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Re: Air to Air : Air Source Heating

Posted: July 12th, 2021, 9:15 am
by richlist
This thread is about air to air heating not air to water.

Re: Air to Air : Air Source Heating

Posted: July 12th, 2021, 11:39 am
by Mike4
Spritehawk wrote:
We didn't have gas to the house, so a gas boiler wasn't an option and we were previously heating with oil-filled radiators. The biggest shock for me was that our heating costs didn't seem to reduce with the ASHP.

And
But all in all, I am pleased with it. It's nice to have the house at a constant temperature and I can kid myself I'm doing my bit for the planet.


If your electricity bill has not dropped, might this be because your heat pump is burning the same amount of electricity as the oil-filled rads before?

And if there is no reduction in electricity consumed, it seems to me the whole exercise was pointless and yes you ARE kidding yourself!

I think there is probably something wrong with your installation that needs identifying and fixing.

Re: Air to Air : Air Source Heating

Posted: July 12th, 2021, 12:17 pm
by Mike4
ReallyVeryFoolish wrote:
Mike4 wrote:
Spritehawk wrote:
We didn't have gas to the house, so a gas boiler wasn't an option and we were previously heating with oil-filled radiators. The biggest shock for me was that our heating costs didn't seem to reduce with the ASHP.

And
But all in all, I am pleased with it. It's nice to have the house at a constant temperature and I can kid myself I'm doing my bit for the planet.


If your electricity bill has not dropped, might this be because your heat pump is burning the same amount of electricity as the oil-filled rads before?

And if there is no reduction in electricity consumed, it seems to me the whole exercise was pointless and yes you ARE kidding yourself!

I think there is probably something wrong with your installation that needs identifying and fixing.

An alternative explanation might be that the entire house is more comfortable. So, burning the same kw of electricity as before but keeping the house more comfortable to live in. Not an entirely unsatisfactory outcome?

RVF


True, but if the heat pump is truly running at 300% efficiency compared to the 100% of the oil-filled rads, that would result in one helluva rise in 'comfort'!

And agreed, burning the same amount of leccy as before is not "entirely unsatisfactory" but from an environmental POV there has been no improvement, which was the main point of the exercise surely.

Re: Air to Air : Air Source Heating

Posted: July 12th, 2021, 2:34 pm
by Spritehawk
When we were using the oil-filled radiators, we had them on timers to be on when we were at home during the day, and off all night. Now, with the ASHP, the heating runs as needed to keep the house at the same temperature. That's how they work - they don't have the output to heat the house up from, say 15 degrees to 20 degrees in a couple of hours as a conventional system would. As I say, I am disappointed that I'm not saving on electricity (although I'm going off bills paid - not KWH used, as I've not had it a year yet so can't compare like for like and the cost of leccy has gone up in the meantime).

Roughly speaking, I'm paying about the same as I was, but for a more comfortable house and I'm not burning fossil fuel and giving off greenhouse gases. As electricity becomes more from renewable sources (and my next move is probably solar panels) I will have less impact on the environment, but to be brutally honest, that was not my main driver in choosing this system. It was mainly that I see gas being phased out and I didn't want to invest in an obsolete technology, and neither did I want to have an oil tank installed and have to keep monitoring the level, etc.

Whatever I did, it was going to be a significant financial outlay and at least the ASHP had a grant attached. For me that part of the system came to about £8K - the radiators and piping were extra, but they would have been needed whatever the system.

You pays your money and you takes your choice. It's cleaner than gas (but more expensive to run) but hasn't significantly reduced my electricity bill. I'll be able to confirm the annual useage in KWH in October.

Re: Air to Air : Air Source Heating

Posted: July 12th, 2021, 2:38 pm
by Spritehawk
Mike4 wrote:
ReallyVeryFoolish wrote:
Mike4 wrote:And


If your electricity bill has not dropped, might this be because your heat pump is burning the same amount of electricity as the oil-filled rads before?

And if there is no reduction in electricity consumed, it seems to me the whole exercise was pointless and yes you ARE kidding yourself!


And agreed, burning the same amount of leccy as before is not "entirely unsatisfactory" but from an environmental POV there has been no improvement, which was the main point of the exercise surely.



No - the 'point of the exercise' was to install a central heating system. We didn't have one previously - it was a matter of which system to go for. I did thing it would reduce the leccy useage and cost, but I knew it wouldn't get down to the pricing of a gas system.

Re: Air to Air : Air Source Heating

Posted: July 12th, 2021, 2:49 pm
by Mike4
Spritehawk wrote:
Mike4 wrote:
ReallyVeryFoolish wrote:



No - the 'point of the exercise' was to install a central heating system. We didn't have one previously - it was a matter of which system to go for. I did thing it would reduce the leccy useage and cost, but I knew it wouldn't get down to the pricing of a gas system.


Apologies, I misunderstood. I thought you already had satisfactory heating and did it for environmental reasons.

If what you actually achieved was vastly improved heating performance at no extra leccy consumption, I agree this is a big win!!

Re: Air to Air : Air Source Heating

Posted: July 13th, 2021, 8:15 am
by Nimrod103
Spritehawk wrote: and I'm not burning fossil fuel and giving off greenhouse gases.


As any person who has studied the Gridwatch graphs can work out, about 50% of the UK's electricity comes from burning gas (plus a small amount of coal). Indeed eyeballing the graphs for this year so far, compared to the same period last year, suggests that the wind contribution has been significantly lower this year compared to last.

Re: Air to Air : Air Source Heating

Posted: July 13th, 2021, 9:24 am
by Mike4
Nimrod103 wrote:
Spritehawk wrote: and I'm not burning fossil fuel and giving off greenhouse gases.


As any person who has studied the Gridwatch graphs can work out, about 50% of the UK's electricity comes from burning gas (plus a small amount of coal). Indeed eyeballing the graphs for this year so far, compared to the same period last year, suggests that the wind contribution has been significantly lower this year compared to last.


I find that most surprising, given we still have the same PM.

Re: Air to Air : Air Source Heating

Posted: July 20th, 2021, 12:58 pm
by Gan020
Spritehawk wrote:I had an air source heat pump installed last year and here are my thoughts.

But all in all, I am pleased with it. It's nice to have the house at a constant temperature and I can kid myself I'm doing my bit for the planet. To be honest, if we'd had a gas supply I would probably have gone with the easy option of getting a gas central heating system, but I'm happy with what we've got. Just don't expect a big drop in your electricity bill!


I've had a ASHP for 10 years now and my spreadhseet shows my heating costs have dropped dramatically.

A couple of things to point out:
1. I am a little unsure about the economics of running it 24 hours a day as trickle heat as there's the electricity cost of running the circulation pumps constantly. I worked this out once and it is not inconsiderable. I do not run mine overnight.
2. When I installed energy efficient light bulbs my heat pump had to work harder. It's surprising just how much heat those old light bulbs used to put out. (so, I'm not sure installing these light bulbs actually saved me)
3. I do have solar PV and solar thermal too. In Oct and Mar this helps alot as a lump of the energy cost for the ASHP is for free
4. I find once the temperature drops below around -3c for days on end my ASHP struggles and I become aware of the noise.

Re: Air to Air : Air Source Heating

Posted: July 21st, 2021, 4:11 pm
by bungeejumper
Gan020 wrote:1. I am a little unsure about the economics of running it 24 hours a day as trickle heat as there's the electricity cost of running the circulation pumps constantly. I worked this out once and it is not inconsiderable. I do not run mine overnight.

Are you talking about the actual ASHP unit's needs here, or about the CH pump that drives the radiator system inside the house? I don't have an ASHP (yet....), but my fairly meaty Grundfos CH pump (15/60) is drawing only 22 watts on a mid speed setting. Which would be around half a kilowatt hour per day, which would be on the right side of 10p. ;)

Agree with an earlier poster, though, that the noise from ASHP units is a potential nuisance, although probably for the owner's neighbours rather than the owner himself. A friend has just installed one in a quiet deep-rural location, and it's surprising how far those 42/60 decibels can carry. At night, it's as though his neighbour had left his car's engine permanently ticking over on the drive. Hmmmm.

Still, they're getting better (and more efficient, and quieter) at an impressive rate these days, so give it another five years and we 'll take another look.

BJ

Re: Air to Air : Air Source Heating

Posted: July 21st, 2021, 4:44 pm
by Gan020
bungeejumper wrote:
Gan020 wrote:1. I am a little unsure about the economics of running it 24 hours a day as trickle heat as there's the electricity cost of running the circulation pumps constantly. I worked this out once and it is not inconsiderable. I do not run mine overnight.

Are you talking about the actual ASHP unit's needs here, or about the CH pump that drives the radiator system inside the house? I don't have an ASHP (yet....), but my fairly meaty Grundfos CH pump (15/60) is drawing only 22 watts on a mid speed setting. Which would be around half a kilowatt hour per day, which would be on the right side of 10p. ;)

BJ


Thanks for your reply. I'm talking about the circulation pumps that drive the water round the rads. My system has 2 circulation pumps because I assume one would not be sufficient to drive the water round. I shall have to have anohter think on this. I'm sure when I worked it out years ago the cost was much higher.

Re: Air to Air : Air Source Heating

Posted: July 21st, 2021, 6:24 pm
by mao44
We have been using a Daikin air con unit for over a decade and very rarely use it for cold air as we rarely get too much hot weather for longer than a few days. However, we use it regularly from November until April for heat and it helps take the strain off our gas central heating system and saves too much wear and tear on the boiler which we have had for 13 years now. We live in the south west so it rarely drops below zero in the winter and the Daikin works well. When it's running, we turn the gas thermostat down to zero. When we had a smart meter, it showed that the Daikin cost around 5p an hour to run, so very cheap.

Re: Air to Air : Air Source Heating

Posted: July 21st, 2021, 9:53 pm
by fisher
Gan020 wrote:I'm talking about the circulation pumps that drive the water round the rads. My system has 2 circulation pumps because I assume one would not be sufficient to drive the water round. I shall have to have anohter think on this. I'm sure when I worked it out years ago the cost was much higher.


If you're system is plumbed similarly to mine, there are two pumps that have different jobs. One is known as a "charge pump" which circulates the water from the ASHP to a central heating buffer tank and then returns to the ASHP. The second pump circulates the water from the buffer tank, around the radiators and returns to the buffer tank. In my system the "charge" pump circuit can also be switched to circulate around the domestic hot water cylinder instead of the CH buffer tank. This allows the heating of the hot water cylinder while the central heating circuit is still circulating.