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Big Changes Coming to Our Heat Pump System

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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(@transparent)

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18/09/2025 4:51 pm

Posted by: @grahamf

↑

I am wondering why installers have concluded that buffer tanks are necessary for heat pump systems.

1: Because, deep inside, they realise that the MCS guidance has got them installing HP's which are actually over-sized.
The buffer tank throws away heat, thereby allowing the return water to be at a low-enough temperature.

2: Because it's a profitable mistake to make.
Needlessly installing a buffer tank is pretty simple, but adds to the profits.

Save energy... recycle electrons!

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JamesPa

(@jamespa)

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18/09/2025 5:04 pm

Posted by: @ashp-bobba

↑

@jamespa Oh big question ...

I just wanted to see if we could profile 1 good installation 🙂 Glass 5% full rather than 95% empty (positive approach)

We could I'm sure, but it will be drowned out by the noise from the poor systems (which may well be a minority for all we know) because the latter is amplified to satisfy the interests of big oil and now two of our political parties to do so, and they control most of the media.

The media being what it is and controlled by those it is controlled by, it matters not a jot of 95% of installations go well. What matters is that a fair number don't.

Frankly I fear that I the battle is being lost!

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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