NEEPS

jaydee67 · Posted: Thu Oct 22, 2009 12:25 pm Post subject: air source heat pump

We are looking at installing a wet heating system powered by an air source heat pump to replace our storage heaters. Anyone got any experience of these/ things to look out for/ etc?
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lachlanandmarcus · Posted: Thu Oct 22, 2009 2:42 pm Post subject:

I heard they arent quite as good as ground source, but of course they dont need the earthworks either!

There is a competition in this months Homebuilding and Renovation mag to win one of two air source heat pumps (one 12kw worth £3150, one 3kw worth £1150) so you might want to see that (Nov issue, you can enter online too at homebuilding.co.uk/competitions apparently)
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Martin · Neepster Joined: 16 Sep 2007 Posts: 663

In this area they are GROSSLY oversold - the salesmen are very good at muttering about the "free" energy, and conveniently overlook telling you to do your sums VERY carefully (if you have mains gas, they really aren't worth it) - the sums go thusly - for 4 units of gas - 12p, for heat pump, 4 units of heat, 1 unit of electricity in at 12-15p............plus the 3 "free" units -4 units in total, costing more.........
Other downsides of air-source is that they are bally noisy, and are fine down to around 45 degrees fahrenheit - below that. efficiency is severely impaired, and they often ice-up (meaning you'll probably need to have another heat source when it gets cold.........).
The ONLY way I've ever made the sums make sense for heat pumps is for a new build where they are generating their own electricity. where it is possible to put in underfloor heating (not an easy "retro fit"), and they can afford, and don't object to the upheaval of ground-source..... - the heat output is "low grade" - at too low a temperature for proper existing radiators - only really works well with underfloor..........
You may guess, I'm NOT a fan.............

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jaydee67 · Posted: Thu Oct 22, 2009 2:52 pm Post subject:

Thank you, competition now entered!

They are less efficient than ground source, but that's not an option here.
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Julia

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Martin · Neepster Joined: 16 Sep 2007 Posts: 663

I hope you win - in all seriousness, don't rip your old night storage heaters out before you've had at least one winter using the heat pump - you may be very relieved to return to your "old fashioned" night storage jobbies - on the right tariff, they still make a lot of sense, and are usually a lot more effective than trying to shovel the output from a heat pump through "conventional" radiators........

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jaydee67 · Posted: Thu Oct 22, 2009 4:27 pm Post subject:

It's the lack of controllability with the storage heaters that drives me nuts! We have booked a energy assessment home visit so we will see what he comes up with.
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Julia

New blog: http://jaydee67.blogspot.com/

Martin · Neepster Joined: 16 Sep 2007 Posts: 663

ps, I always tend to wonder if I've "overstated the case" sometimes, not least, this thread - as you may or may not know, I moderate on a renewables forum - having made my the above post I returned to that forum, and read the newest few posts, and one hit me in the eye (from a leading member, someone "in the business", who really knows plumbing and renewables), which I append below..........

"The scenarios I have already come across are ASHP fitted to radiators systems that just DONT WORK (fitted by professional companies!)"

-be VERY careful! - it's not just me!
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Martin · Neepster Joined: 16 Sep 2007 Posts: 663

I think the problem comes from the fact that most companies are flogging one or two technologies, so the temptation is for them to flog you "what's on the shelf", whether or not it's the best thing for you, and to be bluntly honest, many so-called "energy experts" haven't the first bally clue (and are often in the sway of the snake-oil salesmen)

I'd suggest the following - firstly, look carefully at precisely how much your night storage heaters are actually costing you (and very particularly the cost of waterheating, if that's done by an immersion heater) - sometimes fortunes can be saved by putting the immersion on a time-clock to only come on during the "off-peak" times -
THEN check your insulation - insulate till it's coming out of your ears - often there are good grants available, you'd be daft not to take them up, THEN look at all the alternatives that are available/suitable for you in your situation, and preferably try to talk to someone who's already "gone that route" - a recommendation from a neighbour who's lived with a technology for a year or two, and is happy to show off their tiny fuel bills is the best advert.
If you'd like any help on making the right choice for you, I'd be very happy to try to help on the forum, so it may be of use to others........
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JamesB · Posted: Thu Oct 22, 2009 8:15 pm Post subject:

yep, agree with everything that has been said. they are hard to justify except for new builds off the mains gas.

just curious, you said ground source not an option. just wondering why? they need little space outside if drilled vertically. yes I know more expensive but worth looking into. we had one years ago, retrofitted to a stone cottage, small system (4kw out) and with radiators but worked out well but only worth doing if everything else has been done ie insulation and draughtproofing.

James
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Mintlaw area