Repiping and Reconfiguring our Heat Pump System Including Removing the Buffer Tank

Mars · 2025-09-14T09:39:26Z

After years of living with an underperforming system and much deliberation on our part, we’ve finally decided to take up Brendon’s (@heacol) long-standing offer to come and help improve it. He’s been incredibly generous with his time and advice over the years, and now he’ll be spending a few days with us to properly diagnose what’s wrong and make the necessary changes. Our goal is to significantly improve our system’s efficiency, and we’ll be documenting the entire process here on the forums and in a series of YouTube videos. The idea is to show, warts and all, why our system has been underperforming, and what Brendon does to put it right. I think it’ll be a fascinating case study, and hopefully useful for other homeowners who find themselves in similar situations. Here’s what we already know is on the cards: The buffer tank will almost certainly be bypassed (though it may get repurposed as a volumiser... we’ll see what Brendon decides). The army of circulation pumps we currently have will be cut down to something far more sensible. FRVs will be fitted to all radiators to allow proper balancing across the system. The whole system will get a much-needed flush too. The other big area of focus is zoning. Our system has multiple zones controlled by on/off thermostats dotted around the house. I’m very curious to see how Brendon approaches this, what he suggests and how it all works in practice once the changes are made. As a point of reference and context, our lifetime SCOP is 2.7, and we're hoping that the work carried will hopefully improve running costs, but more importantly, that we can deliver uniform heat around the property, where we currently have a lot of rooms that struggle to get to temperature. For us the acid test will be our TV room, the most challenging room in the house. If Brendon can get that rad up to temperature with consistent flow, I’ll consider it a huge win. Brendon will be with us for several days, so if you have any questions you’d like me to put to him while he’s here, please post them below. I’ll do my best to address them in follow-up posts or in the YouTube videos we publish.

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Air Source Heat Pumps (ASHPs)

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JamesPa

(@jamespa)

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20/09/2025 9:53 am

Posted by: @editor

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But if we’re serious about heat pumps scaling to 600,000 installs a year,

1.5M needs to be the target, being the number of gas boilers fitted each year.

Posted by: @editor

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And then there’s the installer landscape: plenty of very good and even great engineers out there, but also many who believe they’re good when, in practice, their installs are poor (classic Dunning–Kruger effect). The problem is the system doesn’t filter those out and homeowners are left to pick up the pieces

Well said. There appears to be no mechanism to filter out the duffers, not even free market competition because mcs so effeclively protects installers at the expense of consumers

Posted by: @editor

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we need to stop pretending the framework is working.

The problem I perceive is motivation to do this. Installers, even the good ones, are happy because their order books are full. The industry guardians, MCS are the problem not the solution. Government probably doesn't know, if it does know is unlikely to understand, and even if it did understand would have to fight the 'experts' in the industry to change anything, so is unlikely to succeed. Finally the oil industry is over the moon. The heat pump manufacturers probably have most to lose in the long term, but are pretty remote. How is this going to change?

This post was modified 1 hour ago 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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Transparent

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20/09/2025 10:52 am

Posted by: @editor

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Every circulation pump removed and replaced with a prototype delta-T modulating pump

Can we have a photo of that please?

And a link to an online specification would be nice too 😍

Posted by: @jamespa

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There appears to be no mechanism to filter out the duffers

The manufacturers must be pretty frustrated with the poor quality of installation.

When there's a need for so many installers, it's difficult to terminate those who aren't up to the job.

In the end, it's the execution which matters.

Posted by: @jamespa

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Government probably doesn't know, if it does know is unlikely to understand

But we should at least try to make our MPs aware.

This is a classic scenario when you need an effective Opposition.

I also take up many opportunities to raise the issue of poor installations by responding to relevant Government Consultations,
and 'Calls for Evidence' by the Commons Select Committee. It's their role to challenge departmental policy.

Both of the above receive very few 'reports' or submissions from ordinary members of the public.
When we do bother to say something, it's usually very welcome.

This post was modified 16 minutes ago by Transparent

Save energy... recycle electrons!

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