I'd rather they be used on my house than someone who's renting my house if that makes sense. This would be the 3rd house they've been on (only been here a year as it was a restoration project). First move was effortless and original installer came back out and reinstalled.
Heat Pumps: anyone have one/thought about it?
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I'd rather they be used on my house than someone who's renting my house if that makes sense. This would be the 3rd house they've been on (only been here a year as it was a restoration project). First move was effortless and original installer came back out and reinstalled.
Had my heat loss survey today by a local company.
The result, total heat loss at -3c 6998w, my Heatpunk survey I did came out at 6992w at -3.2c, so very close indeed.
His recommendation is to run at a 50c flow temperature as we have solar, and large batteries and thus very low electric costs, this will mean we don't need to replace any radiators. We can then experiment and I can replace radiators if I feel the need to. Doing this would be more cost effective than having them design at a lower temperature and changing loads of rads, it will still be a 7kW heat pump, so nothing to lose really in my mind. Heatpunk gives a SCOP of 3.65 at 50c flow, so still respectable.
He's also recommending a 250ltr tank, it will be tight but may fit where the existing boiler is, they may need to fit a small buffer / expansion vessel in the loft, or the cloakroom - it's just a coat and shoe cupboard basically, so can lose a little space from there - there is far too many womens shoes in there anyway!
They are going to quote for both a Vaillant aroTherm Plus 7kW & 250l Unistor pre-plumbed HWC and the Kronoterm 9kW Adapt with equivalent Hydro C2.
I've not heard of Kronoterm, anyone have any opinions or thoughts on the above as well?
The result, total heat loss at -3c 6998w, my Heatpunk survey I did came out at 6992w at -3.2c, so very close indeed.
His recommendation is to run at a 50c flow temperature as we have solar, and large batteries and thus very low electric costs, this will mean we don't need to replace any radiators. We can then experiment and I can replace radiators if I feel the need to. Doing this would be more cost effective than having them design at a lower temperature and changing loads of rads, it will still be a 7kW heat pump, so nothing to lose really in my mind. Heatpunk gives a SCOP of 3.65 at 50c flow, so still respectable.
He's also recommending a 250ltr tank, it will be tight but may fit where the existing boiler is, they may need to fit a small buffer / expansion vessel in the loft, or the cloakroom - it's just a coat and shoe cupboard basically, so can lose a little space from there - there is far too many womens shoes in there anyway!
They are going to quote for both a Vaillant aroTherm Plus 7kW & 250l Unistor pre-plumbed HWC and the Kronoterm 9kW Adapt with equivalent Hydro C2.
I've not heard of Kronoterm, anyone have any opinions or thoughts on the above as well?
Fair enough.
Given panels are so cheap now (e.g. £50 each) and the vast majority of the cost these days is the installation, I'd have thought you'd be better off just buying new panels than removing the old ones and re-installing them. Battery can be easily removed in a few minutes, the rest is a days labour for 2 people plus scaffolding and an electricians time to make the inverter circuit safe.
10 430w panels, mounting kit, 5.5kw hybrid inverter and all the sundry items you'd need to install is under £1900 (ex VAT but there is no VAT on a new install - not sure on a move - probably VATable).
Sounds like a good outcome, do it! In your scenario 50C is more than fine IMO, you've seen the stats I've posted so you know how cheap it can be and you'll be paying less than me thanks to your mega solar set up.
Vaillant is a very known quantity, well regarded and is will supported in the UK for what it is worth. The controls are also meant to be very good also.
I've not heard of Kronoterm either, on that basis I would go Vaillent.
The all important question, how much for just the install with no rads?
How much is the question, I shall find out next week, but it's not going to be cheap, There initial online estimate was : £7,700 - £9,300 after deduction of the grant, which is very expensive, I'm hoping it comes out significantly less. That didn't include extra rads or the heat pump base either.
Vaillant is my preference, they've been around for years and have a good support network, and good reputation.
Vaillant is my preference, they've been around for years and have a good support network, and good reputation.
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I did not know the price had come down so much. You've given me something to think about!
Maybe I'm missing something but if your heatloss is pretty much 7kw at -3, and you fit a 7kw heater, when you then have weather below -3 your house is slowly going to cool down? Would you not be better with something with a bit more margin for error.
Yes, sort of but in practice it’s fine.
Heat loss surveys air in the side of caution, that’s the maximum it should be, it’s likely less. This is one of the reasons it is really important not to oversize your heat pump.
We don’t get day time temperatures below that level, certainly not for any sustained period, particularly not where @Ron-ski lives.
It may drop below that level overnight for a couple of hours but you tend to have a lower target temperature overnight to aid sleeping anyway.
Heat loss is directly relative to the difference between the inside and outside temperature. So in the very unlikely event of it being -4c for a sustained period, the house would only drop 1C (assuming normal target is 21c).
Your house has a lot of thermal mass within its envelope and because you run them all the time, it’s all up to temperature and helps maintain that steady state temperature.
The thermal mass will start releasing heat if the house cools. Even if you had a very long sustained period of -4c, it would take a long time to cool down 1C as you are still inputting 7kw.
If you lived at the top of a hill in Scotland, you’d probably design it to a slightly lower temperature but not that much lower, probably -4.
Mines only designed to -2 but to the point in my second paragraph, my heat loss was over estimated by a decent chunk and I can get away with my flow temps as low as 41@-2 rather than the 50 design temperature.
That sounds crazy expensive to me. I'm looking at £600 all in from Octopus. I had the survey on Thurs and am just waiting for the report. That's with quite a few radiator replacements too by the looks.
I do know at least we won't be getting the Cosy 6, as the location doesn't allow it as there are vents nearby. It'll be the daikin.
Octopus price is such an outlier in the market. Independents simply can't match that and still make money.
E.g my Octopus quote was £4.5k and independents are between £9-£13k. Not a chance of this mass rollout the gov wants.
That said £8-9k for a 50c flow temp, that doesn't suggest the system is anything special, iirc that's the same temp Octopus usually design to.
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You raise a very valid point, but the 7kW aroTherm can generate 7.5kW of heat with flow temperature of 50c at outside temperature of -5c, rising to 9kW at +2c. At a lower flow it can generate even more heat, at 35c flow it generates 8.2 kW of heat at -5c, so it can actually generate more heat than the rating suggests.
Then you've got all of what @b0rn2sk8 said, its very rare it gets below freezing down here (south east England), lowest temperature we've recorded this winter is 0c. I've been following a guy in Scotland, his heat loss was just below 8kW, and that was taking into account yet to be fitted triple glazing. He had a 7kW aroTherm installed, and even with temperatures as low as -10c has not had a problem, and he's still got the old double glazing, and he has a lot of it.
Add to that I have a 5kW wood burning stove, and a big stack of dried wood for emergencies.
What you have to remember or realise, is that Octopus are installing these pretty much at cost or a loss, they have massive buying power, but I doubt very much they are making a profit on them. The quality of install will not be be so good, and I don't think they will do what I want.
The guy I mention in Scotland paid £12.5k after grant, if you knock off the cost of his extra radiators then it comes to £6.3k after the grant, that does include Open Energy Monitoring as well.
The Heatgeek I contacted hasn't come back to me, and is not replying to WhatsApp or answering the phone, so he's out of the running. I've got another couple of local installers to try, and I may give Octopus a go and see what they come up with, but I really want a Vaillant system, or Daiken as second option, and I want a compact install, and its this point I don't think Octopus will manage that, they are not very flexible.
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That's sort of what i was getting at. For the sum being asked, I would hope for a system that can do Iower flow temps. Octopus design for a relatively high 50C and options are limited, but as has been said, they're probably doing it at or close to cost.
Hopefully as time goes on prices will fall rapidly.
I'm after a compact install too, so I'll be interested what Octopus come back with. Essentially the whole lot will be in a 850 x 650 x 2200mm cupboard where the combi currently sits, with a few things in the loft above, so not a lot of space to work with. The surveyor thinks they can get a 210 litre slimline tank (475mm diameter) and the various bits in there no problem. I won't be convinced until I see the proposal though. From memory he suggested 9 radiator changes too, so if they can manage all that for only £600 cost to me I'll be impressed.
@reef I'll be very interested on what they come back with. My space is smaller though about 650 wide x 700 deep, probably around 2000mm high. It's where the current floor standing boiler fits. There is space to put some small stuff in the adjacent cloakroom though.