Air source heat pumps - any advice/experience?

[Clere3]

Hi All,

Just bought a house which has no central heating (brrr!) we're not on mains gas, so looking at oil boilers or air source heat pump as the two options.

We'll have underfloor or skirting radiators fitted throughout, which I believe should work well with air source heat pumps, but the technology is relatively new and I wondered if anyone had an experience?

Thanks

 

[Biggles..]

Have a look for a guy called Eaton on the forum (Kev f) he'll be your man for oil or air source.

 

[Kev F]

Hello, my names Kev Fisk of K Fisk Plumbing, best thing to do is give me a call on (........see.........profile ........ MOD) , I have an air source pump running my house and use it as a test unit to show people that want to view an actual system, your welcome to pop over and have a look and further chat, also oil is no problem but once you've done the maths with the government grants there won't be a lot in regarding install price.

 

[Norcon]

Hello, my names Kev Fisk of K Fisk Plumbing, best thing to do is give me a call ......., I have an air source pump running my house and use it as a test unit to show people that want to view an actual system, your welcome to pop over and have a look and further chat, also oil is no problem but once you've done the maths with the government grants there won't be a lot in regarding install price.

On UFH? Is your home super insulated? What size is the floor space?
How many kilowatts?

What is your yearly running cost? Have you an energy meter fitted?
Do you still have a fossil fuelled boiler fitted and use it as back up when its -10 outside? (Bivalent?)
Some numbers would help the OP I think.

This winter has been mild so far!
When you subtract the grants and subsidies I don't think they are very viable.

 

[dcawkwell]

12kW heat pump running at my house right now.
It ain't doing it! It struggles to heat half my radiators (about 6) to anything over about 40-45 degrees.
Good job I have my lpg boiler to cut in as a booster.

If you have reasonable insulation and double glazing an air source will do some of the year but wouldn't consider one as the sole heat source of the house especially once temperature start to drop below about 10 degrees outside.

I also have 3 air con units and they work wonderfully to heat the rooms or cool them down. These begin to struggle as the temperature gets to
zero in heating mode.

 

[Corgigrouch]

12kW heat pump running at my house right now.
It ain't doing it! It struggles to heat half my radiators (about 6) to anything over about 40-45 degrees.
Good job I have my lpg boiler to cut in as a booster.

If you have reasonable insulation and double glazing an air source will do some of the year but wouldn't consider one as the sole heat source of the house especially once temperature start to drop below about 10 degrees outside.

I also have 3 air con units and they work wonderfully to heat the rooms or cool them down. These begin to struggle as the temperature gets to
zero in heating mode.

I think that you need to speak to your installer as he has gotten something badly wrong..

My home isn't suitable for air to water without major alterations... Decent quality units work well in lower temperatures but can struggle in cold humid conditions so only a fool would try to install airsource without a reliable back up for those days...It was true 25 years ago when I first got involved in reverse cycle heat pumps and is still true today.

 

[Norcon]

"as he has gotten something badly wrong.."

I'd say nothing wrong. Its just the nature of the beast.

25 years and no progress doesn't bode well for the technology.

The manufacturers took an air source unit and added a £150 plate heat exchanger and a few other cheap gubbins and then added nearly 300% to the cost of the unit.
Says it all. The manufacturing cartels are laughing all the way to the bank.

 

[Corgigrouch]

Massive progress has been made but we are still a few years away from actually having Air source as our only heat source.... Correctly sized and applied airsource works well and will reduce heating costs

 

[Kev F]

4 bed detached, 1975. Cavity and roof insulated, heat pump is sole heating, legionella purge once a week, so far since turn on April 1st with snow on unit 3kwhrs, est cost £375. House runs radiator system no ufh
5am 21c
10am 20c
4pm 21c
1030pm 18c
Hot water 48c and legionella purge on a Tuesday sends it to 60c
Have a seperate meter put in that measures everything on heating and hot water ie ashp, all pumps, motorised valves, controls, switches and legionella purge.
Neighbours have filled twice since jan last year costing around £600, install grant of £1300, est yearly tarriff for 7 years at £650-700
Est install for mine would of been cost 16kw heat pump, 300l cylinder, controls, new consumer unit, new rads and valves 9-11k.
New oil boiler, cylinder, rads, oil tank 7- 8k plus 1k to fill tank.

I'm over the moon so far, I'll be saving at least 50% on neighbours old boiler and if I'd put new oil boiler I'd be saving 25-30% on oil cost.
Differance in install costs 2-3k, grant for ashp at 1.3k brings differance to 2k, saving on oil in first year if fitted new oil boiler £300-400
Differance now is nothing, bring in grant and I'm quids in.

 

[Kev F]

I'll add I've had over 2 units running on customers houses all similar to mine for over 2 years now and all are delighted, fitted 8 last year again all survived march/April where it was -4 for more than 6 hours which is very odd here, it really is down to the sizing and the situation, I've walked away from a few and said oil or nothing, one was 1400s conversion with 3 ft walls, listed with 3mm glass, I could of heated it but it would of had 3 units plus at around 20-30k install cost. He had oil in the end. You can get a 4bed detached at around 150m2 to get to around -10c if sized and run correctly, it's all about insulation, rad flow temps and location,me design to -3here but Scotland is -6c

 

[Norcon]

Hi All,

Just bought a house which has no central heating (brrr!) we're not on mains gas, so looking at oil boilers or air source heat pump as the two options.

We'll have underfloor or skirting radiators fitted throughout, which I believe should work well with air source heat pumps, but the technology is relatively new and I wondered if anyone had an experience?

Thanks

Your best option is a dual system with solid fuel imo.
Let a condensing oil boiler run the UFH and a back boilered multifuel stove run a few rads.
Simples.

 

[Corgigrouch]

Or the sane way would be to feed both heat sources into a thermal store and feed hot water, rads and underfloor from there....

 

[Kev F]

If you can get away with one heat pump I'd just run that, I've proved more than once its easy, either way I'd just use one heat source, it is far too costly combining.

 

[SuperMario80]

If you can get away with one heat pump I'd just run that, I've proved more than once its easy, either way I'd just use one heat source, it is far too costly combining.

Hi Kev,

My wife and I are doing a self build, we're planning on going for an ASHP to run underfloor on the first 2 floors, and a couple of large rads in the loft rooms. Unvented cylinder, also having a log burner, along with mechanical heat recovery and ventilation. Which heat pump would you recommend? The house is a 3 bed , with 2 extra loft rooms, 168sqm plus the loft space. 100mm cavity, 50mm celotex, 50mm air gap. We're also outing insulated plasterboard on the internal side of the external walls.

Cheers,

Dom

 

[roguetrader]

Technology is improving all the time, we put in several cheap Dimplex units last year and they are a vast improvement over the Nibe fighters we were putting in 4 or 5 years ago.
The biggest single factor in getting these machines working properly is the insulation you now see in new builds and refurbs.
Currently working on a new build 4 bed, 3 bath passive house with heat loss estimated at 3kw.
As Kev said, insulation and emitters sized for lower flow temps.
They do work in the right situation.