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Pipe sizes for ASHP

Air Source Heat Pumps (ASHPs)

Last Post by DougMLancs 3 years ago

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DougMLancs

(@dougmlancs)

Estimable Member Member

Joined: 3 years ago

Posts: 48

Topic starter 07/04/2023 7:42 am

Hi All, We’re looking at getting an ASHP for our 1960’s 3 bed semi as we’re very keen to move away from FF and we’re in the middle of having Solar PV and battery installed. The house currently has a gas combi in the kitchen with 22mm pipes going up into the ceiling void but then before the pipes exit the void into each room they’ve downsized them to 10mm pipe (presumably to make them less intrusive since they’re not hidden behind plaster). I’ve read that full microbore can affect the viability of ASHP but can these short runs of microbore be worked with or are they best being upsized? We only moved in last year and are planning on redecorating throughout and upgrading radiators at the same time so now is the time for anything messy!

Smart Tech Specialist with Octopus Energy Services (all views my own). 4.4kW PV with 9.5kWh Givenergy battery. 9kW Panasonic Aquarea L ASHP

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Mars

(@editor)

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Joined: 5 years ago

Posts: 3554

07/04/2023 8:44 am

There are varying schools of thought on microbore, so I’ll let someone else tackle that.

As for upgrading your radiators, it's definitely a good idea to do this at the same time as installing the ASHP. Radiators designed for use with fossil fuel boilers may not be the most effective option for use with an ASHP, which is what we discovered. We upgraded rads in our coldest rooms to Stelrad K3s (from K2s) and they were a game changer, even more so when running on cooler weather compensated flow temperatures. If you have the budget, I’d definitely upsize where possible.

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DougMLancs

(@dougmlancs)

Estimable Member Member

Joined: 3 years ago

Posts: 48

Topic starter 07/04/2023 9:02 am

Thanks @Mars- yes most are only K1’s or K2’s. From my own assessment via the MCS Heat/loss Heat Pump spreadsheet then there’s a few rooms that need the upgrade more than the others but we’ll try and as many as funds allow. The house has CWI but if we’re decorating anyway then we might add some internal insulation too

Smart Tech Specialist with Octopus Energy Services (all views my own). 4.4kW PV with 9.5kWh Givenergy battery. 9kW Panasonic Aquarea L ASHP

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bontwoody

(@bontwoody)

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Joined: 4 years ago

Posts: 887

07/04/2023 9:30 am

Microbore pipes can be viable, have a look at heatgeek on youtube. A good test is to turn down your combi boiler to 40 degrees for the heating and see which rooms are warm enough and those that might need the rads or pipe upgrading. My bathroom was fine on microbore but I changed most of the other rooms to 15mm and bigger rads.

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
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DougMLancs

(@dougmlancs)

Estimable Member Member

Joined: 3 years ago

Posts: 48

Topic starter 07/04/2023 12:41 pm

@bontwoody thanks- I’ll take a look and turn the flow temp down too. We only like to have the house about 18 C which it currently does fine with a 55C flow but I notice the house temp maxes out at about 20C when we try and crank it up to 22C for a visit from my in-laws.

Smart Tech Specialist with Octopus Energy Services (all views my own). 4.4kW PV with 9.5kWh Givenergy battery. 9kW Panasonic Aquarea L ASHP

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