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The Reality Behind a Failed Heat Pump Installation – and an IWA Insurance Rejection

Ian · 2026-04-08T14:10:44Z

We are an unremarkable couple in our 60s, living in a 1900 three-bedroom terraced house in South Manchester. In 2022, after receiving a small inheritance from our parents, we decided to take the plunge and invest in a new central heating system to replace our temperamental 30-year-old boiler. After much research and deliberation, we decided to ‘do the right thing’ environmentally and invest in an air source heat pump. The environmental credentials were appealing (roughly four units of electricity generated for every unit consumed), as was the government’s support in the form of a BUS (Boiler Upgrade Scheme) grant which, at the time, was £5,000. We would also be able to get rid of the gas supply completely and save additional costs by not having to pay the monthly gas standing charge. We didn’t know of anyone else who had installed an ASHP, so we were in unfamiliar territory and learning one step at a time. There were so many acronyms to come to terms with (EPC, MCS, NAPIT, BTU values, BUS grants, CWI…). It was complicated and confusing, and we felt quite overwhelmed and lacking in confidence. It would have been so helpful to have had some independent, easy-to-understand overview of the process... a metaphorical 'holding of our hand' through it all. We didn’t know where to look. Advice seemed patchy and far too technical for us newbies to understand. We were both working full time, still supporting adult children, having building work done and had very little spare time to deep dive into the world of heat pumps. But we took it one step at a time, researched as much as we could, and kept asking lots of questions. The first step was to find an ASHP installer. We knew from online research that it was important for the installer to be MCS registered. We contacted ten installers based in and around Manchester, all of whom were MCS registered. After asking some basic questions as part of the initial enquiry, we shortlisted these down to five. We invited them to come and look at our property with a view to providing advice, a quote and a recommendation for which model of ASHP they thought would best suit our home. From the quotations received, we chose RA Renewable Solutions. We discussed the pros and cons of different ASHP models and settled on the 11kW Vaillant aroTherm. They were also happy to install underfloor heating in the kitchen as part of the installation, which some installers were not willing to do. To qualify for a BUS grant, we had to commission an EPC (Energy Performance Certificate) assessment and implement any recommendations, particularly in terms of insulation. The assessment recommended cavity wall insulation (CWI). However, because of the age of the house (1900), our walls only had finger cavities which were too narrow to accommodate regular insulation. This all had to be proved and documented. Firstly, we had to commission a chartered surveyor to inspect our walls. He asked us to commission a CWI installer to inspect the walls with a borescope and send him the photos, which we did. Three reports later (and a rapidly depleting budget), we were finally able to complete a ‘Cavity Wall Insulation Exemption Form’. Instead of CWI, we committed to removing the existing plaster on the two external walls (front and back) and replacing it with new thermally insulated plasterboard, which would have the same effect. With this in place, we were finally eligible for the Government’s BUS grant. The next step was to buy radiators so that the builders knew where to put the pipe centres when installing the plumbing first fix. The ASHP installer commissioned an assessment of the BTU values required for each room. This came to us in the form of a rather blurry, difficult-to-read WhatsApp screenshot, rather than the detailed report we were expecting. However, we took it along to a radiator retailer and asked them to interpret the values for us so that we could properly size the radiators. Radiators were ordered and pipe centres marked on the plans. An ASHP system needs a large water tank. We had originally specified a Vaillant uniTower hot water cylinder. However, after discussions on site, the installer suggested we change this to a horizontal hot water cylinder, which would fit under the eaves in the loft and be a better use of space. We emailed the installer to ask if the new cylinder (Joule) was compatible with a Vaillant ASHP system and whether it had a warranty comparable to the Vaillant uniTower. We received a reply confirming that the Joule cylinder was compatible with our ASHP system and had a 25-year guarantee. There were some delays to the building work. Some were the fault of the builder (subcontracted suppliers were not organised in a timely manner). Others were caused by unforeseen structural issues. After removing the old plaster to replace it with thermally insulated plasterboard, it was discovered that the front elevation of the house was structurally unsound and had to be rebuilt. We provided the...

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 3 years ago

Posts: 4979

05/06/2026 7:16 pm

Firstly I am delighted you have won this one and congratulations on your persistence. There is no question that this is a major victory. Well done to you and everyone involved.

That said I confess that, before you did, I doubted you would succeed. My doubt was based on the wording of my own insurance contract which, frankly, is not worth the paper it is written on.

My question therefore is, did they admit that they were wrong, or did they just change their mind without admitting fault. The significance of this question is that, in the latter case, it might well be a cynical attempt to minimise poor publicity without any long term effect, whereas the former case is a real change of position.

I share your concerns about structural failing, which is why I cynically suspect it might be more about avoiding bad publicity rather than about a real change of heart.

Hopefully you can tell us and hopefully my cynicism is misplaced.

This post was modified 1 hour ago 2 times 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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