great and is cost effective.
I've looked into battery storage, but seems quite expensive at the moment. Powerwall and the cheaper Powervault.
We don't have enough accessible ground space for a ground source heat pump so would have to drill bore holes which hugely increases installation cost.

rangor gubbins · 12 Mar 2018 at 19:20

Great info, thanks people!
As part of the house refurb we will be greatly improving the insulation in the roof, floor, windows and walls, so I'm hoping the running costs of the air source heat pump will not be too bad.

zooankski said:
When i moved to my last home the "affordable houses" all had air source heat pumps.
They make a horrible low pitch humming noise, especially in cold weather....

Do you remember what make and model those heat pumps were?

rangor gubbins · 13 Mar 2018 at 08:32

Kimi said:
I install them and also have one myself. I've got a Mitsubishi Ecodan. If you're off gas, then it's pretty much perfect. Currently getting 10k back from the RHI scheme which has covered all my costs.

Poster above who has the legionella cycle set to every 3 days, that should be set to once a week. To 60c. That will improve your efficiency.

Happy to help with any questions.

Awesome, thanks Kimi. the company we've contacted have recommended we install a Nibe - F2040 12kW + SMO20 + VST 05, with Nibe UKV40 buffer vessel and a Joule - Cyclone 250 litre Cylinder, and no hydrobox (whatever that is). We only have single phase electricity supply available and i understand this limits us slightly in what we can install.
How does Nibe compare with the Ecodan?
Do you think he 250 l cylinder is big enough for a 4 bedroom house? My partner is fond of long hot showers and she's a bit concerned that the ASHP will struggle to keep up.
Is there a cheap way of maximising the benefits of having an ASHP + photovoltaics? e.g. setting the heat pump to come on in the middle of the day?

rangor gubbins · 14 Mar 2018 at 07:57

Interesting thoughts, thanks Kimi.
Can you either post or send me via Trust the name of your company?

rangor gubbins · 26 Feb 2019 at 17:42

Yes we put an ASHP in - a Nibe F2040. It's been in since beginning of Dec, but as we're still doing the house refurb and are not properly living in the house yet we don't know how the whole system will work out (cost to run!).
With the underfloor heating and insulation between the pipes and concrete sub-floor, plus insulated plasterboard on the walls, and lots of insulation in the roof, we should have a pretty well insulated house, and the ASHP does seem to be able to warm the house well on the few test runs I've done so far. I will be able to tell you more next winter!!

I did read a bit about air - air heat pumps and they sound pretty good. I found an interesting (but slightly old now) article of a case study of ASHP and solar panels. Google 2013-RS-McIntosh-Solar-HP.pdf
One big benefit for us is having the under floor heating as its so much nicer to heat the house rather than radiators.

I think you can still get grant (search for Renewable Heat Incentive) for installing an ASHP for a wet system, but i don't know if you can get grants for Air-Air HP systems.

As Kiwi mentioned earlier, just make sure you use a reputable MCS certified installer who knows how to do a proper Heat Loss Calculation. This is the key to working out if a heat pump is suitable.