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No spare parts for Vaillant Ground Source Heat Pumps in the UK & major corrosion issue is another problem for GSHP

phowardstutterheim · 2023-01-16T14:33:11Z

We've been without any heat since 28 December, as our 7-year-old Vaillant Geotherm 17kW ground source heat pump gave out due to internal corrosion. This corrosion can cause major internal damage - possibly to the condenser (£3000+), as well as to the backup heater and several sensors. The GSHP and all UFH pipes fill with black crud and particles, as though they were choked with ash. To avoid this corrosion, which comes from several sources that are part and parcel of heating systems (e.g. UFH pipes, mains water, etc.), we are forced to install an expensive (>£1000) filtration system, as well as pay for repair of all damages. We also discovered that Vaillant does NOT ensure the supply of spare parts in the UK in anything like a timely fashion. Vaillant sells spares through distributors and, for most spare parts, distributors must order the spares - all say that delivery takes 7-10 working days. However, we learned that these distributors actually order from Vaillant UK, which turns around and orders these from Vaillant Germany. The spares we ordered on 28 December from Direct Heating Supplies online were NOT delivered in 7-10 days - instead, Direct Heating told us after the parts hadn't arrived that the supplier didn't have the spares and that they had to re-order, which would take another 7-10 days. I then called Vaillant's Heat Pump Division, who told me that the only way I could get the spares needed was if they had them in stock AND their own engineers performed the repairs. We were thus forced to use Vaillant engineers, which cost at least twice as much as our local GSHP service team - parts also cost more when purchased direcly through Vaillant. When the Vaillant engineer arrived six days later, he didn't have two of the spares that are needed - and couldn't say when these would be available, as Vaillant has to order them from Germany. This situation is reprehensible. LESSON 1: Installing a Vaillant GSHP requires an act of faith that may leave you confronting a real emergency that cannot be addressed because the manufacturer is unwilling to provide the critical spare parts required. Not only are two families living with 12C internal temperatures - and using an electric boiler for hot water and space heaters to keep minimally warm - hoping that the temperatures don't drop further; we are not insured for GSHP emergencies (NFU excludes these) and will only be insured in the case that our pipes freeze and burst, causing major property damage. LESSON 2: You must consider installing a magnetic filtration system anytime you install a GSHP - you are very likely not being advised that this may be essential if you want to avoid major damage to your GSHP within a few years after installation. Be prepared to add a further £1000-£1500 to your overall installation costs - if you download the Elyasator SorBox manual on this website you can read all about the causes and solutions:If you have similar experiences please post them here.

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Ground Source Heat Pump (GSHPs)

Last Post by phowardstutterheim 6 months ago

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phowardstutterheim

(@phowardstutterheim)

Trusted Member Member

Joined: 4 years ago

Posts: 42

Topic starter 18/03/2026 9:46 am

Indeed, I might have done what you suggest had I not had to both preserve samples for a legal case and provide court-worthy evidence of the contents. Legal proceedings are expensive and I wasn't doing this simply for my own satisfaction.

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bobflux

(@bobflux)

Reputable Member Member

Joined: 7 months ago

Posts: 171

18/03/2026 2:43 pm

Posted by: @phowardstutterheim

↑
In your comment, you are both confident and rude

Yup.

As an engineer, perhaps the most important part of my job is to put my foot in it. Toxic positivity is deadly.

You have a situation that is, in theory, impossible. Yet it is happening. Cheer up, that's how discoveries are made! Thus you have two options. a) Do nothing. b) Get data and figure it out, get some closure for the issue that haunts you, you'll feel better about it, guaranteed lol

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phowardstutterheim

(@phowardstutterheim)

Trusted Member Member

Joined: 4 years ago

Posts: 42

Topic starter 18/03/2026 6:37 pm

Well, that sounds better. However, we are no longer dealing with this. The GSHP is still working, and we don't have the resources to pay experts who, at the end of the day, are asking us to tear apart the entire system and subject everything to laboratory analysis.

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