@iaack Thanks all for your insights - its really much appreciated. Ideally I would have heard from someone that had first hand experience of having their GSHP compressor replaced but I guess these people are relatively few and far between. Anyway, to round this out, the total quote for my repair is £3.5K - the new compressor was £1730, labour/travel £1330 and the rest in sundries. Labour rates charged at £60ph. My purpose here is not to complain about the cost - it is what it is and I have no choice. Rather, its to flag to others the reality of potential repair bills that could be around the corner. Lets just say it was a v unpleasant surprise!

My bigger concern is that the new compressor and repair work is only warranted for 12 months - in theory I will have the same risk exposure this time next year with no means to warrant or insure. That doesnt make we sleep well at night when the only other option is a completely new pump (>£10K). Indeed, I was trying to think of anything else in my life where I could wake up one day to such a pressing, costly bill that I couldnt otherwise have warranted or insured???  @transarent raised a good point about long term warranties or inclusive service cover which I wish I had the option to buy into.   

Thanks again 

The guarantee on a compressor is surely worth more than the £3.5k repair quotation?!

If you can't get a reasonable guarantee for having the manufacturer-approved part fitted, then you might as well buy a really cheap GSHP elsewhere and expect to replace it every 4-5 years!

I realise that these are not like-for-like comparisons, however

1: Here's a company in Poland who manufacture GSHPs and sell on ebay at £1900, so long as you arrange collection.

2: Also from ebay, here's a brand new Dimplex GSHP being offered at £1500; pickup from Swindon

3: I can import a 10.5kW GSHP from China via AliExpress for £5558  plus £1338 carriage:

Or do 2 minutes extra detective work and buy the identical model direct from the Chinese manufacturer on Alibaba for £1379 + carriage (negotiable)

And it doesn't take me too long online to find several workshops that refurbish scroll compressors (usually in the Midlands).
They'll sell you one for £300, and arrange to come to site and fit it if you pay cash! 🤔 

Sure, none of those options have a warranty of any useful value...
... but there's a better than even chance that they'll last longer than the 12month warranty you get by using an 'official route'.

@delt wow!  How old is the system?  This is why I took out the 10 year fixed price service and warranty on my Daikin ASHP. To cover such eventualities. 
Best wishes with your fix

Hello Julian, having recently purchased a Daikin ASHP, I wish to do the same and filled in the on-line application to Daikin to know about all the options (likewise, I wish to have ten years of coverage that is worry free) as yet, Daikin have not replied and I even asked my installers who contacted the local rep and he/she has not been in touch yet either! How did you organise your contract please? Regards, Toodles.

@toodles have you created an Daikin Stand by me account?  This should show your products and warranty details. 
Your installer should register your installation with Daikin. And then you build your service from there. 
Also you can call the UK help desk

@julianc Thank you Julian, I’ll try again and see if the Stand by Me site will accept my application; I do recall going through such a procedure but saw various error messages at the time so maybe the system has not registered my application at all. Regards, Toodles.

@toodles by the way, their Standbyme website seems to be down at the moment which I have reported to Daikin

Thank you, even when the site is not ‘down’ I don’t think it is functioning properly as the first question I am asked when opening the site from my Daikin Service, Register Now, the app asks ‘To get started, please select the type of indoor unit you have in this installation.’ I have a monobloc without any indoor unit so can go no further! Regards, Toodles.

@toodles Your installer has to give you a Daikin commissioning code.  It was 5 letters & numbers. You use this to register with Standbyme and it links to your specific products and serial numbers.

Thank you Julian; I’ll look amongst my documents for this and follow it up via that route. Regards, Toodles.

I have now looked out that document and tried again but with no luck as it tells me it doesn’t recognise my commissioning code (and now I remember trying this in the early days and it didn’t want to work then, so I have contacted my installer… Regards, Toodles.

@julianc Hi Julian - the unit is 12 years old. I believe its a Copeland scroll compressor within, which from a quick google, has an expected lifespan of 12-15 years. Im trying to be philosophical about the bill, and if my GSHP lasts for another 12 before it needs replacing then I guess its in line with expectation. What seems odd is to have such a critical and expensive component with a proposed long life span but only a 1 year manufacturers warranty? I have asked the GSHP installer if they would be willing to provide extended cover for the new compressor if I paid but they declined. We will all have our ongoing discussions re relative running costs of heat pumps vs conventional boilers but if the initial purchase + repair/maintenance costs are so high across the unit lifetime then these are weighty factors in any economic argument. Obviously my £3.5K would have gone much of the way to buying a brand new oil or gas boiler if I was so inclined.