Chz
Stark Raving Sane
Think of a heat pump as an air conditioner in reverse. An AC unit will vent cold air into the room and hot air out. Swap the outputs, but still take the air from inside the room as input.
Air source heat pumps
- Thread starter WouldBe
- Start date
teuchter
je suis teuchter
The heat pump moves heat from outside to inside via a sealed refrigerant circuit doesn't it? So what are these air pipes actually there for? I don't see why they should be moving any air between inside and outside at all.
Also their description of the exhaust hose dumping "excess heat" outside doesn't seem to make any sense if the whole point is to increase heat inside.
I think I need to see a diagram.
Also their description of the exhaust hose dumping "excess heat" outside doesn't seem to make any sense if the whole point is to increase heat inside.
I think I need to see a diagram.
two sheds
Least noticed poster 2007
I'm also not sure how it works as a dehumidifier since it doesn't actually fill up the tank when being used like that (rather than heat pump or air conditioning unit). I thought for a while that it just wasn't working but now I wonder whether all the moisture gets expelled.
lazythursday
Averagely-Known Member
I now have over a week of actual data on how my new heat pump is performing.
Prior to installation, I had gas heating on to 18 degrees from 6am-9pm, with the odd boost upwards if I was feeling particularly cold. Now, I have heating 24 hours a day - 20 degrees 6am-9.30pm, 18 degrees the rest of the time. The only caveat to that is I've been told the Maduka room thermostats can overestimate, and I've not tested it, but it definitely feels significantly warmer than before.
Compared with the week prior to installation, my total energy costs (on same tariff as before) are a whopping 26% cheaper (from £50 to £36) and compared with the week before that, 19% cheaper. I have now switched to the Octopus Cosy tariff, which gives you three almost half price periods of electric and one expensive peak time, and based on the first two days of using that I will save an additional 13-14%.
This is a bit unexpected - my calculations before going ahead with this was that I would come out approximately the same in costs - or perhaps slightly cheaper, down entirely to the removal of the gas standing charge. Some of this is probably down to the age and inefficiency of the old system but I'm beyond impressed. And my energy usage has gone down from around 500 KwH to 135 - it's like pure voodoo.
Yes there's a learning curve, they are not a like-for-like replacement for a boiler. I'm still tinkering with the settings and the apps / control panel really need to be more consumer friendly (I think Octopus is doing this with its Cosy brand of heat pumps - mine's a Daikin, and they are not easy to understand). But so happy with it - just waiting to see how it copes with a proper cold, minus temperature day.
Prior to installation, I had gas heating on to 18 degrees from 6am-9pm, with the odd boost upwards if I was feeling particularly cold. Now, I have heating 24 hours a day - 20 degrees 6am-9.30pm, 18 degrees the rest of the time. The only caveat to that is I've been told the Maduka room thermostats can overestimate, and I've not tested it, but it definitely feels significantly warmer than before.
Compared with the week prior to installation, my total energy costs (on same tariff as before) are a whopping 26% cheaper (from £50 to £36) and compared with the week before that, 19% cheaper. I have now switched to the Octopus Cosy tariff, which gives you three almost half price periods of electric and one expensive peak time, and based on the first two days of using that I will save an additional 13-14%.
This is a bit unexpected - my calculations before going ahead with this was that I would come out approximately the same in costs - or perhaps slightly cheaper, down entirely to the removal of the gas standing charge. Some of this is probably down to the age and inefficiency of the old system but I'm beyond impressed. And my energy usage has gone down from around 500 KwH to 135 - it's like pure voodoo.
Yes there's a learning curve, they are not a like-for-like replacement for a boiler. I'm still tinkering with the settings and the apps / control panel really need to be more consumer friendly (I think Octopus is doing this with its Cosy brand of heat pumps - mine's a Daikin, and they are not easy to understand). But so happy with it - just waiting to see how it copes with a proper cold, minus temperature day.
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lazythursday
Averagely-Known Member
Have only been on the Cosy tariff a couple of days. The peak time is 4pm-7pm - I'm boosting up the temp slightly in the cheap hours before that (to 20.5) and setting it for 19 during 4-7. The heat pump tends to kick in again at about 6, so I am using it a bit during the peak time. Before switching, I used an app called Octopus Compare to analyse savings - and realised that even if I left the heat pump on without any amendments at all during the peak time I'd still save about 8% - the savings made by heating hot water in the very cheap time more than outweigh the extra peak time costs even without any load shifting.
It's partially insulated, and gradually improving. I have a reasonable level of loft insulation, and my upstairs has internal wall insulation. No cavity wall insulation because installers won't do it because of poor access. Quite old double glazing, and no insulation downstairs, which has quite a bit of heat loss through patio sliding doors etc. Basically when it's cold like now, if I turn the heating off I lose about a degree an hour, it doesn't hold the heat all that well.
two sheds
Least noticed poster 2007
What sort of internal insulation - plasterboard and battens? I can't get cavity wall insulation either because the walls are clay filled. The rooms are a bit small for battens and I fitted insulating wallpaper upstairs and down which was a decided improvement over just stone walls, but which I think is going to downgrade the house energy serstificate. I presume my portable heat pump isn't going to count because the rayburn's still connected up even though I don't use it.
lazythursday
Averagely-Known Member
Kingspan / battens / plasterboard. Losing about 8-9 cm from the relevant walls, and yeah it's annoying because they are already smallish rooms apart from one but it's not that noticeable. What's more difficult is my next bit - down the stairs. These are currently 800mm wide which seems to be the general standard - building regs luckily don't specify a width of stairs, but I am concerned they will feel a bit narrow afterwards. My builder mate has suggested using alububble instead to minimise width loss but given it will only save a few cm I'm not sure it's worth it.
house energy certificate - you mean EPC? - these are likely to change a lot soon anyway and will be calculated differently. I wouldn't have thought insulating wallpaper will downgrade anything. And at the moment heat pumps tend to downgrade your EPC because of the bonkers way the calculations are done.
lazythursday
Averagely-Known Member
I really should have looked into this more rather than just trusting my builder mate to get on with it, not come across either of those. Really wondering if I should bother with the stairs at all - I was going to finish this current phase of work after the upstairs was complete - and I now think the money might be better spent in improving the loft insulation further. But the stairs / hallway is now a wreck thanks to leaks caused when new bathroom was installed, and torn wallpaper from carrying stuff upstairs, so it really needs decorating and seems stupid to do so without insulating first... One thing just leads to another and more money spent...
two sheds
Least noticed poster 2007
Sempatap Thermal-5 metre x 1 metre - Reduces Heat Loss by 30% and saves on Fuel Bills
Sempatap Thermal is thermal insulation on a roll which is as simple and easy to apply as wallpaper and the benefits are remarkable.
www.mgcltd.co.uk
That's the stuff I used (although I had the original type which is breathable) on all my external walls. There are similar makes and it might be worth comparing with battens if you've sorted the water ingress, although insulation with battens give better results. It's really easy to put up - easier than wallpaper.
I looked at hemp insulation too and plasterboard/battens with sheep's wool which was tempting but more expensive. My main problem has been damp so I've painted throughout the house with a mould-resistant additive, seems fine so far but I don't suppose I'll be able to tell for a year or so.
I've gone a bit overboard with the dehumidifiers though, It's cured some floorboards which were buckling which was a nice surprise but I've had bits fall off my drop-leaf table and the floorboards seem to have shrunk so there's a bit of a gap along one side of the downstairs room. I'm hoping the joists haven't shrunk
lazythursday
Averagely-Known Member
Thankfully I don't have any damp in this house. I have spoken to my builder and am postponing my stairs while I investigate alternatives. To be honest the heat pump is doing so well any more insulation feels a bit pointless!
lazythursday
Averagely-Known Member
I'm not really thinking of the heat pump costs in that way, as the boiler needed replacing anyway, it was a similar cost, and no one ever thinks about the repayment period for a gas boiler.
I don't think the insulation will necessarily pay for itself while I live here, but there's a lot to be said for spending money while you have it to enable cheaper bills when you don't - as no guarantee I'd still have the money then
two sheds
Least noticed poster 2007
I would
aside from the fact there's no gas supply here and I've never liked the idea of having gas in the house.I meant repayment time of extra insulation though
teuchter
je suis teuchter
On the foil based stuff, I'm a little out of date on the latest options but there was a product that ended up getting withdrawn a few years back because the claims they were making couldn't be validated. I think there are now a variety of types some of which claim to be breathable.
When talking about breathability you have to be careful though...for example breathable in which direction. The aim in a damp old building may different from what you want in a new one.
I think one of the problems with the foil stuff is that it's only effective with air gaps on one or both sides. And once you add in these air gaps you end up back at an overall thickness that's no better than alternatives. If a builder was proposing it to me, I'd ask exactly what they are proposing to use, and then I'd look very carefully at the installation instructions and make sure the builder was going to install it in that way.
When talking about breathability you have to be careful though...for example breathable in which direction. The aim in a damp old building may different from what you want in a new one.
I think one of the problems with the foil stuff is that it's only effective with air gaps on one or both sides. And once you add in these air gaps you end up back at an overall thickness that's no better than alternatives. If a builder was proposing it to me, I'd ask exactly what they are proposing to use, and then I'd look very carefully at the installation instructions and make sure the builder was going to install it in that way.
teuchter
je suis teuchter
Not quite worked out what, exactly?
newme
Giant in Pastyland now
My bill is £500 for oil this year. Air source doesn't suit the house and would need £20-40k of changes then need the electric reheat for legionaries likely to cost more than the oil did.
With under floor heating and a good heat rating and solar plus preferably a battery it works great. We don't even need the heating 99.9% of the time so constant hest is useless to us with the windows open most of the year
I wanted an air source water heater as recommended by 6 plumbers/heating engineers if I was forced to. Of course not an option
With under floor heating and a good heat rating and solar plus preferably a battery it works great. We don't even need the heating 99.9% of the time so constant hest is useless to us with the windows open most of the year
I wanted an air source water heater as recommended by 6 plumbers/heating engineers if I was forced to. Of course not an option
lazythursday
Averagely-Known Member
I don't think the legionnaires thing is much of an issue. My system runs a legionnaires cycle once a week - and yeah it's a lot more expensive than the normal water heating that happens each night, but you don't even really need to run it that regularly I don't think.
newme
Giant in Pastyland now
I was told once a week was minimum requirement. With a air source water heater it achieves higher temps and suits us better. We need it for showers and washing up not heating. Also don't want oversized rads for nonreason and ducting all over (been in a council place before and that's cheaper)
lazythursday
Averagely-Known Member
My new standard heat pump happily heats water to 48 degrees every night - you need it higher than that? And my rads are virtually the same size, some a big fatter. Barely any difference much to my surprise.
newme
Giant in Pastyland now
They wanted to rip out every rad in the house and replace with ones 1.5 times the size. This was also some years ago (before the air source cut price incentive was removed) when they were saying the water would not be at anywhere near 48c, they said 30c then the electric boost. Plus having to drill through the wall and work around parrots that really could not be moved anywhere easily and frankly the same for every single room, they would need to remove 3/4 of our house to make the 'upgrades' mentioned. With absolutely no space to move anything to. Plus wfh just made it entirely useless. Water heater would work great as we don't care about the rads, just had to turn them off at 15c cos it was too hot elsewhere even with only 2 on by the thing we are trying to dry. Frankly solar would have been far more useful and way cheaper.
two sheds
Least noticed poster 2007
an insulating layer on a wall means the outside-facing side of the insulation is colder that it would be, which means water is more likely to condense (I think) which gives possibility for mould. I'm not sure why that doesn't happen with insulation on breathable walls.
lazythursday
Averagely-Known Member
Perhaps worth investigating again at some point now things have moved on a bit? And the renewable heating incentive is gone but you can get the new boiler upgrade grant.
WouldBe
Dislicksick
Should be over 60 to kill any bacteria.
