r/ukheatpumps

I would first caveat that no heat pump user should use a default electricity tariff. However, the energy price cap is illustrative about the general trends.

Compare July 2025 to July 2026:

1. Electricity: 1.16% increase from 25.73p/kWh to 26.03p/kWh
2. Gas: 13% increase from 6.33p/kWh to 7.16p/kWh

Now, some of this are due to policy changes made by the government. However, given there's only 5% VAT on gas it is inherently the case that electricity has more room for manoeuvre. Electricity has tons of added policy costs which could be shifted without too much unintended consequences.

Combined together this means that the heat-pump user will be experiencing far more consistent heating costs over this period of crisis than the gas boiler user. For those who want sustainable bills which fluctuate less during crises the choice should be obvious.

How to educate the public about the need to innovate to reduce price volatility is a hard problem but these data certainly helps.

Mam's boiler is on last legs so doing some sleuthing on this. With the BUS it's still looking at 4-5 grand (the cylinder seems to really push that up). We don't need any radiators sorted as they're all modern when the houses got upgraded in the 2000s (right-to-buy). My question I guess is, the price seems to be largely for an air con system that costs 5 grand. Are there not cheaper ones ? Or is this just the general cost of an air to water heat pump ?

I've looked at air con systems over the years because we all have at some point with this bloody weather! And there's tons of really powerful ones that seem to cost a grand or 2. Is that just for air to air ones ? I guess what I'm asking is, does anyone have experience with especially cheap air-to-water + cylinder BUS-paying installations, where they didn't regret it because "you get what you pay for" ?

They're both pensioners and I'm on long term sick (broken back) so even if I could help out, I won't be back in work for another year or 3. And the boiler has just been tagged as dangerous, and needing an £800 valve something or other. Seems daft to do that on a 25yo boiler.

fwiw I am completely in the dark in ALL of this. Been trying to google around so I'm not coming in completely daft, but yeah slow going. If I can get this going, then maybe focus on air-air next year and just get a cheap version of that when I'm back in work

Started thinking about heat pumps last winter when the boiler in our Grade II mid-terrace started throwing lockouts. It's a 2-bed Victorian in a Cambridge conservation area. Combi's now on borrowed time.

Ran an ASHP survey in the spring. Rear yard's about 4m by 3m, north-facing, and the rear elevation is visible from a footpath the council counts as public realm. Both the conservation officer's pre-app letter and the planning duty officer's follow-up made clear anything on that elevation would need full listed building consent, and the tone wasn't encouraging. Front's off the table for the same reason.

MCS designer came back last month with an indoor R290 monoblock as the alternative. Idea is to site the unit in the ground-floor utility off the kitchen with a pair of ducts through the back-of-house extension. The extension itself is post-war brick, which the designer reckons is the least sensitive route to bring the listed consent through.

Heat loss came out at 4.6 kW at design conditions (the loft's been done and the cavity's insulated where it could go), which suits the 4.8 kW model in the range being proposed. Installer's leaning toward keeping the existing 180L cylinder and running the whole thing off the current rad circuit at 45°C flow. Specific unit being spec'd is a PHNIX airMono R290 4.8 kW, which the installer says is one of the few R290 indoor monoblocs he's taken through Conservation consent so far this year.

Two things I'm not sure about. Manufacturer's quoted 58 to 61 dB indoors, which sounds significant for something sitting behind a stud wall from the kitchen. DHW mode COP also runs lower on indoor monoblocs because the source air is ducted. There's also the MCS listing question for the airMono, which the installer says is pending because it's newly launched, but I'd rather not commit to a spec that misses BUS grant timing. Being new to the UK market also means the installer network's still small, so aftercare access is a fair concern versus mainline Vaillant or Mitsubishi.

If anyone here's running an indoor R290 monoblock, real-world noise experience and whether the ducting install was intrusive would be helpful.

ETA:

Settings I've changed following fantastic advice from everyone.

Lowered heat curve from 0.70 to 0.40 Lowered flow temp from 55 to 45 degrees Heating schedule tidied up to go from 18 to 20 degrees.

I've learned a lot from this post and will be making adjustments as I go from here.

Thank you!

Original post:

Hey folks,

Moved into a new build in June and finally done a bunch of research for the schedules and changed to a TOU tarrif to suit, tarrif starts on Thursday.

Vaillant arotherm, 3 bed end terrace.

What I'm noticing though is it's TOO warm.

I'd be extremely grateful if anyone can take the time to review my settings and make any suggestions to anything I might have missed.

I'm in Scotland. My control module is reading indoor temp 24 degrees, outdoor 16 degrees. The highest temp I have set is 21 degrees for a brief pre-heat.

Current schedule (we work day and nightshift from home):

Heating (setback is at 18):

Mode: time control

7 days

0000 - 0200 19 degrees

0200 - 0400 18 degrees

0400 - 0600 21 degrees

0600 - 1600 20 degrees

1600 - 1900 18 degrees

1900 - 2300 20 degrees

2300 - 2400 19 degrees

DHW:

Mode: time control

Temp: 55 degrees

7 days

0300 - 0400

1500 - 1600

Circulation:

7 days

0630 - 0830

1430 - 1600

1900 - 2100

Circuit 1 installer config:

Target flow: 0 degrees

OT switch off: 14 degrees

Heat curve: 0.70

Min flow: 15 degrees

Max flow: 55 degrees

Set back mode: normal

Room temp mod: active

I feel I've included more detail than needed just for heat but more the better, right?..

I'm a bit baffled how indoor temps are reaching 24 degrees.. It's hot in the whole house.

Thank you so much x

Hi there, I've got a trianco activair heat pump and a Telford hot water cylinder. The heat pump is 'slaved' to the hive thermostat and so can only control radiator thermostat. The domestic hot water tops up as and when and can't be timed.

Is this the most economical way to do it?

Many thanks

Tom

Hi folks - I'm a journalist researching some stories (nice ones, not hit jobs) about homes that have switched from oil heating to heat pumps.

Looking for examples in Scotland only. I'd love to hear how it went, what any issues were during or after and whether you'd recommend it to others. Thanks!

Since getting solar I've been massively looking into heat pump solutions since my boiler is 15 years old and the cylinder is wrecked with limescale. Earlier this year I got a few air-to-water heat pump quotes and very nearly pulled the trigger.

However I have since learned about air-to-air (A2A) heat pump systems and now realise I would much prefer to have this setup since it can both heat and cool the house, not to mention more floor space from no radiators and the government announced that A2A can now get a £2.5k grant on the boiler upgrade scheme.

After research, speaking to suppliers, heat survey, etc I know I want something like:

- Downstairs 4x Stylish units + 230L water cylinder and Multi+ outdoor unit (all Daikin).

- Upstairs ducted zonal system for 3 rooms fed by a second outdoor unit (unsure of best brand for this).

The issue I've been having is I can't seem to find a supplier who can do all this. Air con companies can't do the hot water cylinder stuff and green energy / heat pump companies seem to only do air-to-water systems and seem baffled by the concept of A2A. If I split the work between multiple suppliers then, aside from extra cost, I'm not eligible for the grant (as far as I can tell) because I'm not upgrading the heating system on any single job. I've only found 1 supplier so far who seemingly could do everything, however they did not have the accreditation to be able to get the grant and were also booked up with work for the foreseeable.

Would love to hear any advice, ideas, suggested supplies etc from others who have A2A or have also been looking into it!

Currently in our two up, two down with attik mid terrace we have no central heating system.

Should i go for a traditional Combi boiler central heating system or a heat pump system, if so, woukd you recommend a wet or air to air system.

We are a mid terrace home with a small rear garden.

Have been quoted £3,000 for a combi boiler central heating system. Can afford this but we are very tight on money so would not be able to afford call outs for any repairs to a heat pump system.

So confused as all of our friends and family are telling us of nightmares with heat pump systems and im so confused.

Looking for some advice.

I bought my 2 bed terraced home last year (live alone) and it has electric radiators, which we know are expensive to run, especially in the winter. I have been approved for the grant scheme for an air source heat pump and have had a fair few quotes. There is no gas in my home.

The last company advised me it could cost me more money to run an ASHP than what I'm already paying out in electricity; the other companies suggested it would be cheaper. For context I'm approx £50pm since March but during winter I was ~£200pm and that was with my heaters on the miminal time required to take the ice out my toes/fingers and wearing layers all winter.

I really cannot face another winter like that and being quoted around the 15k mark just for the ASHP and installation. I don't expect to be in this home in 10 years so installing solar etc isn't something I am now considering.

The cost isn't really my concern as I just want a warm home that isn't going to bankrupt me or cause me long term issues but I see so many mixed reviews I really would just like to know if those who have now got it found it worthwhile?

I am considering getting gas installed and my other option is of course to put in more energy efficient radiators. My brain is exhausted with it all and I am now finding it overwhelming.

Any advice is welcome 🥲

Hi, short and sweet.

5 bedroom house medium insulation EPC currently C.

Boiler on the brink

Had a quote from octopus for a heat pump (with the £7500 grant), 14 solar panels on a south facing roof (with the 20% saving on VAT currently) and a Tesla 3 11kwh battery.

Comes in roughly 21k.

I could go for planning and put 20 panels on and then export more as the Tesla battery is supposedly the best one and can handle all this bringing me to a net positive on cost/return each year (accordingly)

Any input on this? I see conflicting things absolutely everywhere.

I posted around 9 months ago about COP being 2.1. Since then I've had the installer and manufacturer (Vaillant) out quite a few times to fix various issues. They've told me to ignore COP as Vaillant is very inaccurate and the only way to really know is to (pay them) to install an external piece of kit.

Basically, I want to know how accurate all that is or whether I'm getting fobbed off?

I have near 12 months of data now, however, there does seem to have been some technical issues with the Vaillant heat pump. These were only addressed in June, so I don't know how relevant the data before is. And, over the past year there have been quite a few setting changes.

Currently only using DHW and only for the sinks and occasional bath (not for the shower), so not as efficient as heating. This doesn't paint a full picture, but I want to get ready for the next cold spell so I know what to look out for.

Post-fix COP for July was 1.69 and for August so far is 1.57.

I've now cross-checked the app's electricity consumption against my Octopus smart meter twice. They match within a few percent. So the electricity side isn't the problem.

The setup:

• Vaillant aroTHERM plus 5kW (VWL 55/6, R290)

• sensoCOMFORT VRC 720f/3 controller + VWZ AI interface

• 1930s end-terrace, 3-bedroom, Edinburgh

• Heat loss: 4.78 kW at -3.5C design temp (86 m², 56 W/m²)

• Filled cavity walls (U=0.45), double glazed, 100mm loft insulation, solid floor insulated

• Radiators: 2 replaced, 4 added, 6 retained (all rooms meet 100%+ demand at 50C flow)

• Heat curve 0.70, design flow 50C, max 55C

• Vaillant 200L pre-plumbed cylinder

• DHW target 48C, cylinder charging offset 7K

• Backup heater off (bivalence -30C)

• Quoted SCOP at 50C: 3.41

• The timeline:

• Sep-Dec 2025: Heating COP 2.29, DHW COP 1.36. Already well below the 3.41 SCOP and what others here report.

• Jan-May 2026: DHW COP slid further to 1.09-1.23. Environment energy ratio in the data was near zero — the compressor was basically acting as a resistive heater.

• Jun 1: Vaillant engineer visited, tested heating at COP 1.88. Said nothing was wrong.

• Jun 5-15: COP got worse after the visit — DHW dropped to 0.37-0.93.

• Jun 16: Second engineer visit. Energy counter was reset, a new device serial appeared in the CSV data.

• Jun 17 onwards: DHW COP jumped to ~2.1-2.2 on normal days. Environment energy ratio came back to normal levels.

• Jul-Aug 2026: DHW COP averaging 2.15, best normal day 2.90. Heating test in late June gave COP 2.65-2.80 at 17-21C outdoor.

u/GFoxtrot posted in my original thread with the same 5kW Vaillant in a similar 1930s property — COP of 4.1 combined in November. Even post-fix, I'm nowhere near that, despite a similar heat loss (~6 kW vs my 4.78 kW).

For those with the same unit, how far off are your Vaillant app COP figures from independently measured numbers?

And has anyone else been told the app is 'very inaccurate' — is that a known thing or just a way to deflect?

Hello!

Our heat pump's scheduled to be installed this week in Scotland, Monday-Friday, and seems it'll rain for most of the week. This is our first home and having this level of work being done inside the house. Of course we'll offer water and move things out of the way before they start but wondering do you guys prepare anything for the installers during their work hours (i.e. lunch, snacks, etc)?

I think maybe it'll help them do a better job but my husband said it depends on the person as sometimes they just want to focus on getting the work done.

Thanks!

I currently have a vented hot water system with a loft storage tank and a heat-only gas boiler, but as part of my renovation I want to upgrade to an unvented cylinder. Longer term, I’d like to switch to an air-source heat pump, so I’m considering buying a heat-pump-compatible unvented cylinder with a larger coil now and simply running it from my gas boiler in the meantime. My understanding is that the larger coil is needed for the lower flow temperatures of a heat pump, but I’m unsure whether there are any disadvantages or problems with using one with a gas boiler initially. Is this a sensible way to future-proof the system, or would I be better off buying a standard unvented cylinder now and replacing it when I eventually install the heat pump?

Just wondering what are people's opinions on Nibe heatpumps? More specifically would there be an issue with going with their f2050 range which uses R32 instead of s2060 which uses r290?

I'm getting quotes for an AC unit, and for my living room, we want to place the outdoor unit corner of the front drive. I'm just worried if that's allowed under Permitted Development. Anyone in London have experience with this? Thanks!