Heat recovery systems

Majordennisbloodnok · 2022-01-14T14:18:43Z

I know we've spoken a lot on this forum about various types of energy generation technologies and heating systems However, in the interests of maximising the efficiency of any energy generated I'm rather interested whether anyone has any experience of heat recovery systems. I have found a little information about systems being installed into new builds but given I have a house already I'm particularly interested in any retrofit solutions and how cost effective they might be. In short, are they any good and are they worth considering?

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robl

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25/03/2022 4:29 pm

We had a vent axia HR25 for a few years, it worked quite well. It's a fan replacement unit, with heat exchanger - there are quite a lot on the market these days. It measures humidity and runs faster after a shower typically.

In our case it was a "gateway" unit, and I sold it on after a few years 2nd hand. We did a lot of air-tightening, and fitted full house MVHR which does the same thing, just better. I agree that the money is difficult to justify - I think it saves around 1MWh of heating per year in our 4 bed 120m^2, 300m^3 house, which equates to around £80 of gas these days, while using £20 of elec. As it was a diy fit, that gives a payback of £2400/(£80-£20) = 40 years. If it were pro fitted, the bill would be 2*. But the house is so much nicer now, we don't have to mess around opening windows when it gets stuffy, it's quiet inside, we're saving energy hence CO2. We got a new kitchen 15 years ago, that will never pay back...

*edit - added in the elec cost to the "payback" calc

This post was modified 3 years ago by robl

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heat-pump-newbie

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16/04/2022 11:44 am

@robl What make of MVHR did you get please ? Do you expel kitchen air separately (I've seen this mentioned as an option as it might clog filters in the MVHR unit sooner)?

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robl

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16/04/2022 12:38 pm

@heat-pump-newbie

We have a Vent Axia Sentinel Kinetic Plus BH. Which I recommend, had it maybe 8 years, never gone wrong. It has a kitchen extract, and I put a grease filter on it. We independently have a hob top extractor fan, which goes outside directly. I agree with your comment - if you do a lot of frying there will be a lot of grease, and best not to clog up the mvhr with it. So once every few days the extractor is on for 10 mins.

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