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Pipe Work Question?

Air Source Heat Pumps (ASHPs)

Last Post by KenBone 2 years ago

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EcoBaker

(@ecobaker)

Estimable Member Member

Joined: 2 years ago

Posts: 44

Topic starter 22/03/2024 6:01 pm

I'm in that common situation where after having a heat pump installed and the performance isn't great, I've dived into youtube and forums like this only to realise that maybe my installer didn't design/install/set up the system particularly well.

I'm in a good situation that I still owe them over £600 for some of the work, which means I can hold that over them. The question I have is about the main pipe work for the flow and return from the HP unit. I have a 3.5m section in my loft that is plastic 22mm pipe, not copper like all the other pipe work. I understand that this will have reduced internal diameter and thus flow, maybe costing me efficiency. Should I hold back final payment and insist this is changed (along with a few other niggles I've found) or is it minor enough not to worry about?

(should add Samsung Gen6 8kw, on two bedroom victorian mid terrace)

This topic was modified 2 years ago by EcoBaker

Samsung Gen6 8kw ASHP in a two bed victorian mid terrace.

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bontwoody

(@bontwoody)

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Joined: 4 years ago

Posts: 953

22/03/2024 11:29 pm

I think the 22mm plastic pipe might be a bit small for 8kw. 22mm copper is considered ok for 5kW I think. This link gives more detail. https://www.heatgeek.com/does-my-pipework-need-upgrading-for-a-heat-pump-with-cheat-sheet/

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Mars

(@editor)

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Joined: 5 years ago

Posts: 3803

23/03/2024 8:08 am

The issue with the 22mm plastic piping in your loft could potentially impact the efficiency of your heat pump system, especially if it differs from the rest of your installation in terms of diameter. We have this issue where the previous owners “narrowed” the pipework when they extended the heating to the north end of the house, creating a bottleneck which I think is the major issue that the rads at the far end of the house struggle.

Did your installers run all the pipework for your system - copper and the 3.5m run in the loft?

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EcoBaker

(@ecobaker)

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Joined: 2 years ago

Posts: 44

Topic starter 23/03/2024 8:22 am

@editor Yes so the pipe work from the HP that runs externally to the loft is copper, then the pipe work runs length of loft to the other end where the DHW tank is, that section inside the loft is plastic. I need to measure accurately to check diameters, but im fairly certain that it’s the same as the copper pipes.

Thinking about it now, all l the pipe work externally from the HP is insulated, I’ve assumed it copper, but don’t know for sure, I might have to check that.

Samsung Gen6 8kw ASHP in a two bed victorian mid terrace.

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bontwoody

(@bontwoody)

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Joined: 4 years ago

Posts: 953

23/03/2024 10:43 am

There is a good video explaining the pipe sizing issue here

https://renewableheatinghub.co.uk/forums/postid/29119

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KenBone

(@kenbone)

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Joined: 2 years ago

Posts: 49

24/03/2024 9:54 pm

Posted by: @ecobaker

↑

I'm in that common situation where after having a heat pump installed and the performance isn't great, I've dived into youtube and forums like this only to realise that maybe my installer didn't design/install/set up the system particularly well.

I'm in a good situation that I still owe them over £600 for some of the work, which means I can hold that over them. The question I have is about the main pipe work for the flow and return from the HP unit. I have a 3.5m section in my loft that is plastic 22mm pipe, not copper like all the other pipe work. I understand that this will have reduced internal diameter and thus flow, maybe costing me efficiency. Should I hold back final payment and insist this is changed (along with a few other niggles I've found) or is it minor enough not to worry about?

(should add Samsung Gen6 8kw, on two bedroom victorian mid terrace)

That's too tight IMO, we would use 28mm copper, or 32mm MLCP

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