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Mixergy Tank Failure

bontwoody · 2025-09-13T05:40:14Z

Hi. I had my Mixergy tank fitted nearly three years ago and on the whole I've been very happy with it. A week or two ago we noticed a small leak on the floor beneath the piping. Initially I thought it was a leakage compression joint which I nipped up. This week I was woken by the sound of water and saw that the tank was discharging water via the tundish when heating. The most likely reason seemed to be a low charge in the expansion vessel, so I removed this and checked it. It was at 50psi. I've contacted mixergy and they suggested I reduce this to 2.5 bar and monitor the situation. It was at this point I noticed that the side of the tank seemed bulged out. When I had the tank installed the plumber pointed out to me a slight bulge in the outer case which I put down to over zealous insulating foam insertion at the time. I recontacted Mixergy and they told me to stop using the tank and they would replace it under warranty. That was Wednesday and I have heard nothing since. What I would like to know is what might have caused the problem and if it lies with the tank or the installation by the G3 plumber or the failure of a part, presumably either a valve or the expansion vessel which seems fine. Images attached. Any comments welcome. Thanks

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Mars

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06/10/2025 9:58 pm

@bontwoody you’re joking! This story gets worse and worse.

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JamesPa

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07/10/2025 6:33 am

Posted by: @editor

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@bontwoody you’re joking! This story gets worse and worse.

In fairness to mixergy several on this forum including me also said switch it off. The apparent damage was so severe there was a real risk of catastrophic failure. Not worth that risk.

However, this being the case, mixergy should have delivered a replacement tank next day!

This post was modified 3 months ago by JamesPa

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Mars

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07/10/2025 7:05 am

Posted by: @jamespa

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However, this being the case, mixergy should have delivered a replacement tank next day!

That’s exactly my point. Kit and equipment fails, but this has taken an incredibly long time to resolve given that it’s your source of hot water (and it’s still not resolved).

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bontwoody

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Topic starter 07/10/2025 8:07 am

@editor The latest is that I phoned the plumbing company yesterday to see when they are coming back and they said they they have sent a quote including the list of parts and are waiting for them to authorise it. I emailed Mixergy to ask them to expedite it. No reply yet.

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Toodles

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07/10/2025 8:29 am

@bontwoody I rather feel that this drawn out episode is not going to do Mixergy’s reputation much good at all! Toodles.

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Mars

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07/10/2025 12:59 pm

@bontwoody how long has it been now since you started the process to get it replaced?

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bontwoody

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Topic starter 09/10/2025 11:17 am

@editor @mixergy

This is now 4 weeks without a hot water cylinder.

I currently have a non-functioning cylinder in the cupboard and functioning but non installed one in the hall.

I am currently being bounced between the installer, who are waiting for Mixergy to approve the installation quote and Mixergy who say they are dealing with it since Monday!

Ive got to say this isnt the service level I was expecting in what is really an urgent situation.

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Mars

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09/10/2025 12:14 pm

@bontwoody, I have to say, the response time here is really concerning. This is your hot water we’re talking about, not a minor issue. Most installers will warn that heating might be off for a few days during works, but leaving someone without hot water for this long is unacceptable.

@mixergy, please could you respond and explain what’s going on here?

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ASHP-BOBBA

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09/10/2025 9:05 pm

OH my just read all of this, so you are still waiting?

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bontwoody

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Topic starter 09/10/2025 9:18 pm

@ashp-bobba Yes unfortunately 😔 I just read your other thread but my issue isn't quite the same as I was using the immersion on cheap rate and not the heat pump to heat the cylinder. Not nearly as interesting 😁