That's great and in principle I wouldn't disagree, but if someone is being quoted 18K to fix a heating system then I can fully understand their reluctance (and surely you can also) - that's just silly money, particularly as the part that is actually faulty probably costs no more than £500.

Had a couple of quotes for a replacement £16-18k.

Considering having it removed and going oil, unfortunately gas not an option.

What's to stop you simply replacing the heating bit with an ashp.  Presumably all the emutters etc are fine so it's just a straight swap of heat source which shouldn't cost anything like 16k and is more maintainable.  

It's a bit disappointing that gshps haven't really caught on, but I guess that the upfront cost for the coil makes them less attractive and thus reduced production quantity leading to higher cost.

No one seems to know anything about it, I'm over £500 down just having 3 separate 'expert' heating engineers stand there and let me shown them how it works and them to scratch their heads and walk away and send me a bill. On top of this it took me a while just to get someone to come and look at it, we had no heating in November.

Is there anyone out there that can help?

The main issue seems to be a HTF alarm (GT8/GT9) and then a HTF max which trips the unit out. I'm told there should be a particulate filter but cannot find it, I know it's not in the inside of this model, so it might never have been fitted.

I increased the alarm threshold and lowered the water temperature to force the pump to drop into rad heat in order to get heating into the house. This was in November, and it's limped through to now, but the GT8 temp has increased to over 70 with a GT9 at sub 30, and with water temperature of only 40. Now cannot get it to jump to rad heat. If I try add heat to get it to cycle the water temp to over 60, then a electrical cassette alarm triggers.

Alto Energy have been quite helpful and have told me to drain the system and check the flexible hoses below the electrical cassette, but this is beyond my abilities and when I have suggested this to the heating engineers, then don't seem keen either?

I have been given a quote to install a Worcester Bosch gas boiler and HW tank, it's quite eye watering after spending £25k on a system I thought we would get 20-30 years out of, however, it's a lot cheaper than a replacement GSHP.

Its a fact that there are more engineers out their that understand gas boilers, and very few that are either interested or have knowledge of heat pumps. 

On top of this the increase in electricity/kWhr has really also enforced my belief that we are just not ready to heat our homes with this technology.

Had a couple of quotes for a replacement £16-18k.

Considering having it removed and going oil, unfortunately gas not an option.

I've also managed to get mine fixed too.    A heat pump engineer came out and isolated the issue to the control box and put me in contact with Alto Energy who seem to have bought up a large stock of IVT parts. 

An Alto Engineer came out and it's the first time I've spoken to anyone with specific IVT in depth knowledge rather than a general heat pump background and it's made me more confident in keeping the GSHP in and working now I know there is expertise and parts available. 

He also mentioned the issue with the flexible hoses and as @greenlight mentioned in his video it's important to add inhibitor as part of a regular maintenance routine which I wasn't aware of before.     

I had a quick look at costs for replacing with a new GSHP or 9KW Air Source and both extremely expensive even though the ground work has already been done.  the cost of buying the kit alone comes to around 10K or 6k including water tank so hoping to keep this running for a good few years longer.    

Sweetest of all my friendly pumper only charged me 1/2 a days labour at £150. So why do so called renewable heating experts expect you to pay over a £1,000 plus VAT?

Somebody has to pay for their ignorance!

In fairness there are some very good ones out there, as well as some poor ones.  That's true of much of the building trade, it's not special to heat pumps at least based on my own experience.  Don't forget that many, possibly most, of us have been paying about 10% more for our heating than we needed to for about the past 20 years, and 'enjoying' a reduced level of comfort, courtesy of the (gas) heating industry.