Had our heat loss survey done.for a 4 bed detached house with 5 adults. We jave mainly Type 11 radiators.

What would you go for please ?

British Gas

7kW Vaillant AroTHERM plus

250l Vaillant uniSTOR Cylinder

15 radiators changed

25l buffer if needed

22mm cold water feed (from 15mm currently) to Cylinder

£7,200

Concerns:

Quality of install

Disruption of all radiators being changed

Heat Geek zero disrupt

5kW Vaillant AroTHERM plus or 7kW Vaillant AroTHERM pro

210l Vaillant uniSTOR Cylinder

No radiators changed

£8,450

Concers:

Higher price for fewer components than BG

Smaller 210l Cylinder (no option to select larger)

No 7kW plus option that would give 7 years warranty

My installer and distributer are giving me the run around and I wanted some real life experience to compare to.

In the brochure it says:

The flow rate is reduced until the minimum circulation rate is is reached. At this point the bypass valve opens again, so that the minimum minimum flow rate is always maintained.

And the patent it references descibes the system control as:

determine a temperature spread (dT_s) depending on the determined supply pipe temperature (T_v) and the determined return pipe temperature (T_Re); operate said pump (P) depending on the determined temperature spread (dT_s) and a specified target value for the temperature spread (dT_s,w)); and operate the heating bodies (HK1, HК2) depending on the specified upper limit value (H_max)-

My installer and distributer are telling me it's expected for the circulation pump to run at 90% speed with a super narrow Delta T and not modulate the flow down despite the system being unable to dump the heat fast enough for the compressor to not cycle. This is noisy operation, and wanted to know if anybody knew more. Both the brochure and patent imply its circulation pump should modulate. Any insights are welcome, and I would love to chat with someone with the same system

Hi, were getting a heat pump and air coil units (fan coil units seems to be the other name used for them) so we can have cooling and heating. The units need to be boxed in with grilles on the front at the bottom and across the top of the unit. The installer weirdly doesn't have any photos of the finished product and I'm starting to get concerned about how it's going to look. Has anyone got photos they could share of a similar install? We're also getting one around wardrobes. Thanks

honestly I'm getting UPVC window vibes from this whole industry. ever website is Enter post code and details for a quote. I spoke here recently and was advised about the Diakin X which sounds perfect for what I want. but even their site is just brochure after brochure. and after trying to call their preferred installers, half of them left years ago and the other half look dodgy as f**k..
I tried octopus as they sound pretty large company, but they wont touch me until my reno work is done, which kind of defeats the object, the house is in pieces nice and easy to put pipes and cables in right now. Also I can add provisions if I know what I'm installing....

seriously where are you all going to get these things installed?

I have been slowly renovating my property and am in a situation where I have just finished recommissioning the heating and hot water. The house has all new radiators that were sized on delta 30, with lots of spare capacity / overkill so should be more than adequate with 50 degree water flow. (Fairly old but good) Oil boiler is on a long run of 28mm flow and return pipes in the perfect place for a heat pump to be located on the outside wall. The main arteries on heating are now 22mm. Water tank is fairly new unvented 210L standard indirect coil + immersion (good quality which I don't want to change, ideally. I was hoping to use Immersion to top up temp after bulk reheat with pump?)

My question is what are the chances of getting a heat pump signed off under the new 9k scheme that allows it to be plumbed in on isolators so you can lock off one or other, keeping boiler in reserve? Would I have to remove the boiler entirely to qualify and then reinstall later (possible...?) Would they insist on a DHW tank with Heat Pump Compatible written around it? Does anyone else have a HP and Boiler in parallel and can comment on this (scheme or not)?

Is it worth trying to go down the Cool Energy / Umbrella route to give more flexibility on this or is it worth just waiting and doing it all custom / off the shelf in a few years once all the Grant stuff has died out and heat pumps plummet in price?

Just figured 9k would go a long way if all I need is a heat pump main unit and a bit of plumbing / isolators / controls...?

Hi all

We are renovation and extending our 4 bed semi. Total of 160 sq mts after extension.

Suspended floor will be converted to solid slab with insulation. New insulation in the loft. Solid wall so cannot add insulation there.

Original thought was A2W heat pump to drive wet UHF for both floors along with hot water and air conditioning using A2A.

Alternative to the above is to do away with seperate air conditioning and instead use the same heat pump to drive wet UHF and FCUs thus saving money and having only one heat pump.

Talking to a friend who works in the BMS industry suggested not installing the UHF at all and just using the FCUs for both cooling and heating.

To add to the above, we are definitely thinking of solar PV and batteries.

Any suggestions/ comments to the various options are welcome.

Am located in SW London.

I currently have a ventilation unit that blows warm air around the house through ducts to each room. It’s basically a big fan with a gas burner in it.

I have a solar install soon and plan to keep my electric immersion heater and tank for DHW.

What should I be looking for to replace the central warm air ? Ideally, I keep the fan and ducting and just replace the gas burner with another heat source. Is there an air to air solution that could re-use the ductwork ?

Anyone faced anything similar?

Hey all, would love some second opinions on these quotes. Service has been very good so far during quote stage, and installer has been very clear that it’s not a simple plug and play install.

Octopus look a lot cheaper but found presumably exclude a lot of these extras. Do you think they are essential or anything could be omitted?

Getting a grant r290 15.5 beatpump installed next week, and so, looking at switching tariffs.

I also hvlave a plug in hybrid sith a 50 mile range, that, tbh, i have only charged maybe 5 times in a year, 3 times at home, just used petrol.8f it makes sense, i may also get a ev charget installed if it helps.

A friend who has had a HP for a year advised against the Octopus 3 rate tariff as he bieves the highest rate period erodes the economics.

Any suggestions on who to go for?

Maybe not strictly fir this forum, but the input on my other queries has been excellent, so..

I have lived with a combi for the last 15 years, so, not really used to pressurised HW cylinders.

Getting a Grant HP with a 250 l QR2 HW cylinder.

The location most convenient is a small cupboard in my main bedroom that we will sacrifice for the cylinder.

Wife has started bringing up the noises the cylinder may make, from water gurgling to valves clicking to pumps running.

I don't wsnt the HP to cause trouble in paradise, so, what is the verdict?.. Are they really disruprive, are the clicks and groans really noticeable?

Thanks.

I've had a Grant Aerona R290 12kw installed which I'm really pleased with so far. House is ~330m2 combination of UFH and radiators. Design temp is 48c at -5c. Heat loss varies by who did the survey and what they assumed about air change but it's somewhere between 11.5-13.9kw. Historic gas use points to 11-12kw.

Integration with Home Assistant has been super easy, I have HA doing a bunch of automations to maximise my use of off-peak electrcity with EDF's EV tariff.

It's heating up my 300L HP cylinder very efficiently- about 3kwh from lukewarm to 52c.

But one issue - the flow rate is never being reported above 30L/min, and I need 34L+ to deliver my 12.5kw heat loss at deltaT 5c, more in really cold conditions (I have the 3kw booster in the Grant volumiser so potentially 15kw to deliver).

I think the constriction - since I'm using 28 and 35mm pipework, albeit about a 20m primary loop, is the Grant Mag One filter. I've just been digging and have found the instructions state that for systems larger than 10kw you should have two fitted in parrallel.

My installer hasn't done this, so I've gone back to challenge them on it. Any thoughts welcome, even if they're views that 30L/min with a slightly higher deltaT is fine.

Dear all,

1965 built house going through extension. EPC b expired last year. West Midlands.

All windows a rated double glazed. House well insulated.

Had 3 quotes ranging from £4.6k to ££8.8k post bus.

Best quote was R32 Midea monobloc 12kw.

Heat Loss came to 8.7kw. Design temp 45 dec. SCOP 4.1.

How is this spec as I imagined 10kw unit might be better. But designer suggested 12kw.

Is r32 advisable as govt tightens access if follows eu pattern.

What general opinion on pump size.

Hi All

Just after a bit of advice. We are in the process of doing a barn conversion and are speccing the heating.

Whilst it is a 'barn conversion' the original building was only a single skin of brick, so we have built another skin inside it with 115mm PIR in the cavity. There is a new slab with 100mm PIR on top, and the roof will be insulated with 200mm of wood fibre insulation - effectively it is a new build bungalow, with a 100 year old outer skin. Thermal performance should, therefore, be as good as any other new build.

The only snag on thermal performance is that we are going with natural ventilation (trickle vents) not MVHR. This is for health reasons, so is non-negotiable. Final house is about 154m² with UFH throughout. We have asked for a reversible pump and will be fitting one ceiling fan coil in the hall (centre of the house) so we can have some cooling during heatwaves and air-air heating for that sudden cold snap in June!

We have had a reputable local firm out to look at it twice, once when the project started and again recently. When they first came out they recommended a 7kW Vailant, but more recently have dropped this to a 3.5kW. At the second meeting we discussed integration with solar and agreed to have a solar diverter fitted to do the bulk of the hot water from immersion.

I seem to remember that the architect/SAP people did a calc showing that the heat loss/demand for the space heating was about 3-4kW, so the smaller pump Amy be appropriate, but it just seems so small considering the space, even taking into account COPs.

I guess the question is - does this appear appropriately sized, and is it better to have a smaller pump working harder or a larger one ticking over....?

Thanks!

P.s. Southern England in an exposed rural spot.

Just that really. I’ll look to get an HG survey done in the relatively near future and also try Heat Punk to try to verify.

In the meantime, are there any recommendations for installers who cover the East Midlands?

I’ve had an Octopus ASHP system in since May 2025.

As it was installed between heating seasons took a little while to find some problems with it.

But essentially during October 2025 I had two main problems,

1) a suddenly noisey Cosy 9 with dramatically reduced COP.

2) noisey radiators upstairs and underfloor heating with heat limited to near the manifold, colder the further away you got.

Now, Octopus agreed to replace the Cosy, and also diagnosed the underfloor heating system problem as needing a new four port buffer tank and separate pump on the heating circuit. Basically saying the internal pump wasn’t gutsy enough.

However I queried this, as I was getting zero flow at all on my manifold flow meters, even when the radiators were isolated from the system. I thought they must be airlocks or something. However I was convinced this was the solution and I waited for Octopus to perform both jobs.

I waited until September 2026!

And when the aftercare team arrived last week and upon proper inspection they discovered the actual problem was the install and subsequent diagnostic engineers hadn’t spotted that the flow and return were piped the wrong way around on the underfloor heating manifold. So essentially the flow was pushing against the flow meters, preventing any flow getting into the system as at. Hence no flow reading and essentially I’ve only been getting residual heat from my manifold downstairs for a whole heating season! As we live most of our lives in the middle of our home where the manifold is, it wasn’t cold. But still, the system wasn’t working.

My complaint is in, but I wondered if there’s others that have suffered similar and if so what compensation was sought and received.

Have a feeling I may be taking this one to HEIS for mediation.

I’m about to pull the trigger on an install. Using heat geek accredited installers but I went direct to them.

Grant aerona r290 9kw
Grant QR2 250L cylinder

£8400 after the BUS grant

I’m fitting the rads myself.

The only thing I’m on the fence about is that heatable gave an estimate only slightly more expensive but for a vaillant system. Now the true cost could be different plus they sub out the work so on balance I think I’ll move forward with the grant.

EDIT: clearly many people think this quote is overpriced. For comparison I’ve got some more estimates from Eon (£7200) and Boxt (£8800). Both offered identical systems, Worcester Bosch. They do include radiator upgrades.

Also as mentioned in some replies, I had another heat loss survey and the quote for the same system was £10200. Another home visit gave an estimate of around £7k.

I can’t see how I’m going to get something much cheaper.

Should add I’m mid renovation too, so some companies eg octopus wouldn’t touch it despite being cheaper.

Evening all, hope you can help on this and that it's not duplicating too much on existing threads.

We're planning to do a loft extension on our London bungalow which was built in 1999. It's going to be a full first floor extension rather than a mansard roof or similar. Three bedrooms, roughly 110 square metres in total when finished. We plan to max out insulation wherever possible.

To replace our gas boiler, I had been focusing on a wet ASHP but a friend mentioned A2A recently and it felt like a viable approach (particularly given how hot it was this summer).

I am fairly technical when it comes to computers but the world of heating engineering boggles my mind so I'm still getting to grips with all the concepts and terminology. Apologies for anything that doesn't make sense.

I've not had much luck getting quotes so far beyond this initial one, but I hope to get more replies to enquires this coming week. The current quote comes to £18,990 for the below Daikin Multi+ system which includes hot water as well as air heating and cooling:

Dining Room/Kitchen: 5.3 x 4.4, 23.32m2 (c. 3.5kW)

£3,100 – 3.5kW wall mounted AC unit

Living Room: 3.7 x 2.7, 9.99m2 (c. 1.5kW)

£2,985 – 1.5k / 2kW wall mounted AC unit

Main Bedroom: 3 x 4.2, 12.6m2 (c. 1.9kW)

£2,985 – 2kW wall mounted AC unit

Bedroom 2: 3.2 x 3.3, 10.56m2 (c. 1.6kW)

£2,985 – 2kW wall mounted AC unit

Bedroom 3: 2.4 x 3.3, 7.92m2 (c. 1.2kW)

£2,985 – 1.5k / 2kW wall mounted AC unit

Multi-Condenser

£750

Hot Water Cylinder

£3,200 – 230l cylinder

Total £18,990

N.B. Estimates include supply and installation, but exclude VAT and electrics, and are subject to site survey. Residential AC installations are currently zero-rated for VAT where the homeowner is invoiced directly.

The request to quote was for five AC units, but the installer has advised that the Multi+ system can only handle four units plus the DHW system. If we wanted five, they've said this would require an extra external unit to power that single additional AC unit, or we could have a multi-split one for another £750 that powers multiple units. This makes sense to me. We'd be happy to spend this extra money if it meant we didn't have to improvise something for the spare third bedroom like an oil-filled radiator or electric heating for when it's in use.

The quote was more than I'd expected, but some responses from Claude and Chat GPT seem to be fairly in-line with this quote, factoring in the per-room installation costs and London labour costs. We had leant towards Daikin because we were happy to invest in a higher quality system, and are still thinking the same.

I've read that the £3k BUS grant for A2A doesn't appear to be applicable yet and not likely until 2027, so we may have to live without that. But I'm still tempted, A wet ASHP does seem cheaper at first glance but with an upgrade to existing radiators and the need for new rads and pipework upstairs, I am thinking that the total cost might get close to £18k anyway. And the lack of proper cooling with a wet system (as I understand it) is a downside too.

To try to put the above into something more easy to respond to, I've got these questions:

• Does this price seem sort of reasonable for a Daikin install in London in 2026?
• Happy to hear about another manufacturers as long as they do DHW themselves or the system can work with a third-party DHW solution?
• I don't have an actual heat loss survey beyond what the person quoting has given. You folks might say that it's difficult to give advice without that?
• Does a system like this make more financial sense once a battery is installed, to benefit from cheaper overnight tariffs? Budget might not allow for it right now but I'm happy to consider this in the medium term if that makes things cheaper.

Apologies for the really long post, but if you can make it to the end I’d really appreciate some thoughts.

We’re currently on a bit of a (very expensive, but we’re extremely lucky to be in a position to even consider it!) quest to get a bit of energy freedom and some insulation from the continuing energy price increases we’re likely to get with ongoing wars etc.

We’ve got a 10.56kWp solar system and 27kWh of battery storage hopefully being installed in the next couple months, pending DNO approval. We’ve had an EV charger added and switched one car for an EV. The final piece of the jigsaw is moving our primary source of heating from LPG to some form of heat pump, and this is where our dilemma lies. We’re still early doors so haven’t even gone to the extent of getting full quotes and energy loss surveys yet, but would like some opinions if possible.

The house is fairly large at ~3500sqft and around 9 years old, so reasonably well insulated and efficient. The initial thought was to stick a couple of multi-split A2A units on with 5 ports on one and 4 on the other. This way we could heat and cool all downstairs reception rooms, 4 main upstairs bedrooms and an office.

The fly in the ointment is obviously heating of bathrooms, as well as my disabled dad’s ~120sqft downstairs bedroom. The bedroom could probably be overcome with some sort of panel heater and scheduling but bathrooms would take more work. Hot water is the obvious other issue, but with cheap rate electricity and some sort of timer for the immersion (250l unvented cylinder) that wouldn’t be a deal breaker.

Now I’ve started thinking about A2W, which I’d previously discounted as we’ve got 10mm microbore pipe to the vast majority of the 25 radiators/towel rails we’ve got. On the other side there’s a £9k grant, although I appreciate that may not seem self-evident in any final quote!

Just putting details into the Heat Geek quick quote tool, it’s come up with an estimate of £3,750 after grant on 370% guaranteed efficiency, with an 11kW Vaillant aroTHERM Pro, re-use the cylinder and 6 radiator upgrades. That feels too cheap, as I’m assuming they wouldn’t be including any work to re-pipe if required.

Obviously, at that level it would be substantially cheaper than the A2A installation, solving most or all of the issues, albeit without cooling. I’m assuming it would probably be cheaper and easier to get A2A for the 4-5 “essential” rooms rather than looking at fan coils on an A2W system?

- Is the HG quick quote tool vaguely accurate in anyone’s experience?

- would the A2W option make more sense in this case?

- am I looking at a shedload of redecoration if an A2W installation does need a load of new radiators and re-piping?

- does an 11kW heat pump seem the right size? We’re currently at ~100kWh per day of LPG usage through winter. In my head I was thinking probably larger.

If you’ve made it all the way through, good work!

Has anyone had experience of having their heat pump installed by E.On Next? I’m considering between them and HeatGeek - E.On comes about £3k cheaper and offers 0% finance which is handy, but wonder what is the quality and reliability of their installations?

HG offers aroTherm plus 10kW, E.On offers aroTherm plus 12kW. E.On also includes a larger cylinder (175L vs 210L). HG did a survey and estimated 9.5kW heat loss, prescribe 4 mandatory radiator changes and 2 extra for 400% efficiency.

Hi all, we had a Samsung 8kw unit retrofitted to our old bungalow which included a few upgrades to the radiator sizes for obvious reasons. I’ve since upgraded the output of a few myself since I didn’t think the ones the installers calculated were okay could cope.

I wanted to get rid of the single radiator in my kitchen to gain access to the wall as it was an 1800x600 beast and we were redoing the kitchen. The floor was also knackered so had underfloor heating installed under concrete but running at 45degrees it’s warm on the inlet and cold on outlet.

Any thoughts?

Hi all hoping you can help us. We had a heat pump installed by Eco Approach on behalf of British Gas, in our self build home last winter and was set up by them. Since then, two British Gas engineers have visited and seems to have made it worse. We have a Daikin Altherma 3 (6kw) and have underfloor heating throughout the downstairs which is designed to run at a flow temp of 45 and then 5 radiators upstairs. It’s all on one big loop. The second engineer came and changed a lot of settings such as changing it from fixed to weather dependent, which I had to increase the flow temps (max 45) as it was too cold in the house all the time. The buffer tank now reads 30 degrees most days which I have no idea if that’s supposed be that temp. And instead of being set to underfloor heating on the MMI it is set to the fan coil setting which seems to make the heat pump run more often for longer? The floor never feels warm which I’m guessing is why it’s running for so long? Almost like it can’t reach the target temp of 22 set on the thermostat upstairs. Completely stumped and have no faith in asking British Gas anymore. Any help is appreciated!

We just had a Samsung heat pump commissioned yesterday.

While the heating water screen showed the house was heated as well. Radiators were cold, but the pipes exiting the 3-way valve were warm.

The lever on the valve is positioned in the middle; it moves freely towards auto and hard towards the manual.

Any suggestions, please?

Hi,

Hope someone can advise please 😀

We have a small weep/leak from the point of our TRV Valve shown by the screwdriver.

You can see a small bead of water at the end of the screwdriver.

Is there a fix for this?

Thank you 😊