Pipe sizes for ASHP
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
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.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
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
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/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60
@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
- 22 Forums
- 2,036 Topics
- 44.4 K Posts
- 17 Online
- 3,239 Members
Join Us!
Trusted Installers
Struggling to find a reliable heat pump installer? A poor installation can lead to inefficiencies and high running costs. We now connect homeowners with top-rated installers who deliver quality work and excellent service.
✅ Verified, trusted & experienced installers
✅ Nationwide coverage expanding
✅ Special offers available
Latest Posts
-
RE: The Rise and Fall of Europe’s Most Generous Green Subsidy
@dwynwen welcome back… and glad to hear you made it thr...
By Mars , 7 hours ago
-
RE: Air Source Heat Pump - Side Alley Suitability
@ad3628 I’ve seen loads of heat pumps successfully inst...
By Mars , 7 hours ago
-
RE: Hitachi Yutaki SCombi Heat Pump - Thermal Off's
@trebor12345 The Auto function is supposed to adapt au...
By Heatgeek , 9 hours ago
-
RE: In the middle of an ASHP installation - a few questions (and issues)
@jamespa they didn't provide any contract, or design pr...
By benson , 12 hours ago
-
RE: The Great British Heat Pump Quiz
@allyfish thanks for the feedback and glad it was fun! ...
By Mars , 14 hours ago
-
RE: help sizing rads based on room by room heat loss
If its 1988W at DT 50, which is how most radiators are ...
By JamesPa , 19 hours ago
-
RE: Career change – entering the world of heating and heat pumps
@editor Mars, thank you. That's along the routes I was ...
By Lakey , 19 hours ago
-
@editor thanks Mars, it's a rare occasion I'm looking f...
By big_si , 1 day ago
-
RE: Efficiency Concerns on newly installed Mitsubishi Ecodan 8.5kW
@ashp-bobba and @jamespa - thank you both for all your ...
By CBrenewable , 1 day ago
-
-
Win one of five "Heat Pumps 101" Courses
Heat pumps are gaining traction in the UK, but between ...
By Mars , 2 days ago
-
RE: Agile: average import cost vs other tariffs?
@toodles thanks for the analysis. I'll be really intere...
By Old_Scientist , 2 days ago
-
RE: ASHP Ecodan L9 error - No Heating but Hot Water
@phoenix15 I'm no plumber so please don't take this as ...
By dnagre , 2 days ago
-
RE: Is this normal? Click of the DHW returning to space heating
@grantmethestrength Oh sorry to hear that, there should...
By ASHP-BOBBA , 2 days ago
-
@ashp-bobba TBH the ladies are rather disorganised, so ...
By Cathyem1 , 2 days ago
-
RE: Solar Power Output – Let’s Compare Generation Figures
And for those of us without an automatic irrigation sys...
By Majordennisbloodnok , 3 days ago
-
Logically, the lower frequency = more gentle, yes, but ...
By SUNandAIR , 3 days ago
-
RE: Ideal Logic ASHP - change from 55°C to 35°C Heating?
Good point. I’ll keep my eye on the manifold temperatur...
By Tomdad , 3 days ago
-
RE: How hard and expensive would it be to change panel and add battery?
@transparent It is a setting that Octopus make via the ...
By Toodles , 3 days ago