Air Source Heat pump, anyone had one?

[BigDecisionsLittleTime]

Our ancient oil fired boiler needs replacing. Don't really want to continue with oil.

From research seems like this is the best option, also added bonus of RHI scheme if we do it before March next year (I think!)

I've read so much about it all and I'm still quite confused. I'm getting cavity walls and loft insulated now before getting measured up for a heat pump, understand some radiators might need increasing. Appreciate it works best with wet underfloor heating, but we can't afford that just now. Read that mistubishi made pumps are good.

Does anyone have experience of this, any dos and don'ts? Is hot water still good? Does your electricity bill sky rocket?

Thank you

@Upupupintheair thank you

You have a programmer so you can programme it not to come on at night. No idea what the whooshing noise you describe is — do you mean that the pump is on and pumping hot water to the radiators? You should just be able to turn the whole system off at night, If it's been installed by a plumber and not a trained ASHP engineer then that's the problem. ASHPs need careful balancing: they're not easy to install properly. Has your 'plumber' been trained by Mitsubishi?

If your heating system has been installed using micribore — very narrow pipe rather than the standard 0.5 inch or 15mm — then yes, from what I understand that could affect the flow of hot water to your radiator and mean that the whole system is under stress. Don't think it makes it noisy though. What you're hearing is a pump switching on and starting the water circulation, probably.

£10-12k for underfloor and radiators and a heat pump and hot water cylinder is too good to be true.

Another Mishubishi here! Changed from oil last year as our 23 year old boiler was getting unreliable. We also needed a new water tank as we were getting some leaks. In retrospect, I wish we had PV panels linked to our tank fitted. ( It may not have been possible as we have a microbore system) During lockdown, with an extra adult in the house and his having looong showers, we have sometimes had to boost the hot water.
We had some radiators replaced- but they were ones we had always thought were undersized, and those rooms are toasty warm now, where they weren't previously.
We checked with Which trusted trader for an installer, and went for one who were plumbers who moved into ASHP rather than a more local company who are primarily solar panel companies.

@Shedbuilder trust me it’s not too good to be true, granted we ordered in 2018 and it was fitted in 2019, I’ve dug out the invoice from my emails and it was:

£9532 for the supply and fit of the mistubshi 11kw heat pump and tank (plus wireless remotes, installations and certificates etc).
£3129 for the supply and fit of the radiators and wet UFH downstairs.

All inclusive of 5% vat.

Total £12,661

@Shedbuilder thanks. Yes the programmer is programmed not to come on at night. The installer has been back twice to set this for us. However despite that, the pump turns on at night and starts pumping cold water to all the radiators. Which sounds quite noisy. The unit outside isn’t on, just the pump inside. The installer is Mitsubishi trained and has supposedly worked with ASHP for a good while but he doesn’t seem to know why it’s coming on at night when it’s been programmed not to. Come to think of it, the actual ASHP ‘expert’ didn’t fit the unit, he brought in another guy to do that. I assumed this guy would be trained to instal Mitsubishi ASHP, but now I’m questioning it.
I get up and manually turn the unit off when it comes on at night at the moment which seems a bit ridiculous especially as I’m pretty sure your meant to leave it on all the time.
Anyway, thanks for responding. My main query was whether my unit was working properly and I just had to accept the night time noise or whether something isn’t right with it. Sounds like it needs sorting out.

I’ve fitted under heating in a house once, it was a monumental amount of work digging all the floors out deep enough to get the required amount hardcore,insulation,screed in , and it cost a lot more than 3 grand. That didn’t included the floor covering.

[quote Upupupintheair]@Shedbuilder trust me it’s not too good to be true, granted we ordered in 2018 and it was fitted in 2019, I’ve dug out the invoice from my emails and it was:

£9532 for the supply and fit of the mistubshi 11kw heat pump and tank (plus wireless remotes, installations and certificates etc).
£3129 for the supply and fit of the radiators and wet UFH downstairs.

All inclusive of 5% vat.

Total £12,661 [/quote]
For a start, only the heat pump is 5% VAT: the underfloor heating and radiators aren't renewables, so would have been 20% VAT.

Presume you have overlay underfloor heating, not excavation, insulation, pipes laid and screed, plus new flooring over the top? Even so, someone was either desperate for turnover or priced up wrong, because there's not a penny of profit in that if they a) paying decent rates to experienced/qualified installers and b) they are MCS accredited (with all the checks and liabilities and paperwork costs involved in being part of that scheme) and properly insured.

Is the company that installed the system still in business? I'd be surprised, frankly.

Meant to add that I'm only saying this because I think we should all be heading in this direction — alternatives to oil and gas — but I think it's counter-productive when people cite unrealistically low costs. It's not cheap, moving to renewables, and IMO it's not helpful to pretend it is.

PP mentioned wishing they'd have PV connected to their ASHP. PV works indepdent of ASHPs and you can have PV installed at any time. PV supplies some electricity from your roof to your house during daylight hours.

I'm also personally very fond of solar thermal panels, which heat hot water. We've had a whole week of completely free 60 degree water, thanks to our solar thermal panels this past week.

@Shedbuilder so we were having work done in the rest of the house, so our builders did the prep for the UFH, and then the ASHP company fitted the piping and insulation. Our builders then screed on top not sure on the price of that as it was wrapped up into a larger quote for the build. Flooring was additional which we (well my OH) fitted himself. As per my earlier post the ASHP guys supplied and fitted the radiators/UFH.

I’m not pretending it’s cheap?!? These are actual numbers of what we paid on invoice..,

And yes the company are still in business and have been back to service since. We’re very happy with the work they completed and wouldn’t hesitate to use them again.

So clearly there were other major costs involved, but you just haven't included them - so anyone else hoping to have something similar done on their property is in for an unpleasant surprise when the bill is much higher...

@Shedbuilder
The reason I said about wishing I'd gone for solar water heating with our ASHP is that we needed to replace our tank and it appears that there is a different tank required to be linked with the panels.
I don't think I want to fork out for another tank within a year.

Can anyone recommend an ASHP engineer in The South East for servicing. I inherited an ASHP when I bought my home and am having great difficulty finding an engineer. Thanks

I think I have PM'dyou. Possibly several times

Yes, you need a solar coil if you're going to put solar thermal panels on the roof. If anyone is thinking of having an ASHP and is considering solar thermal too then best to get one that can manage both systems.

Les Lavandes, you can contact the manufacturer and ask for their recommended installer in the area, then contact them and ask if they do servicing. Is the company that installed the ASHP in business? Ask them. They should be shown on your MCS paperwork.