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Our 10 year old Grant heat pump failed

Mike Patrick · 2026-03-06T07:59:17Z

@editor A sorry coincidence but my heat pump has also just failed! You have my commiserations and I agree with all the points made in your video. The decision now is do I just replace my 10 year old Grant heat pump with their latest model, or go back to basics and review all aspects of the existing installation. Mine was a new system (not a retrofit) with UFH but has the same problems you've encountered. The installer is long gone although our local heating engineers are Grant approved installers. But I've already seen some warning signs and I'm inclined to research more widely to be sure I'm getting an installer I can rely on to know what they are doing. TBH I'm not impressed that the ASHP only has a 10 year life. Mike

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Air Source Heat Pumps (ASHPs)

Last Post by downfield 2 months ago

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 3 years ago

Posts: 4714

07/03/2026 10:38 pm

Posted by: @mike-patrick

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£280 it was better to consider a new ASHP given its age!

Well thats clearly nonsense. If a £280 pump failed in a boiler you would replace the pump, as you would in an ASHP.

Posted by: @bobflux

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These systems should work fine without requiring the user to become a part time heat engineer and plumber. Unfortunately, visits from the "tech wizards" are damn expensive, and one tends to lead to another, then another... at some point it becomes profitable to invest the time to learn just enough to debug it on your own.

You can diagnose most of the issues yourself if you have a service manual, access to installer settings, and a forum with people willing to help.

Sadly that's true of many things these days. The skill of fault diagnosis has become increasingly rare as things have become less repairable. Cars are just as bad, take a car with a fault into the workshop and basically most of the fitters (I will not dignify when with the title engineer, because mostly they aren't) will plug it into the computer and change parts until the problem goes away, charging the customer each time, without a shred of understanding.

Posted by: @mike-patrick

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Our ASHP has a history and about 5 years ago we did have a new PCB, which cost then about £800.

I had to have a new PCB on a boiler and it cost £500, its probably the most expensive part because its model specific whereas most other parts are generic. The boiler in question was very simple, I suspect a more modern boiler would have been more.

I think @bobflux has summed up the way to approach this in his post above here

This post was modified 2 months ago by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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downfield

(@downfield)

Estimable Member Member

Joined: 1 year ago

Posts: 131

09/03/2026 4:16 pm

Posted by: @editor

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If a major component fails out of warranty (for example the compressor or main PCB)

This is a bit off topic but mention of PCBs reminded me of an incident a few months back that may be of general interest.

We had a 5yo Bosch tumble dryer that failed out of warranty and the local repair guys said it needed a PCB which with installation was going to be £200+ and therefore not worth repairing. Of course they wanted to sell me a replacement, and in the end I did go for a new one this time with 5 yr warranty.

But before deciding I searched for "PCB repairs" and found this company

https://getitfixedltd.co.uk/

which does repair PCBs as well as lots of small electronic appliances. I read somewhere that they can often repair old hifi/electronic equipment that may be obsolete.

In the end I did go for new but only because the dryer was in a stack (above the washing m/c) and changing the PCB was a two-man job to get it down and opened up.

I can't see that they tackle ASHPs so this is more for general information than specific to this thread (or forum!)

Mitsubishi Zubadan 14kW with Mixergy 210l DHW in 220m2 barn property. 24 solar panels = 9kWp with GivEnergy 5.0kW Hybrid inverter and 19kWh GivE batteries. Jaga Strada fan-assisted rads throughout. Landvac vacuum glazing/triple glazed windows.

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