Air Source Heat Pump ASHP in a new build..
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I've been talking to a friend about them getting an ASHP... My initial reaction was don't do it, but are they now quite good?
It would be in a modest new build, 3 bedroom detached property. The area doesn't have mains gas, so is usually either LPG or Oil.
They are thinking of underfloor heating downstairs and then rads upstairs with an immersion for showers etc...
I just don't think they work well in the UK (South East England if that makes a difference).. although they seem almost determined and their plumber seems to reckon that they are the future..
Maybe an ASHP with PV or Solar thermal as well?
At the moment they are aiming to meet insulation requirements, but I guess that realistically they should be looking to exceed.
I suspect I'll have to leave them to their plumber... but as they're a friend I've tried to point out the issues as I understand them, but haven't got any experience. They seem fairly determined to go down the ASHP route.
Does anyone have any recent experience of fitting such heating in a new build of a similar size, what make + model did you go with? How big is the unit? The ones I've seen seem to suggest locating them 1 foot from the property and then they're about 1 foot in depth so about a 2 foot obstruction..
I've been talking to a friend about them getting an ASHP... My initial reaction was don't do it, but are they now quite good?
It would be in a modest new build, 3 bedroom detached property. The area doesn't have mains gas, so is usually either LPG or Oil.
They are thinking of underfloor heating downstairs and then rads upstairs with an immersion for showers etc...
I just don't think they work well in the UK (South East England if that makes a difference).. although they seem almost determined and their plumber seems to reckon that they are the future..
Maybe an ASHP with PV or Solar thermal as well?
At the moment they are aiming to meet insulation requirements, but I guess that realistically they should be looking to exceed.
I suspect I'll have to leave them to their plumber... but as they're a friend I've tried to point out the issues as I understand them, but haven't got any experience. They seem fairly determined to go down the ASHP route.
Does anyone have any recent experience of fitting such heating in a new build of a similar size, what make + model did you go with? How big is the unit? The ones I've seen seem to suggest locating them 1 foot from the property and then they're about 1 foot in depth so about a 2 foot obstruction..
As you say if they are going to consider using heat pumps then they need to plough as much as they can afford into getting the fabric efficiency as high as possible and air tight.
I have experience of an exhaust air heat recovery pump system and the actual running costs of the 2 bedroom homes came in at cicra £1400 per year; considerably more than the £500 quoted in the SAP's using the data provided by the system manufacturer.
I have no experience of this system but could be worth a look - http://www.thermaflowheating.co.uk/
I have experience of an exhaust air heat recovery pump system and the actual running costs of the 2 bedroom homes came in at cicra £1400 per year; considerably more than the £500 quoted in the SAP's using the data provided by the system manufacturer.
I have no experience of this system but could be worth a look - http://www.thermaflowheating.co.uk/
SE location might work well - unless you get very cold temperatures in winter, in which case it'll freeze up. I wouldn't be putting one up in Scotland.
Great for UFH, not so much for radiators. And you'll need an electric immersion heater to make sure your hot water gets hot enough to kill off legionella
Great for UFH, not so much for radiators. And you'll need an electric immersion heater to make sure your hot water gets hot enough to kill off legionella
I live in the SE and have a ASHP. Mine is under spec'd, 5Kw in a 100sq mt house. It powers all the rads and hot water, with no UFH. We pay £100/month for electric and the government pays me £100/quater for using renewable energy. The immersion comment is correct, the ASHP won't get much above 55, so you need something else to kill off bad stuff.
It's not been a problem apart from the really cold days, in which case the fire goes on. It's an old house, so lots of escapes for warm air/drafts!
Let me know any questions, I'll do my best to answer.
It's not been a problem apart from the really cold days, in which case the fire goes on. It's an old house, so lots of escapes for warm air/drafts!
Let me know any questions, I'll do my best to answer.
Aye, any rads will need to be larger than normal - standard flow/return temps with a boiler are 82 degrees flow, 71 degrees return - your ASHP will be more efficient (and less likely to freeze up when it gets cold) when it is run at as low a flow temperature as possible.
So BIG rads if the house isn't superbly insulated.
So BIG rads if the house isn't superbly insulated.
A friend of mine lives in Hobart area of Tasmania and has ASHP heating (reverse-cycle a/c). Because, in the England-like, Tasmanian climate the heat exchanger frosts up, they have to periodically heat the outdoor heat exchanger with a heating coil or it simply won't work. Seems like a nonsense to me especially as they have five acres of land under which they could have very easily buried a GSHP coil.
Our home is, this week, having ASHP installed.
As motco it is, apparently, A/C in reverse and the 'box' on the outside wall looks just like a A/C unit.
Our system will heat the water tank to "over 60 degrees once a week to kill bacteria"
If I remember I'll let you know how we get on but if I don't please email me!
As motco it is, apparently, A/C in reverse and the 'box' on the outside wall looks just like a A/C unit.
Our system will heat the water tank to "over 60 degrees once a week to kill bacteria"
If I remember I'll let you know how we get on but if I don't please email me!
skeggysteve said:
Our home is, this week, having ASHP installed.
As motco it is, apparently, A/C in reverse and the 'box' on the outside wall looks just like a A/C unit.
Our system will heat the water tank to "over 60 degrees once a week to kill bacteria"
Any heat pump can do heating or cooling - a few of the cheap ones made solely for UFH are heat only - but yep, the box outside is the same and can cool or heat. They are getting more popular now as gas-fired units for larger installations are very economic, typically around 4:1 kW put out/taken in. So 1kW of gas will produce 4kW of heat, or chilling.As motco it is, apparently, A/C in reverse and the 'box' on the outside wall looks just like a A/C unit.
Our system will heat the water tank to "over 60 degrees once a week to kill bacteria"
I've just had one installed on a big building over here - it serves the ventilation, which cools and heats the place.
The outside unit is about the size of two old phone boxes side by side, and uses a Nissan Micra engine apparently - but it is almost silent. Puts out around 32kW from what I remember.
Mitsubishi units are great, so are Panasonic - you can let them run in "dumb" mode, from a simple central heating controller, right up to altering the temp in every room in your house through a login address.
At the minute, from home, I can check and change the fresh air flow rate, temperature control, and humidity just by going to the login site and altering values. Or I can do it from my phone, which is handy when the client complains about it being too cold, and I can blip it up a few degrees. You feel it straight away, being a ducted air heat system.
Ours was finished (apart from snagging) on Friday last week.
I know it's not been that cold outside but I'm very impressed so far. The rads quickly get very hot and the hot water is very hot!
Ours is a Daikin system and the Daikin guy came today to fit a replacement valve, he was/is a refrigeration engineer and talking with him was interesting.
Neither of us could understand why it took so long for someone to come up with the reverse fridge idea - I walked passed the outside unit (the heat pump) last night when the heating was on and the cold air being blown out was very cold.
Which makes me wonder about the freeing problem, there is a lot of water in the drip tray coming off the heat pump, which obviously will freeze in minus temps, I'll try to get an answer when they come to do the snagging.
If anyone is thinking of having ASHP installed I can tell you who not to use in Yorkshire - no naming and shaming on here!
I know it's not been that cold outside but I'm very impressed so far. The rads quickly get very hot and the hot water is very hot!
Ours is a Daikin system and the Daikin guy came today to fit a replacement valve, he was/is a refrigeration engineer and talking with him was interesting.
Neither of us could understand why it took so long for someone to come up with the reverse fridge idea - I walked passed the outside unit (the heat pump) last night when the heating was on and the cold air being blown out was very cold.
Which makes me wonder about the freeing problem, there is a lot of water in the drip tray coming off the heat pump, which obviously will freeze in minus temps, I'll try to get an answer when they come to do the snagging.
If anyone is thinking of having ASHP installed I can tell you who not to use in Yorkshire - no naming and shaming on here!
My thread has arrived, must have missed it first time round.
I have about fifty underfloor heating jobs on the go at the moment - all with an air sourced hot water heat pump.(but it is New Zealand)
This unit from Wharf plumbing is much better value than any named brand:
http://www.wharfplumbing.co.uk/product/air-source-...
Try and have a 100mm concrete slab, then the heat pump can run in the day when temperatures are (relatively) higher and store the energy.
If you only have bedrooms upstairs, the temp up there will be a couple of degrees cooler than downstairs without any radiators at all.
The single biggest influence on running costs is have edge insulation for the slab.
All air sourced units freeze up below 7 degrees, they all reverse cycle to clear the frost about every half hour.
I have about fifty underfloor heating jobs on the go at the moment - all with an air sourced hot water heat pump.(but it is New Zealand)
This unit from Wharf plumbing is much better value than any named brand:
http://www.wharfplumbing.co.uk/product/air-source-...
Try and have a 100mm concrete slab, then the heat pump can run in the day when temperatures are (relatively) higher and store the energy.
If you only have bedrooms upstairs, the temp up there will be a couple of degrees cooler than downstairs without any radiators at all.
The single biggest influence on running costs is have edge insulation for the slab.
All air sourced units freeze up below 7 degrees, they all reverse cycle to clear the frost about every half hour.
caziques said:
My thread has arrived, must have missed it first time round.
All air sourced units freeze up below 7 degrees, they all reverse cycle to clear the frost about every half hour.
We looked at air source for about 18 months then decided as they would freeze up all the electric they use to reverse cycle defeats the object. 7 degrees in the UK is November to Feb at least so not much use as this is the time you need the unit to produce the heat. We went biomass in the end but ground source may be another option but its relatively disruptive to the ground.All air sourced units freeze up below 7 degrees, they all reverse cycle to clear the frost about every half hour.
The biomass has been great but we don't have a store so filling it with bags which is an ongoing exercise. The RHI payments will cover the install plus 10 years worth of fuel so not a bad investment but we do live in a 400 year old building with the worst EPC you could have.
FFG
Gas powered heat pumps (whether absorption or directly driven) don't freeze up, and cost about a quarter of a leccy powered one to run for a given output power - but they are a lot larger initial outlay.
Probably cheaper than biomass, mind, but still more expensive than you box standard "box with a fan" ASHP.
Probably cheaper than biomass, mind, but still more expensive than you box standard "box with a fan" ASHP.
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