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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JamesPa

(@jamespa)

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03/10/2025 9:59 pm

Posted by: @bontwoody

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Posted by: @bontwoody

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So after waiting over 3 weeks for a replacement cylinder, it arrived yesterday and the installer arrived this morning. Unfortunately he didnt know what the job was prior to getting here and didnt have the required fittings so will have to come back (3 hour drive from Brecon).

The amount of times this happens is staggering. Driving across the country to do a job and not fully briefed or prepared. Was this an installer from Mixergy or someone that was assigned to you? Truly staggering.

Sorry to say this but the is NOT in any way special to the plumbing industry.

I saw this all the time when I was working full time, and still do. For example we had five visits from different Openreach engineers to make a single copper telephone connection to a refurbished building. On no occasion did the engineer who turned up know what he was supposed to do or any of the history of what previous engineers had discovered. So each engineer was surprised to discover what was there or even what the job was and went away without completing the job. In the end we made a decision what route the cable was going to take, fully prepared it for them, and then made sure we were ready to show them where the connection points were both at our end and to the live network at 'their' end. All they had to do was pull a cable through a duct, fit an NTU and punch the other end down onto a couple of IDC terminals. Yet amazingly one engineer turned up with insufficient length of cable because, (or so he claimed), theft of copper is so rife that the Openreach engineers carry only the exact amount of copper cable allocated to the job! About 9 months later we finally got our telephone connection!

One exception was UKPN who seem, at least in my experience, to have a joined up team, which is perhaps why several of the people I encountered told me how much they enjoyed working for the company. But that appeared to be an exception to prove a rule.

Long ago I adopted the defensive tactic of assuming that whoever turns up for whatever the job is wont have a scooby what they are supposed to do and quite possibly wont have the tools. This means that I make it my business to know what is going on, what needs to be done, why, and to the extent I can, how to do it. You may say that this should be unnecessary, and it should, but the fact it that it isn't! Resistance in this case is useless!

This post was modified 3 hours 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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