Renewable heat systems
Discussion
I purchased a house with a air source heat pump, it was sold as a positive and even that i'd earn money from it. Great.
It's taken 4 months to register it, and it turns out I will get £99/quater. But, I get charged £100/month eletric bill to run the thing. It's also started playing up, so a service is £500, which is yearly. It also only heats to 55degrees on a good day, so my house is never that hot and we drain the tank with just a bath.
The previous owners installed it, we don't get gas, at a cost of about £15k.
I'm struggling to see what the benifit is to these things!
(I've tried 4 of the 'approved suppliers' as well, and 3 no longer do it and 1 won't answer!)
It's taken 4 months to register it, and it turns out I will get £99/quater. But, I get charged £100/month eletric bill to run the thing. It's also started playing up, so a service is £500, which is yearly. It also only heats to 55degrees on a good day, so my house is never that hot and we drain the tank with just a bath.
The previous owners installed it, we don't get gas, at a cost of about £15k.
I'm struggling to see what the benifit is to these things!
(I've tried 4 of the 'approved suppliers' as well, and 3 no longer do it and 1 won't answer!)
I looked at all the alternatives ( not on mains gas ) and went, shock horror for electric radiators. They work really well, and the heating bills so far are very low. I did make sure when I built the house though that it was well insulated. They aren't storage heaters to be clear, just nice vintage style wall mounted electric rads.
I've looked at all the alternatives and factoring in costs and maintenance none of them have paybacks that would make me take the risk/hassle of using them.
I've looked at all the alternatives and factoring in costs and maintenance none of them have paybacks that would make me take the risk/hassle of using them.
If you are going for an ASHP it isn't just a "bolt on" to the system - you need the hot water heated by an immersion heater if you can't get it above about 65 degrees, and the rads need replaced with higher output ones to make up for the lower flow temperatures.
Ideally these are put in as part of a new build, not a retrofit - they are perfect for underfloor heating, and if gas is available, instantaneous gas hot water heaters are great.
What brand is it, by the way?
Ideally these are put in as part of a new build, not a retrofit - they are perfect for underfloor heating, and if gas is available, instantaneous gas hot water heaters are great.
What brand is it, by the way?
The house is very old, with an extension. The system was put in when the extension was done, as well as the rads. But I highly doubt they are special rads, knowing how cheaply everything was done. (How does one tell? they look standard)
We do have an immersion, although I've never seen the water temp up to 65.
No gas, hence this system. It's a Mitsubishi.
We do have an immersion, although I've never seen the water temp up to 65.
No gas, hence this system. It's a Mitsubishi.
They wouldn't look "different", just larger or doubled up - a double panel, double convector radiator as opposed to a single panel, single convector, for instance. Or just physically bigger.
You might also have problems with the ASHP as the weather gets colder - a couple of years ago we had a stack of them just keep cycling - they'd freeze up, bring on their electric heating coil to defrost, then start working, then freeze up, etc.
Modern ones are better in this regard, and more efficient, but I'd still be reluctant to spec one for the highlands of Scotland or somewhere unless it was seasonal use only!
Mitsubishi do a good system nowadays, most manufacturers are starting to make them more efficient and less prone to freezing up.
You might also have problems with the ASHP as the weather gets colder - a couple of years ago we had a stack of them just keep cycling - they'd freeze up, bring on their electric heating coil to defrost, then start working, then freeze up, etc.
Modern ones are better in this regard, and more efficient, but I'd still be reluctant to spec one for the highlands of Scotland or somewhere unless it was seasonal use only!
Mitsubishi do a good system nowadays, most manufacturers are starting to make them more efficient and less prone to freezing up.
We're not on main s gas and didn't have heating. Looked at various options and settled with biomass. We did go done the air source option for a while but the potential freezing issues came to light and they happen when its the coldest and you need the heat the most so was then discounted.
Its a 350 year old house. single glazed with minimal internal insulation (at the moment). Biomass unit cost us £20k to install and its been great - bonus is that our electric bill has reduced by £600pa (no dehumidifiers required and water was heated with electric previously and now heated by the biomass) and we'll get approx. double our initial outlay back off the government over 7 years.
FFG
Its a 350 year old house. single glazed with minimal internal insulation (at the moment). Biomass unit cost us £20k to install and its been great - bonus is that our electric bill has reduced by £600pa (no dehumidifiers required and water was heated with electric previously and now heated by the biomass) and we'll get approx. double our initial outlay back off the government over 7 years.
FFG
FlipFlopGriff said:
Biomass unit cost us £20k to install and its been great - bonus is that our electric bill has reduced by £600pa (no dehumidifiers required and water was heated with electric previously and now heated by the biomass) and we'll get approx. double our initial outlay back off the government over 7 years.
FFG
Hmmm, what's it run on?FFG
Correct me if I'm wrong, but a quick google without even delving into the catalogues shows that as a 5kW unit? That might do one room, certainly not a whole house - and if you are trying to heat the whole house with it, it'll freeze at the drop of a hat and spend about 90% of it's time that way! Tell me it's a typo?
illmonkey said:
It's a PUHZ-W50VHA. Boiler? I don't have a boiler. I have the PUHZ-W50VHA and a hot water tank.
Think the tank is 190l.
Think the tank is 190l.
I don't think it's comparable to say a log burner. Mitsubishi seem to think it's fine for a new build. (maybe not my 300 year old house though).
https://heating.mitsubishielectric.co.uk/Products/...
https://heating.mitsubishielectric.co.uk/Products/...
Certainly not for your 300 year old house! A newbuild needs around 50w/m2 for heat, so say a smallish 3 bed semi might get away with 5kW. I'd triple that for an older house, 1920s or so, and even more if it's 300 years old and not hugely over-insulated - what size is the place?
And the 5kW rating is for a 35 degree flow temperature, normal boilers have a 82/71 flow/return temperature - your radiators would need to be massive. I'd start by isolating the HW cylinder and trying it on just the rads, but I think that HP is horribly undersized...
And the 5kW rating is for a 35 degree flow temperature, normal boilers have a 82/71 flow/return temperature - your radiators would need to be massive. I'd start by isolating the HW cylinder and trying it on just the rads, but I think that HP is horribly undersized...
illmonkey said:
I don't think it's comparable to say a log burner. Mitsubishi seem to think it's fine for a new build. (maybe not my 300 year old house though).
https://heating.mitsubishielectric.co.uk/Products/...
https://heating.mitsubishielectric.co.uk/Products/...
87sqM, over 3 floors. Basically a 2up2down with a basement.
Front half is old, with secondary glasing. Ground floor is semi detached, 1st floor is terraced (flying freehold over an archway) not a cavity wall. Rear half is the new build, double glasing, cavity wall. Some of the rad are about 2meters wide, usual height.
By what you say, I need a 13KW HP.
Front half is old, with secondary glasing. Ground floor is semi detached, 1st floor is terraced (flying freehold over an archway) not a cavity wall. Rear half is the new build, double glasing, cavity wall. Some of the rad are about 2meters wide, usual height.
By what you say, I need a 13KW HP.
That's what I'd aim for - and remember the harder you drive it, the more likely it is to freeze up. I have a project going at the minute that'll be using two Vaillant Arotherm 15kW units in parallel (half way up a bloody mountain!) - you're probably looking at about £5k for one of those. Easy to fit yourself, if you are handy (and your piping is already there!)
We spec two rather than a larger unit to allow forredundancy should one die off. The actual heat load will be around 15kW anyway, but by installing them so they'll only be running at half power, they won't freeze up.
Manufacturers talk a load of s
t about the minimum temps their pumps can run at - minus 15 degrees? Aye, maybe, if you're only trying to get 1 kW out of a 10kW unit!
You just can't spec them like you can boilers, where they can run in freezing temperatures pretty much until they run out of gas or oil!
We spec two rather than a larger unit to allow forredundancy should one die off. The actual heat load will be around 15kW anyway, but by installing them so they'll only be running at half power, they won't freeze up.
Manufacturers talk a load of s
t about the minimum temps their pumps can run at - minus 15 degrees? Aye, maybe, if you're only trying to get 1 kW out of a 10kW unit!You just can't spec them like you can boilers, where they can run in freezing temperatures pretty much until they run out of gas or oil!
Well, thats all good and well, but I'm less than impressed with the whole thing anyway, so I'm unlikely to drop £5k on a new HP!
We've got a fire and it's not been too bad the last few weeks (we've seen -6, I doubt we'll get much colder than that).
I just want the damn thing to run consistantly, if that means dropping the temp and having it on for longer so be it. The main issue is it doesn't want to swap from hot water to heating.
The error code I get is U1, which is something to do with pressure, I'm hoping it just needs topping up or something.
We've got a fire and it's not been too bad the last few weeks (we've seen -6, I doubt we'll get much colder than that).
I just want the damn thing to run consistantly, if that means dropping the temp and having it on for longer so be it. The main issue is it doesn't want to swap from hot water to heating.
The error code I get is U1, which is something to do with pressure, I'm hoping it just needs topping up or something.
Aye, it's a ball-ache, but you can always throw in an oil boiler and use the ASHP to heat part of the house! The U1 fault is overpressure normally on mitsi units - it could be that your fan has clogged up, died, or the condenser is blocked... with ice or summat! Too many possibilities to diagnose it over the net really.
illmonkey said:
Well, thats all good and well, but I'm less than impressed with the whole thing anyway, so I'm unlikely to drop £5k on a new HP!
We've got a fire and it's not been too bad the last few weeks (we've seen -6, I doubt we'll get much colder than that).
I just want the damn thing to run consistantly, if that means dropping the temp and having it on for longer so be it. The main issue is it doesn't want to swap from hot water to heating.
The error code I get is U1, which is something to do with pressure, I'm hoping it just needs topping up or something.
We've got a fire and it's not been too bad the last few weeks (we've seen -6, I doubt we'll get much colder than that).
I just want the damn thing to run consistantly, if that means dropping the temp and having it on for longer so be it. The main issue is it doesn't want to swap from hot water to heating.
The error code I get is U1, which is something to do with pressure, I'm hoping it just needs topping up or something.
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