UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

bushyh

It's been a busy heatless(well nearly) and car less week (thank you garage, went in with minor problem came out with major!). It's only now I seem to have time to update you all.

The positives first, they turned up, the Calorex guy was excellent - knew his stuff though obviously being a bit cautious about what he was saying.

Got the pump working - easy I could have done that if I had known it was just a case of unscrewing the panel and pressing the button.

Radiators are higher spec than those in the other house same as mine with gas boiler

There is an electric booster no one had told me about but - it is manual and does not therefore come on automatically

There is some doubt when temp is cold whether pump is high enough wattage for size of house even with the booster

It was left that he would write report for builder, I would try booster.

So, first couple of days having heating back felt like the Bahamas and indeed Thursday as it was much milder I was turning rads down but that didn't last long and clearly it is just not coping. At 4.30pm it was 16C having been on since 5am (I switched the booster on about 6.30am) it costs an arm and a leg to run - £10 a day if it comes on at 5 and goes off at 9pm and to be honest at the moment I cannot see any advantages (other than environmental ones) over a gas boiler. The suggestion that I would need two pumps if this isn't big enough feels me with horror as already I find the noise irritating. So I guess come next week I will be speaking with the builder again.

richardc1983

bushyh wrote: »

It's been a busy heatless(well nearly) and car less week (thank you garage, went in with minor problem came out with major!). It's only now I seem to have time to update you all.

The positives first, they turned up, the Calorex guy was excellent - knew his stuff though obviously being a bit cautious about what he was saying.

Got the pump working - easy I could have done that if I had known it was just a case of unscrewing the panel and pressing the button.

Radiators are higher spec than those in the other house same as mine with gas boiler

There is an electric booster no one had told me about but - it is manual and does not therefore come on automatically

There is some doubt when temp is cold whether pump is high enough wattage for size of house even with the booster

It was left that he would write report for builder, I would try booster.

So, first couple of days having heating back felt like the Bahamas and indeed Thursday as it was much milder I was turning rads down but that didn't last long and clearly it is just not coping. At 4.30pm it was 16C having been on since 5am (I switched the booster on about 6.30am) it costs an arm and a leg to run - £10 a day if it comes on at 5 and goes off at 9pm and to be honest at the moment I cannot see any advantages (other than environmental ones) over a gas boiler. The suggestion that I would need two pumps if this isn't big enough feels me with horror as already I find the noise irritating. So I guess come next week I will be speaking with the builder again.

Glad things are moving along for you but use that booster with caution as it will cost a fortune which you are already finding out yourself. USE WITH CAUTION otherwise you will end up with a very high bill.

My heat pump costs £5 a day and thats with me being on a £1 meter so yours must be using loads.

Noise is certainly not an issue for me I cant hear the thing at all, what noise are you referring to, the noise of the outdoor unit? You shouldnt be able to hear it through double glazing maybe in summer when your doors are open but not in winter. Is it a Calorex system you have?

I can 100% say for sure now that the unit is not powerful enough to cope, you shouldnt be needing to use the booster heater, thats usually for the water tank to boost the temperature of that once a week. So really they should be coming back out, removing the outdoor unit you have and putting in a bigger outdoor unit, one that is suitably sized for your house.

Cardew

bushyh wrote: »

So, first couple of days having heating back felt like the Bahamas and indeed Thursday as it was much milder I was turning rads down but that didn't last long and clearly it is just not coping. At 4.30pm it was 16C having been on since 5am (I switched the booster on about 6.30am) it costs an arm and a leg to run - £10 a day if it comes on at 5 and goes off at 9pm and to be honest at the moment I cannot see any advantages (other than environmental ones) over a gas boiler. The suggestion that I would need two pumps if this isn't big enough feels me with horror as already I find the noise irritating. So I guess come next week I will be speaking with the builder again.

Frankly if gas is available it would be madness to specify a heat pump IMO. The RHI might modify that.

Again IMO there is far too much 'enthusiasm' for heat pumps on MSE from those who consider themselves 'pioneers' and some vested interests promoting the technology.

There is always a reluctance from those who have spent many thousands of pounds on a heat pump system, to admit shortcomings. However there is enough information from those renting, or posts as above, and elsewhere on the internet to demonstrate that many heat pump systems simply do not cope with cold weather.

Agreed you can argue that the specification is not correct, but they are installed by professionals.

The undoubted disadvantages are:

1. The higher the water temperature - the lower the efficiency(COP). So huge radiators or Underfloor heating is required and the system run at water temperatures around 35-40C for max efficiency.

2. The lower the outside temperature the lower the efficiency(COP)

3. With gas CH you can set the boiler to 80C+ and water that hot in radiators enable heating to come on, say, 30 minutes before it is required. With heat pumps you need the heating on all day to bring a house up to temperature.

4. Heat pumps need defrosting cycles at regular intervals.

Obviously if no gas is available then heat pumps become more viable but the installation costs are still huge.

Cardew

richardc1983 wrote: »

My heat pump costs £5 a day and thats with me being on a £1 meter so yours must be using loads.

However isn't your system air to air(no radiators - blowing warm air) in a flat; and does that £5 a day exclude hot water?

Air to air is just not acceptable for many people.

richardc1983

Cardew wrote: »

There is always a reluctance from those who have spent many thousands of pounds on a heat pump system, to admit shortcomings. However there is enough information from those renting, or posts as above, and elsewhere on the internet to demonstrate that many heat pump systems simply do not cope with cold weather.

I disagree Cardew get a decent manufacturer and they cope just fine.

-5C here now in Leeds and my house at 22C throughout. Took about 3 hours this morning to raise the house from 11C upto 20C, tonight I am going to turn the temps down to 16C so it doesnt drop too low.

They work just fine if you oversize the outdoor unit in the first place it can ramp down when it doesnt require the full duty and then when it comes to cold weather like this it has that extra power if it needs it.

My unit is rated down to -15C I only start losing duty when outdoor temps fall below -5C and then again the system is oversized to allow for it.

Forgot to mention defrost cycles are every 5 hours on my system, and this is just an oil return operation it hasnt detected ice on the coils, it just times a oil return cycle every 5 hours of compressor operation. The coil isnt iced up because the air is so cold and dry there is no moisture in the air to freeze on the coils. Its worse when its at about 0C as you have moisture in the air but at -4C the air is very dry.

richardc1983

Cardew wrote: »

However isn't your system air to air(no radiators - blowing warm air) in a flat; and does that £5 a day exclude hot water?

Air to air is just not acceptable for many people.

It is Cardew, I prefer air to air and yes that £5 a day doesnt include hot water but I am factoring in the fact that I am on a coin meter.

My outdoor unit is a 9kw unit, all three indoors are 3.5kw in heating so in this sort of weather the outdoor unit is going full pelt all day long using 2.5kw of electricity every hour.

I think the user above has a similar capacity outdoor unit so its a good comparison even if I dont have hot water as the outdoor unit whether providing heating or hot water still has the same output as mine (thereabouts). Just goes to show that the electric booster heater is the using lots of power.

rhubarbe

I'm wondering if Cardew is an Internet name for Ned Ludd. I'm sure he doesn't have a heat-pump. I expect he lives in an area where you can get mains gas and an ivory tower from which to pur scorn on those of us less fortunate than he in terms of heat source choices. He always bangs on about low temperature of water and how they won't work if you have an efficient icicle hanging from your nose.

Many of us who have bought a heat pump have done so because we have no gas. Now, I'd be the first to accept that if you have mains gas, without the RHI, you'd not gain much from having a heat pump. But, for those of us without the option of mains gas, a properly specified ASHP (air to air or air to water) from one of the large manufacturers, properly rated and properly installed, knocks spots off oil, storage heaters, a large roaring log fire or even a small thermo-nuclear device in the back garden.

It's -5C here tonight (Cheshire), it's 22C inside, our pump is air to water, Ecodan, 8.5kW in a 1933 detached bungalow, and it costs us an absolute maximum of forty quid a week for ALL our electricity usage. Our background electric load, non-heat related is eight quid a week, so the math is simple.

We used to spend a fortune in coal (£16 a bag), LPG (God alone knows by now, I'd prefer not to enquire) and four tonnes of logs a year.

We had a look at a new oil system but it didn't work out any cheaper to install than the ASHP (with grants available), and I costed it with oil at 30ppl, not the 46ppl it is now.

I say, get a good installer, use a proper heat pump - not one of these Micky Mouse ones you can buy on eBay, get a proper survey, install in a fully insulated house and, if you're off the gas main, you'll never ever consider anything else again.

We've never had to use our booster switch yet.

richardc1983

Good post Rhubarbe.

How big is your house? I do miss having a proper fire to sit in front of though, however I may get one of those flame effect fires that you can put in place of the gas one theres something about sitting in front of flames.

What do you heat your house to during the night Rhubarbe and are you expecting electricity usage to go up during the cold spell, if so by how much each day?

Quiet_Life

May I ask a very basic question?

The heat pump that you are discussing, is it also known as a heat exchange system?

I ask because I have a relative that lives in Norway who keeps advising me to install a heat exchange system as it is much more efficient and cheaper to run, although most houses in Norway have excellent insulation.

richardc1983

Quiet_Life wrote: »

May I ask a very basic question?

The heat pump that you are discussing, is it also known as a heat exchange system?

I ask because I have a relative that lives in Norway who keeps advising me to install a heat exchange system as it is much more efficient and cheaper to run, although most houses in Norway have excellent insulation.

There are heat exchangers involved. Its likely that your friend is referring to a heat pump.

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