Welcome to the forums, and I'm glad you're being thorough and that you have identified the red flags. That's a massive part of getting a decent installation. Where in the UK are you based?

@editor Hi Mars. Im based near  Newcastle upon tyne in the North East of england.

PS. my pipe work is already 28mm . heat loss was claulated as 9.8 and 10.9 respectively. a Vaillant aro therm plus

10/12 kw double fan unit has been suggested by both.

@redguy17 How handy are you in a diy sense? Both heat pump and batteries can be installed by a savvy diyer. I’ve installed two heat pumps myself to good effect and there is lots of help on here for a battery install. Check out Glyn Hudson on YouTube if you fancy it.

@bontwoody Good on you and your DIY mastery to install two heat pumps and batteries. I on the other hand have little to no Diy skills and a very particular wife ! Diy isn't an option im affraid. I may have to look in to Air to air/ aircon as a solution.

@redguy17 lol, I cant claim to have installed the battery but there are people on here who would help. Air to air is fine if you are comfortable with blown air heating. We have one in the kitchen which is difficult to get radiators into.

This situation provides a good example of the challenges of retro-fitting heat pumps to existing housing. Is there a technical reason for not fitting cavity insulation as this would reduce the heat demand and thus enable a lower flow temperature?

Getting the woodburner to contribute several kW of heat whenever the weather is very cold (eg below 5C) would change the sums significantly by enabling the heat pump to run at a lower temperature and make a size smaller heat pump viable. I've got both a woodburner and a 3-way multisplit air-to-air system that were installed prior to the heat pump. I've used the former on some cold evenings more out of curiosity to see how the heat pump responded rather than due to a lack of sufficient heat. I found that I needed to reduce the target temperature on the heat pump controller. An air-to-air system can't match the comfort provided by a hot water system with its substantial thermal mass which retains warmth when the heat supply temporarily stops.

Posted by: @redguy17

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Hello Fellow heat pump/ sustainability fans.

 

I am trying to get my self the so called ‘holy trinity’ of Solar, Batteries and a heat pump.

I have had solar for 2 years now and love it. It’s a 5.5kw array with 6 panels facing south and three facing west. WE are pretty high users with daily averages of 10 kw plus. I’m looking to install 17 kw of battery storage to help tide us over in the winter months, charging up on the cheap rates on octopus go tariff.

I’ve been making enquiries for over six months and have been fobbed off by many installers who , I assume, are just to busy o be bothered to quote.

I’ve had two companies come over to do heat lost assessment and give me quotes for a heat pump. I wont name names but I had a you tube famous company come out to do a heat loss survey and before the guys even stepped into my house he was negative trying to dissuade me on cost grounds. My house is a typical 1950’s semi about 120 meters shared with 300 mm loft installation not wall insulation and is currently heated with a combi boiler and my wood burner.

Even though I have a normal garden he couldn’t find a single place to locate the heat pump that would fulfil his companies guidelines for heat pumps, not to mention that they only work with one supplier which means I could not wall mount as I had wanted and had to find a place in my garden.

The other company that came out is a local firm but they have designed the system to run at 65 degrees at -2 Celsius , not upgrade the rads and have a ‘ buffer’ tank. From my research these are red flags.

 

So unfortunately for me it seems I’m stuck between heat nerds who say computer says no and local cowboys who want to stick any old thing in. Has my heat pump journey ended what would you guys do ?

Thanks

Redguy 17

I wouldn't give up.  You presumably have cavity walls which either are, or could be, insulated and either double glazing or the potential to fit it.  With these done (which it would be best to do if not already done) its doubtful you need more than a 6kW heat pump and certainly not more than 8kW (unless where you live, which you don't say, is very cold).  There is a problem in that the industry tends to overestimate the capacity needed, which can make it impossible to find somewhere to fit the unit.  For comparison my house is 1930s solid wall with partial fabric upgrades, 200sq m, 7kW @ -2.  Two professional surveys, 3 hrs each, claimed 16kW which is complete baloney.  Admittedly this is probably an extreme case.

If, for example, you can find somewhere to put the '7kW' Vaillant heat pump, then that's almost certain to be sufficient given the fabric upgrades above.  The 11.2kW Mitsi isnt much bigger.  You may well be able to get away with something with significantly less capacity, which could also be quite a lot smaller and quieter.  

If you know your gas/oil consumption you can get a reasonable estimate of the requirement, if you have half hourly meter readings you can do even better by plotting daily consumption against average OAT.

There are installers out there who will think outside the box, but perhaps only 10-20% of the total.  You may need to find one of these.  First I would recommend you 'do yourself a favour' by collecting some more data and/or doing obvious fabric upgrades if they haven't been done.

@johnr Thanks for your pragmatic suggestions. I wish the 'Hot nerd' that came to do my assessment was thinking out side the box like this but I did find him very 'little britian' in his attitude. One issue he did highlight that I forgot to mention is that in order to qualify for the Boiler Upgrade Schme (BUS) that the whole property needs to be serviced by the repalcement heat pump therefore they could not do a partial system that takes in to account the wood burner or that I have an upstairs extention that has all new eletric heating. They need to design and install a whole house soultion only.

Has any one else had experince wit this and the BUS?

@jamespa Thanks foor your reply, I iwsh i could do cavity wall insulation but my wife is not convinced it will not be done poorly and make our house worthless. though this article refers to solid wall insulation itsw still ppuit the frighters on her https://www.bbc.co.uk/news/articles/c70kr365d8xo.

I'm hopeing i can find some one else who is willing to work with me to find a soultion that will allow me to have a more sutainable heating solution.

thanks again for your reply.

Posted by: @redguy17

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One issue he did highlight that I forgot to mention is that in order to qualify for the Boiler Upgrade Schme (BUS) that the whole property needs to be serviced by the repalcement heat pump therefore they could not do a partial system that takes in to account the wood burner or that I have an upstairs extention that has all new eletric heating. They need to design and install a whole house solution only.

Has any one else had experience wit this and the BUS?

He is correct this is written into the BUS rules.  Just to get a feel for what you need in terms of capacity:

• Whats your annual gas consumption, how old is the boiler?
• Whats the 'pattern' of heating (all day, evening only, evening and morning)?
• What proportion of the area does the electric heating cover?
• Do you use the wood burner every day or only from time to time?

@jamespa Hi james

my annual gas ussage is 26786 KwH( heating and hot water)

bolier is over 15 years old ( estimates 87% efficent)

i work at home so heat is on all day every day usually to 19 degrees

20% of the house ( a bed room and unsuite) are currectly heated with eletricity.

Currently dureing october to febuaury we use about 6 tonnes of wood as wood burner is on from 6 am till 6pm most days.