Air source heat pumps

[Chz]

What do you mean by "take air from inside the house"?

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.

 

[two sheds]

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.

I think teuchter was just questioning my phrasing.

Doesn't WouldBe's point come in then that I'm just pulling cold air into the house?

In which case doesn't my point come in that it's a sort of displacement ventilation?

 

[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.

 

[two sheds]

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.

 

[two sheds]

It's an air to air heat pump if that helps. I'm presuming they blow the air across the heating and cooling sides of the heat exchanger. And yes I'm not sure about the 'excess heat' bit, that would be the case for an air conditioner.

 

[lazythursday]

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.

 

[two sheds]

Do you switch off during the peak-cost electricity hours?

And presumably your place is well insulated.

 

[lazythursday]

Do you switch off during the peak-cost electricity hours?

And presumably your place is well insulated.

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]

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]

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.

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.

 

[two sheds]

Interesting, ta. Might be worth looking at Sempatap style insulating wallpaper just for that wall? I wondered about aerogel for stairs because they're narrow, too, but phenomenally expensive.

 

[lazythursday]

Interesting, ta. Might be worth looking at Sempatap style insulating wallpaper just for that wall? I wondered about aerogel for stairs because they're narrow, too, but phenomenally expensive.

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]

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]

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!

 

[two sheds]

Yep can imagine - possibly worth doing all the external walls. My place was bitter in winter so it's all really repaid well but I suppose with heat pump ironically you get longer repayment times.

 

[lazythursday]

Yep can imagine - possibly worth doing all the external walls. My place was bitter in winter so it's all really repaid well but I suppose with heat pump ironically you get longer repayment times.

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]

no one ever thinks about the repayment period for a gas boiler.

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