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Heat Pump - where t...
 

Heat Pump - where to start?

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In the longer term we plan to get a heat pump. Our gas boiler had a bit of wobble over the weekend. Which made me realise that due to the lead in/prep work, I don't think we could install a heat pump quickly if the boiler did go. We might have to very reluctantly replace it with another gas boiler.

I'd like to start getting prepared for installing a heat pump and I've seen that I could get an assessment done from Heat Geeks. We've moved into a new place and now is a good time to get some input on any changes we might have to make.

The house is a 4 bedroom detached and nearly 10 years old.

What should be my first step?

 
Posted : 27/01/2025 4:36 pm
triop reacted
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How well insulated and airtight is the house? If the house was built by a mass-builder, then expect it to be barely compliant with building regs and things like air-tightness only a whim. Getting in an energy specialist to do a survey might help as more insulation and improving air tightness helps to retain energy / save costs. Also, don’t discount solar+battery as part of your upgrade - solar charges the battery and use this to heat your water /run the heat pump at night.

 
Posted : 27/01/2025 4:51 pm
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How well insulated and airtight is the house

These are definitely things on the improvements list. I have actually done air tightness testing as a job (albeit briefly).

Solar and battery may come later, so will look to make provision for these, e.g. ease of connection to immersion heater in the tank.

Getting in an energy specialist to do a survey might help as more insulation and improving air tightness helps to retain energy / save costs

I'd hope Heat Geek covers this in their assessment, to what degree I don't know

 
Posted : 27/01/2025 5:30 pm
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Irrespective of what new heating and energy sources you put in now or in the future, get the list of jobs for airtightness and insulation sorted.

 
Posted : 27/01/2025 5:47 pm
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Heat geak survey looks at room volumes, window sizes, doors, wall type, loft insulation, floor insulation etc. It does not directly look at air tightness (though air exchange is in the calcs for each rooms heat loss it's a guestimate). Our surveyor/engineer did say he could show me calcs with different improvements added, e.g if you had thin loft insulation they could show you the calculation of reduction in the heat loss if you topped it up.

 
Posted : 27/01/2025 5:59 pm
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Solar and battery may come later, so will look to make provision for these, e.g. ease of connection to immersion heater in the tank

Arguably pointless if you have a HP as you'll get more heat in the tank using excess solar to power the heat pump than you will directly powering the immersion.

 
Posted : 27/01/2025 6:00 pm
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Insulation is definately the first thing (roof, windows/doors, walls etc). Solar (Photovoltaic PV) panels can make a big difference to your electricity bill if you have south, east or west facing roof  but its always best to link this to a storage battery as well as it lets you hang on to more of what you produce. The battery can also allow you to store off peak electricity as well and then use this during peak hours which can give a big saving.

WRT heat pumps, get a proper survey done before rushing in as it needs a full check of the house and existing heating system to ensure the installation is optimised for your specific property. It also heats the house differently (kind of...think lower temperature say 50 degrees C for heat pump vs 65-70 for Gas). Look up Electric Vehicle Man 's channel on Youtube as hes done a lot of videos on this.

 
Posted : 27/01/2025 6:09 pm
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Talk to Octopus. Job done.

 
Posted : 27/01/2025 6:13 pm
Flaperon and MrSparkle reacted

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I went to an excellent presentation on this a few days ago by an expert. I think he was an academic in the field

As above insulation is king. He had swapped to lower volume intelligent extractor fans too. He’d done radiators and larger volume dual coil hot water tank. Weirdly he switched the pump off all summer and used solar to heat the hot water. But he might have had solar water heating

He had impressive graphs for energy saved and costs per year with his living room at a constant 20 degrees centigrade

 
Posted : 27/01/2025 6:18 pm
 Bear
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Do not talk to Octopus….. and be careful with Heat Geek too…..

 
Posted : 27/01/2025 6:31 pm
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What Molgrips said.

 
Posted : 27/01/2025 6:32 pm
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Octopus gave 50% higher heat losses than heatgeek but couldn't explain the basis of the calculation. They won't supply us as the losses are too high. Heetgeak would but the pump is so big (physically )we have binned that idea.

 
Posted : 27/01/2025 6:36 pm
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Talk to octopus if you’re not bothered about any sort of quality in the install and don’t mind stuff lashed round the outside of your house

 
Posted : 27/01/2025 6:41 pm
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A few simple things you could do. Try turning the flow temperature down on the boiler. If you can be comfortable with this down to 50°C or lower then the good news is that not much else needs to be done. The lower you can get that flow temperature, the better from an efficiency point if view.

There are companies that, rather than calculating heat loss, actually get you to move out for a couple of days, put a known heat source in the house and measure indoor and outdoor temperatures. From there, they can tell you exactly how much energy is required to hit your target temperature.

Last time I looked into this sort of stuff, I came to the conclusion that solar and battery would see a better ROI than a heat pump as my house is full of microfibre pipes and small rads.

 
Posted : 27/01/2025 7:04 pm
 Bear
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Nixie, how big is your house then? There aren’t too many house that are too big…..

 
Posted : 27/01/2025 8:09 pm
Free Member
 

Do not talk to Octopus….. and be careful with Heat Geek too…..

Do you not think a little more background to that statement would be useful?

 
Posted : 27/01/2025 8:37 pm

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Do you not think a little more background to that statement would be useful?

Ok . They use third party contractors . You have no say in who's actually doing. The work and thus little control over the quality.

Its exactly the same for their solar schemes. Hit and miss with plenty of disgruntled customers

But cheap though.

 
Posted : 27/01/2025 8:47 pm
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Talk to octopus if you’re not bothered about any sort of quality in the install and don’t mind stuff lashed round the outside of your house

Conversely I'm very happy with the work Octopus did for me. If you need to get a 4mm cable from the front of the house to the back then unless you want to destroy the inside in the process, you're better off going around the outside.

 
Posted : 27/01/2025 8:53 pm
Murray reacted
 ajc
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Octopus design to 50 degree flow temp so system won’t be particularly efficient. Heat geek design to a lower flow temp and guarantee I think 3.6 for scop so cheaper than your previous gas boiler. You pay for the more premium service though. Most important thing is get someone local. You need someone who will come out and fix it if it breaks. No heat pump designer is going to give expert advice on improvements to insulation or air tightness, especially if you have an old solid walled home. Get an expert for that and don’t do anything skill builder or Charlie diy suggests.

 
Posted : 27/01/2025 8:57 pm
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@bear octopus only deal with up to 220sqm apparently. They calculated around 14/15kW losses which is more than the output of the biggest pump they supply.

House isn't to big for a pump but the layout on the plot means it either has to go on the drive blocking car access to the garage or in the garden where neither of use want a  massive white box. Pipework to to only location for the tank was also convoluted or meant ugly external pipes.

Shame really as I liked the idea.

 
Posted : 27/01/2025 9:07 pm
 Bear
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50 is not that much of a problem with modern refrigerants.
I have a 50 degree flow and am achieving way above 3.6.
it’s only 50 at -3 so most of the time much lower though.

 
Posted : 27/01/2025 9:17 pm
Murray reacted
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Practically speaking, the first step is to understand how leaky (in heat terms) your house is, and what heat requirements it has - in U-value, W/m2K; and kW. That'll give you a clear indication of the output you'd need from a heatpump, how much of that heat would be lost - and where to focus on the insulation/ drafts.

I was lucky to be working with an architect for renovations, and have an HVAC engineer mate; between the two of them I got a solid set of numbers of what would be needed etc. From there I went to a heating company, and they specced the heatpump based on those numbers.

But sounds like Octopus or similar will do all of this for you, saving a lot of hassle!

 
Posted : 28/01/2025 9:44 am
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Yeah. I messaged Octopus, they send someone round, then a team of people is now organising everything except my heat efficiency circuit. They will even remove my gas meter if I'm on Octopus gas for free.  I'm paying £2,400 all in.

 
Posted : 28/01/2025 9:54 am
MrSparkle reacted
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either of use want a  massive white box

Interesting, as I have Octopus coming round tomorrow to do the survey. My front door is very leaky, so I wonder if they'll pick that up.

As for the "Massive white box" - anyone got one they can post a photo up of? My house and garden are pretty small, so I can't see me having something huge outside. Boiler replacement would be more expensive than the heat pump, from what I've seen, as there's no grant 🙁

Good article from a customer here (found when searching for the "massive white box" and finding a reasonably small black one)

https://yorkshirewonders.co.uk/octopus-heat-pump-initial-steps-review

 
Posted : 28/01/2025 11:07 am

Full Member
 

This is the generated picture for the 12kW unit recommended for us and an installed pic from the marketing material. It 1565mm x 1100mm x 449mm though I don't think that includes the feet! If we had side of the house space it would be fine but we don't.

Screenshot 2025-01-28 113454

Screenshot 2025-01-28 113714

 
Posted : 28/01/2025 11:39 am
 Bear
Free Member
 

ADAPT - Kronoterm

 
Posted : 28/01/2025 11:40 am
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Boiler replacement would be more expensive than the heat pump, from what I’ve seen, as there’s no grant 

I always wanted a heat pump for environmental reasons but the reason I have ordered one for late Spring is that my boiler is old and shite and could die any minute (it's already been patched up multiple times).  So I'd rather plan for a £2.5k spend on something I want, then wait and spend £5k on something I don't want.

 
Posted : 28/01/2025 11:41 am
 Bear
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I can do better than the white box, any colour you want! Pipework connections all from below so no visible pipework. Can cover 15kw too.

 
Posted : 28/01/2025 11:42 am
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You may want to listen to the latest episode of "Fully charged" they interview the owner of Heat Geek. He recommends both Octopus and Aira. We spoke to Octopus but they didnt have a HP large enough at the time (we have a 4 bed detached) So we went with Aira. Our experience has been very good, a few issues to resolve but they did so very promptly. The installers were great and did a very good job. They made an error on the amount of 8mm piping we had during their survey but they simply replaced it all without a qualm.

We have Solar and a battery so pretty clued on what to expect in terms of running costs etc. The install cost was quite high even after the grant but they replaced every radiator and all of the piping, installed a large HW tank etc so there was a lot to do. The amount we had to pay was only about £2k more than replacing just our old gas boiler given there were various changes that we had to do to make it compliant (it was around 50 yrs old) now we have all new piping, larger tank and new radiators, overall very happy.

 
Posted : 28/01/2025 12:01 pm
drewd reacted
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Given your house is only 10 years old, it is very likely actually pretty well insulated. Air tightness is a bit of a different story obviously. I wouldn't overlook at least batteries alongside your heat pump. Very low additional investment and very big potential to buy electricity cheap and use it to power your heat pump when it is cold outside.

Depending on where you live, I'd look at alternative refrigerants. I paid a bit more to get a propane based heat pump and have averaged a CoP of about 4.7 across the year. Given the relative price of gas and electricity, test means I'm already saving a lot as the heat leak from a boiler heated house vs a heat pump heated house is no different as long as you stick to the same room temperature settings. Compare that to a colleague who has averaged a CoP of at best 3 across the year and has been getting about 1 in the recent cold (I've been getting 4.2).

Insulating, air tightness, etc. will increase your saving of course. I was lucky to get my solar+battery+heat pump install under the now closed grant and loan scheme. 4 bedroom, 25 year old timber frame house. No radiators needing changed. I'm saving on average 150 a month, which more than covers my interest free loan payments, meaning I essentially "pay back" already.

I'd say, get a new EPC done for your house  ask a few MCS certified installers round, see what they know about funding, pick the one who doesn't annoy you a lot, get it done.

I'd not get Heat Geek or someone else in as, with the age of your house, you should be all good as long as you can get some funding contribution. The longer you delay, the less funding will likely be available.

 
Posted : 28/01/2025 12:45 pm
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my boiler is old and shite and could die any minute (it’s already been patched up multiple times).  So I’d rather plan for a £2.5k spend on something I want, then wait and spend £5k on something I don’t want.

Exactly my situation. But if the heat pump isn't practical. I mean, if it's like nixie's pic... no chance. (My garden isn't quite the size of the one in Bear's pic)

 
Posted : 28/01/2025 1:05 pm
Full Member
 

Our situation as well. Would love one but don't want to see it. If it could go at the far end of the garden that would be great but I understand that adds lots of cost, or a split unit but those don't look as efficient.

The quote for boiler replacement (that includes adding a pump ready hot water tank) is less than half the HP quote even after the grant is taken into consideration. That buys 5-6 years of gas before considering that the new boiler should be more efficient.

 
Posted : 28/01/2025 1:42 pm

 Bear
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That's a brochure pic, just showing there are some better looking alternatives.....

 
Posted : 28/01/2025 3:01 pm
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That's my 10kW unit for an idea of scale. More than capable of handling my 25 year old, 4 bedroom detached timber frame house.20240525_124052

 
Posted : 28/01/2025 5:16 pm
Full Member
 

Just going to add that the life expectancy of a refrigerant system (heat pumps, AC condensers etc) is between 12 and 15 years. New boiler 25+ years. Factor that in if you’re going to be in the property for a long time. It’s also important to ensure they are properly serviced to achieve that life expectancy.

Personally, I love my heat pump especially with the underfloor heating.

 
Posted : 29/01/2025 8:42 am
Free Member
 

New boiler 25+ years

what new boilers forecasting 25+  years ? modern hi efficiency heat exchangers are basically tin foil and are failing well before that - especially in hard water areas.

 
Posted : 29/01/2025 9:50 am
Full Member
 

New boiler 25+ years

sounds a long time. If it is a Worcester Bosch it won’t reach that duration.

Edit. Aside from the un-referenced ‘25+’ year life of gas boilers folks may want to factor in the certainty of higher CO2 emissions than using a heat pump and the uncertainty over gas prices in the next 25+ years.

aiming for a heat pump at ours in the next year or two depending on £ and possible building projects.

 
Posted : 29/01/2025 9:53 am
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New boiler 25+ years.

Pretty sure the gas boiler we removed in June had been installed when our house was built in 1972... Purely anecdotal but talking to neighbours, friends etc over the last couple of years as we have been planning our ASHP install, every one of them complained about reliability of their gas boilers that they had had installed in recent years. Our next door neighbour claimed the warranty etc he purchased a few years ago with his new boiler was the best money he spent and that he calls the company out regularly. Pure here-say I know but I would put big money on every one of those modern boilers being replaced <10yrs.

 
Posted : 29/01/2025 10:01 am
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CIBSE guide M reference service life is 20 years. Good maintenance can extend that and 30 years is not uncommon IME. Hard water shouldn’t affect boilers as the heating water should be dosed and treated to the correct levels to inhibit corrosion.

Not surprising that boiler manufacturers say 15 year life now they have 10 year warranties.

To be clear, I am all for heat pumps and just wanted to highlight a consideration that I am seeing in my line of work where heat pumps are having to be replaced twice to get an accurate 30 year cost forecast.

Also, to be fair, somewhat irrelevant if you move house in 10 years.

 
Posted : 29/01/2025 10:08 am
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@Fat-boy-fat - thanks for that. Looks fine. The Octopus surveyors are here now. The ideal location for the heat pump here is in my bike wash area... they said that won't be a problem, so they have continued surveying 🙂

Interesting that I'll no longer need a gas supply, if I change my oven/hob to electric. I wonder what the savings on that would be...

 
Posted : 29/01/2025 10:26 am

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Well, that's interesting - full survey done - and in the end they haven't got a tank that would fit in my available storage (the old airing cupboard), so a heat pump is a no go currently.

 
Posted : 29/01/2025 11:48 am
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Assuming they mean a tank with adequate volume to sustain recharge times ?

 
Posted : 29/01/2025 11:56 am
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Guess so ? No clue, just said the tank plus it's expansion, current models will not fit. Bit crap if they want all houses to convert, if an average sized 3 bedder can't fit one in.

 
Posted : 29/01/2025 1:03 pm
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seems odd

Assume you had an vented system before ?

telford does a vented cylinder with a heat pump high efficiency coil - im sure others do also.

(no expansion vessel required)

in fairness - an unvented tank with expanison vessel does take a fair chunk of room - ive a 250l unvented with the matched expansion vessel. you would need a very sizable cupboard for it - mines sits in the rear area  behind him garage in an annex/plant room.

 
Posted : 29/01/2025 1:35 pm
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Interesting that I’ll no longer need a gas supply, if I change my oven/hob to electric. I wonder what the savings on that would be…

Our gas bill is about £22/mo when our heating and HW are off.  About £15 is the standing charge. I am willing to bet an induction hob is more efficient than a gas one in terms of energy used, since most of the gas heat goes around the sides of the pan.

 
Posted : 29/01/2025 2:24 pm
Full Member
 

Assume you had an vented system before ?

telford does a vented cylinder with a heat pump high efficiency coil – im sure others do also

All a bit beyond my knowledgebase mate! I've had an independent plumber quote me over 7grand (including grant!) and now Octopus saying they can't do it. Not sure where to go next tbh. Will leave it a few months, see if Octopus come up with another option (or the boiler dies)... see where I am then.

 
Posted : 29/01/2025 2:35 pm
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I don't think you need a specific tank size for the system to work. They are making an assumption of how much water you get through, and since you are heating it up to a lower temp you need to store more hot water. You will only be using water at 40C, but when the hot tank is at 65 you dilute it with cold. When the hot tank is at 50C you dilute it with less cold water so you need more hot.

You do need a longer or finer heat exchanger in the HW tank though so assuming you can find a smaller tank with a suitable heat exchanger you could persuade them to fit a smaller tank that will fit in your cupboard, and sign a waiver to say that you won't complain about there not being enough hot?

 
Posted : 29/01/2025 3:10 pm
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Well, they asked about occupancy - ie. just me at the moment - but were talking about if I came to sell up and potentially a family of 4 could move in... We didn't discuss that further... but I don't know if they only looked at 4 person occupancy or, smaller capacity (I don't care if a new tenant runs out of water!). No idea, wasn't given any options, so I guess I'll see if the survey comes back with details.

 
Posted : 29/01/2025 3:31 pm

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 I came to sell up and potentially a family of 4 could move in…

That thought entered my head about the tank size and house size. It is good to know that some thought is being applied by the installers even if it isn't by the current owners!

My combi boiler has developed a fault and I'm reluctant to get it fixed straight away. I'm going to see how I manage with a gas hob/electric kettle for water heating, no gas central heating or hot water for showers. So I've joined a gym (shower) and I'll equip myself for a shower at work. A slight routine change will be needed but I might be able to make inquiries into electric heating and water but not using a heat pump?

 
Posted : 29/01/2025 3:51 pm
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Don't expect much back other than the survey fee. They would not give me the details or calculations once our house had been deemed unsuitable.

 
Posted : 29/01/2025 3:52 pm
Full Member
 

Well, that’s interesting – full survey done – and in the end they haven’t got a tank that would fit in my available storage (the old airing cupboard), so a heat pump is a no go currently.

I could be talking rubbish, but I think you could fit an air to air heat pump, which circulates hot (or cold) air around your house, so you'd keep your existing hot water tank, which would work from an immersion heater (maybe via panels and battery).

You'd need to fit alot of ducts around the house, but it would be air conditioned in the summer.

 
Posted : 29/01/2025 4:51 pm
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