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My DIY Heat Pump installation

Polar bear · 2025-11-03T16:35:32Z

Hi All New to the forum. I did post earlier in the year saying I was going to post the details of my DIY Heat pump installation but its been a busy year and not had time to do it. All finished now and so here goes. The background 5 bedded detached house, the oldest part built in the early 1800's with various extensions over the years, was initially 2 cottages converted in to one house in the 70's. The last extension was by us of a big kitchen diner in 2010. Locality is South Lancashire, walls are mainly solid in older part through to insulated cavity in the new extension. I have insulated as much as I can and double glazing fitted about 10 years ago. Complicated heating as mostly done in the 70's, essentially the left hand side of the house (LHS) (was one of the cottages) is radiators all fed from a manifold terminating in 10mm microbore to the rads, right hand side (RHS) is similar to rads. New extension is UFH downstairs and radiators off a manifold fed by 15mm pipe. I replaced all the old radiators with type 22 about 5 years ago. House was heated by oil when we moved in but at the time of the extension in 2010 I decided that oil was bad and going to get expensive so decided down the route of ASHP then. Very little info about then so decided along with my plumber/electrician to DIY then. Got 2 ASHP one 8.3KW and the other 11.3KW off the internet for about £ 1,500 each. The initial set up was the 8.3 unit was to do the hot water (DHW) and the 11.3 the heating. After a short while it was obvious that the 11.3 was struggling so on contacting the seller he suggested linking the two via a LLH and having zone valves controlled by thermostats and separate pumps to LHS, RHS, UFH and DHW. So this is what we did and it worked.....sort of. Over the years the house was kept warmish and the DHW was OK and topped up by immersion as necessary. It started getting expensive however and with the price of electric going up, very expensive. I also realised that the ASHP were nearly 15 years old now and not as efficient as they had been so all in all needed upgrading. Looking at various links I was loathe to start spending tens of thousands of pounds on a new system and didn't want to go down the route of MCS with all the hassle. It is an old house and I didn't want people who I realised may be didn't know what they were doing coming and giving me bad advice. So, I decided to do it myself, everything was there, it maybe just needed tweaking. I was lucky as I know an ASHP engineer who gave me some advice and my wife's cousin is a plumber who is now specialising in refits of botched ASHP installations, he also gave me advice. Jan 2025 I was researching ASHP on the internet and getting quite shocked as to how much they cost, my old system came to a total of 19.6KW and I did a rough heat loss calculation off the internet and reckoned a 16KW system would do me. Other friends who had similar size houses and had spent £15K on installs had similar size models so it looked OK. As you can see all of this is generally 'back of an envelope' type stuff. Then I found on ebay a brand new 16KW ASHP for £ 850! Far too good to be true and so the old adage of if it's too good to be true...... But I researched the company and got in contact, turned out they were a heating company in Wigan who's former CEO had bought 20x 16KW ASHP and 20x 9KW ASHP from China with a view to fitting them in to peoples homes. Trouble was he then realised he would have to send his engineers to China to get trained in how to fit them properly and this wouldn't be cost effective, so he was stuck with 40 ASHP. This is maybe when he became the former CEO. So I googled the ASHP, got in contact with my contacts and looked in to it. Downside was bought as seen, no warranty and no real advice as to how to fit them. But I thought for £ 850 I could take the gamble so I trundled over there with my trailer and a very nice lady driver in a fork lift truck plonked a brand new, unopened 16KW ASHP in and I bought it. Foshan AIROSD 16KW DC abd EVI inverter ASHP, Monobloc unit with R32 refrigerant. When the heating season was over I disconnected all the old plumbing and placed the unit in a new position outside, my electrician came and connected it but this was very straightforward as all the old wiring and controls were there from the previous ASHP. After reading lots of blogs and forums such as this one I decided on the following set up. No LLH, all run as an open loop system, the LLH is still there in the return pipe but plumbed as a 2 way LLH and is essentially a dirt and air seperator in the return pipe. All zone valves taken out for LHS, RHS and UFH. All room thermostats disconnected I still have the seperate pumps for LHS, RHS and UFH, so now a Salus pump set on highest constant pressure curve feeds 28mm pipe to three sperate zones, LHS with additional pump set at velocity 1, RHS with pump set at velocity 1 and UFH with pump set at velocity 1. I was...

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Air Source Heat Pumps (ASHPs)

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Majordennisbloodnok

(@majordennisbloodnok)

Famed Member Moderator

Joined: 4 years ago

Posts: 1206

10/11/2025 8:16 pm

Posted by: @batpred

↑

Our setup does not include a heatpump, but @majordennisbloodnok has lots of experience in controlling this type of devices.

In fact, whilst I do have experience getting things talking to other things (IT background and certainly enough knowledge and sense to avoid any claim of “genius”), I don’t do a great deal of actual controlling of my heat pump. There are plenty of others here much better able to advise on weather compensation settings.

However, in order for them to have a fighting chance, some screenshots of the device now set up in the app would be good. @polar-bear, your phone should have an on/off button on the right hand side and volume up/down buttons on the left hand side. If you press the on/off button and the volume up button at the same time, you’ll take a screenshot of whatever’s on your phone’s screen at the time. If you can take screenshots of all the bits of heat pump info and settings you think might be relevant in the app, then upload those screenshots here we collectively should be able to decypher the important stuff.

A word of caution, though; do take a good look at each of the screenshots and check it for personal info before uploading. If any screenshots show your name, email, phone number, location etc., don’t upload them, or at least not until you or your wife have done a bit of photo editing to blur out that info.

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"

👍

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Grantmethestrength

(@grantmethestrength)

Reputable Member Member

Joined: 10 months ago

Posts: 174

10/11/2025 8:21 pm

Also if you have a copy of the manual it would be useful to see it. The ones I have seen are really badly written and make no sense lol!

Kind Regards
Si
——————————————————————————
Grant Aerona3 13kW
13 x 435w + 13x 480w Solar Panels
Sigenergy 10kW Inverter
16kW Sigenstor battery

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Polar bear

(@polar-bear)

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Joined: 11 months ago

Posts: 21

Topic starter 10/11/2025 10:10 pm

Attached photos of the pages that come up on the app

Also if you google AIROSD manual the next page comes up and this download is the manual that I have

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Majordennisbloodnok

(@majordennisbloodnok)

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Joined: 4 years ago

Posts: 1206

10/11/2025 10:17 pm

…and I’m assuming the “more” option on the right of the menu at the bottom of the second picture is the option that prompted you for a password?

This post was modified 4 weeks ago by Majordennisbloodnok

"Semper in excretia; sumus solum profundum variat"

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Polar bear

(@polar-bear)

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Joined: 11 months ago

Posts: 21

Topic starter 11/11/2025 5:32 pm

@majordennisbloodnok

The 'more' button takes me to

Setting/schedule/advance/version

It is the Advance that takes me to a password page....that's when I panic!

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Polar bear

(@polar-bear)

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Joined: 11 months ago

Posts: 21

Topic starter 05/12/2025 3:34 pm

Right, I have had my first full month stats in. It is all a bit 'finger in the wind' stuff. I have averaged my normal monthly electric use (when the ASHP was not running) and taken this months reading and simply subtracted the two to get a rough guestimate of how much the ASHP is using.

To recap

Victorian cottage with mixed levels of insulation, 212 square metres.

5 bedroom, 4 reception rooms with mix of type 22 radiators and UFH

Open loop system, no buffer or LLH, ASHP is running 24/7, flow rate is approx 35C.

November -3.9C lowest temp and 17.5C highest temp.

908KW total / 30.3KW per day/ 1.26KW per hour

House temp is 20.2C and 41.5% humidity

So all in all I am very happy with this, more importantly the wife is happy and finds the house much warmer and more comfortable.

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bontwoody

(@bontwoody)

Noble Member Contributor

Joined: 4 years ago

Posts: 953

05/12/2025 3:51 pm

@polar-bear I see you have the most important metric firmly in mind 😁

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

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dgclimatecontrol

(@dgclimatecontrol)

Estimable Member Member

Joined: 4 months ago

Posts: 60

05/12/2025 4:07 pm

@polar-bear Sounds good apart from humidity which is too low for furniture and best health.

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Toodles

(@toodles)

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Joined: 3 years ago

Posts: 2328

05/12/2025 4:11 pm

@bontwoody That being ‘She Who Must Always Be Obeyed’ (That ‘A’ in the middle is not just advisory either!) Toodles (50th. wedding anniversary next July).

Toodles, heats his home with cold draughts and cooks food with magnets.

👍

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Polar bear

(@polar-bear)

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Joined: 11 months ago

Posts: 21

Topic starter 05/12/2025 4:20 pm

Ideal ranges

Annual range: 30% to 60%
Summer range: 40% to 60%
Winter range: 30% to 50%

Off the internet just now for inside of house, how would I change humidity anyway?

Outdoor humidity is 88% in sunny South Lancashire just now!

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Toodles

(@toodles)

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Joined: 3 years ago

Posts: 2328

05/12/2025 4:32 pm

@polar-bear That’s what comes of living surrounded by weaving mills! To be serious; dehumidifiers are popular with some people and humidity may be increased by a water feature or just using bowls of water with wicking materials dipping into them. Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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Majordennisbloodnok

(@majordennisbloodnok)

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Joined: 4 years ago

Posts: 1206

05/12/2025 4:39 pm

Posted by: @dgclimatecontrol

↑

@polar-bear Sounds good apart from humidity which is too low for furniture and best health.

So your professional opinion is that good health dictates putting on the kettle for another cuppa to increase the humidity? 😉

Not sure I could disagree…

"Semper in excretia; sumus solum profundum variat"

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