Air to Air Heat Pumps

Coldwarrior said:

Just on this about the PV solar again, I'm hopefully soon going to be moving to a new build (A2 or A3 BER) that'll have an air to water heat pump, underfloor heating downstairs and radiators upstairs. I'll be working from home most of the time and will probably go for an electric car the next time I change cars. The house won't come with any solar panels as standard, though I was considering asking the builder to install PV. From what you've said it sounds like it may not be worth it, is there any merit to installing PV in this case?

Click to expand...

The merits of installing PV panels are the same whether you have a heat pump or not to be honest. The point _OkGo_ is making is that PV will not be generating electricity at the times your heat pump needs electricity, so putting up PV thinking it will provide free electricity to run your heatpump does not make sense.

So you just need to look at your electricity usage and ignore whether there is a heatpump there or not and see if PV makes sense. The conclusion you'll likely come to is that it has a payback of somewhere between 6-10 years depending on whether you go for a battery or not and assuming you get a good price. If you plan to stay in the new house for 10/15/20 years then that payback period is fine and you'll be saving a decent few quid on electricity bills.

dem_syhp said:

Yes, sorry, photovoltaic panels, so yes, I'd absolutely expect costs to be lower in the summer (hence the comment, I can't really say for another 6 months how things will fare).

We still have a gas for cooking, albeit very low energy usage, but still have standing charges. [I know we can change, but for now things are staying as they are]

Yes, I agree we've someone in the house all the time, which wasn't the case a year ago, so I can't compare like with like. But I've no reference to how much other peoples bills have gone up with someone working from home.

Our yearly gas bill before, for heating + hot water, was about 500 Euro, this is based on the last two years - This was without shopping around as our figures were low, and shame to say on askaboutmoney I just didn't. But our most recent electricity bill (for two months) was in excess of 220 Euro (Estimated reading, but I'd the actual kWh used for the billing period month and just calc'd out difference). I didn't really expect our bills to go down, but hadn't expected it to go up....which by the time I've included summer it may not. I can only go on the data I currently have.

As has been suggested behavioral change is part of the problem....but its not one we want to make. (lack of research on our part before). How we previously liked to live is to turn on the heating when we were cold. So if actively working around the house - say working out, DIY, cleaning, moving around that is, I'd rarely need much/any heat. If sitting down, on the computer, in front of the television, I want a warmer room. I don't want a warmer room all the time - but that's how the set up is designed to run -I know its bad practice to be messing with it, so I don't..... but it doesn't suit me (yet! Maybe I'll go all soft and will want the additional heat ).

I'm not saying they're not efficient, I'm saying, so far, based on 4-6 months, the jury is out as to which way I'd go if given the choice again. The house is way more comfortable, we absolutely had rooms that were never comfortable, but that's the insulation.

Click to expand...

Whats your current views on heat pumps given you have 12 months experience?

Jazz01 said:

@Anniekate
From my understanding, unless your home is air tight, the air to heat pump wouldn't be recommended as a means to heat the home. Maybe as part of the retrofit you are doing, they will be performing this air-tightness? It's difficult to do in existing houses, but I guess not impossible.

The installation of all that insulation needs to be coupled with allowing enough ventilation flow in through the house and out again, so there will need to be a mechanical ventilation system running too.

All this costs money, so depending on your budget, it may / may not be feasible to implement everything. I recently saw on a RTE program (think it was EcoEye?) of a deep retrofit performed on a home, where the costings came to ~ €75K in total, then the applicable grants brought it down to around €50K. The owner did not go through in detail what was done, but at a high level, was the external insulation, new windows, doors, attic insulation and the air-to-heat system. Brought the house to an A rating (A2 or A3 I think).

(The air to water heat system I have in my own home is a Daikin system, double fan - think you were asking about the types in a different thread)

Click to expand...

That is the contradiction, we have vents in the walls and windows etc to prevent condensation and mold and we are told not to have leaks to run a heat pump

roker said:

That is the contradiction, we have vents in the walls and windows etc to prevent condensation and mold and we are told not to have leaks to run a heat pump

Click to expand...

Thats why you put in a proper heat recovery ventilation and stop using those dreadful holes in walls.

It’s not as simple as taking out your oil or gas boiler and installing a heat pump, you’ve got to do some upgrades to make the house more efficient nd in some cases the cost outweighs the benefit. You are better off getting a new more efficient oil or gas boiler

Clonback said:

Whats your current views on heat pumps given you have 12 months experience?

Click to expand...

Our usage of electricity has gone from approx. 1000kw per annum, to 2000kw per annum. We have solar panels, so the real usage has probably gone up to 2800kw per annum. This is for a two person, 3 bed room terraced house. Previously we both worked outside of the house, but now there is someone working from home all the time so not comparing like with like. We previously would have used approx 5kw of gas in addition to the electricity (price per kw for gas far lower than electricity and not comparable). My numbers aren't perfect, the previous ones are based off averages (but these' tended to be correct, rarely a big change when I did a reading. Current numbers are based off summer and winter averages - not exact. We still have a gas bill as we use it for cooking, although, clearly our usage is far lower, but we still have all of the standing charges and usage of approx. 600kW per annum - 9m cubed * conversion factor * 6 bills (I've based this off the last 4 months, but they're winter when we'd use the oven a bit more. )

We did a full retrofit, insulation windows, walls - the house is far more comfortable. But the house would be far more comfortable if we'd done all of the upgrades without the heat pump - but that's not how the grant worked.

We naturally prefer to keep a cooler house - 16 to 18 degrees. A notable amount of the energy we've used has been over night when temperatures are low to prevent it freezing. Maybe comparing bills for someone who keeps a house warmer there would be a more noticeable difference.

We didn't do the upgrade for cost savings - our bills were always low, but front of the house wasn't comfortable, even with the heating on (even as people that don't mind a cooler room). It was to future proof the house and make the front rooms usable - we're pleased we did that. But if I wasn't doing a full upgrade, upgrading the heat pump would be the very very very last thing I'd do. I think that we need to move away from fossil fuels, I think we need to move away from Gas. But when I look at the operation mode for the month of Jan, the freeze stat was 18% of the time, and heating was 23.8%, with water at 4%. That minimum level of having everything off, with a heat pump, is quite high in the winter time. Where as from now till November it will hardly kick in at all.

In hind sight we should have put more panels up (We went with what was recommended, I didn't think we could put more, I think we could have). Moving to electricity for cooking is likely to happen for us, but just not sure when, and I may need to convince someone else to give up gas cooking. The difference in comfort in the house is huge from improvements in the insulation. I can't tell with the bills as we've someone home more now, so its probably just offset it.

dem_syhp said:

[…] Moving to electricity for cooking is likely to happen for us, but just not sure when, and I may need to convince someone else to give up gas cooking. The difference in comfort in the house is huge from improvements in the insulation. I can't tell with the bills as we've someone home more now, so its probably just offset it.

Click to expand...

few years ago I installed both a gas hob and a induction hob. (Half/half so to say).
The gas one rarely gets used at all. Don’t think I’d bother with gas hob again, induction is great.

Are the controls for nduction hobs not very fiddly? I've only cooked on them a coupe of times, but the controls seemed to be very finicky, sometimes not responding to touch for example. I prefer the look of induction hob over gas, but love the simplicity and visual of gas.

newirishman said:

few years ago I installed both a gas hob and a induction hob. (Half/half so to say).
The gas one rarely gets used at all. Don’t think I’d bother with gas hob again, induction is great.

Click to expand...

I'd be the complete opposite

noproblem said:

For the pump to be totally efficient it's advisable to get your house or desired project technically assessed. In short, its air tightness, insulation, draughts, windows, chimneys (if any) etc. When people say it's costing them a fortune in electricity to run the heat pump I can assure you they didn't properly do their homework before going ahead with the work. Goosebump; This is a quickish answer to your query but very relevant.

Click to expand...

You are not making the system more efficient, you are making the house more efficient . So no matter what heating system you have you will save energy cost.
Correct me if I'm wrong but
the heat pump is running 3 motors, fan, compressor, circulating pump. All requiring energy