[Closed] Air Source heat pumps (boilers)

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I think they were a bit iffy to begin with. The problem was low grade heat (55degC I think which was dodgy for radiators) but now the mitsubishi ecodan comes with a cascade refrigeration system allowing higher temps. Very efficient, and the tech is proven but electrical energy will be more expensive than natural gas. I have a mate who works for mitsubishi if you want a contact for info.
My advice is make sure that the output matches your requirements during the coldest winter months. eg, if you know you need 25Kw of heat; make sure the system can deliver it at -5degC, and is [b]NOT[/b] 25KW nominal duty.

Thanks for that. We've found the low grade heat ones are the only ones which you can get grant aid for. Apparently a lot of them start to struggle at -3degC, which is a bit concerning, but the immersion covers those times - plus we have a wood burner. I'm willing to pay a little extra to get rid of the bulky oil tank - we're nowhere near mains gas. I'd like to hear 'normal' folk having been impressed with them ("so why post here?" I hear you say). We don't have any land, so ground source is a non starter and moving the oil tank to make room for a small extension is going to cost £700 - add to that the age of the boiler, and costs become more reasonable long term.

The mitsi kit can also come with a tank complete with top up heater and has the advantage of being controlled via a common electronic unit.
Take a look at this;
http://www.mitsubishi-heating.com/ms_homeowner.asp
I can recommend mitsi kit having used it in a professional capacity many times, and you know that you're buying refrigeration equipment (because that's what it is) from the experts. Says that you can get grants on that page. Daikin also do the altherma range.
What's your load (in KW?)?

boxelder,
Like you, we don't have gas and have to use expensive oil, plus space in a small garden for a tank. We looked at air sourced heat pumps last year and it seems like a no brainer. No oil, just a bit more electricity. We were quoted about £6000 but since our existing boiler is about 20 years old and will fall apart soon the pay back isn't too bad. The only reason we didn't go with it is that we were about to fit a log burner so we wanted to see how that changed the oil useage over the winter. If and when out boiler dies I'm sure we'll look at air sourced pumps again.
PS Just check how much noise they make.

Boxelder, where are you based? I have contacts in ASHPs and solar thermal, etc.

It's not as straightforward as replacing a boiler - you need to consider what you're heating, e.g. normal rads/low temp rads, underfloor heating, hot water, etc, because you can have a nice piece of kit installed perfectly, but if it's working way too hard to create the desired temperature, then your return is going to go right down.

SM

Thanks all. Based N.Lakes. We've had a couple of firms look into it for us. One is looking at KW needs etc and getting back to us. I just wondered if anyone here had gone down that route and what was to look out for. The Mitsubishi site looks interesting, thanks. Noise? - from 'exchange unit' or boiler?

Unfortunately I don't know anyone in your part of the woods, although I'll see if I've still got the number for the SD at HeatKing. Based up north IIR and bound to have an installer who can at least speak to you over the phone or pop round. Email me your details if you're interested.

Whatever you do, deal as much as you can with installers/engineers as opposed to sales people. The former are more likely to live in the real world in terms of returns.

SM

Well good luck with whatever you choose. If you need any impartial advice; I'm happy to help. ndobbsieATmsnDOTcom.

Not sure about it as a boiler but we have 2 AS heat pumps - Daikin ones.
Watch our for low temperature performace as said before. we are ok as it rarely gets below 0 degrees but even at that temp its nowhere near as effective as it should be. Have friends who have had major problems at -5 further south - just doesn't heat any more. Our inverters are almost silent.

Thanks chaps.
Awaiting a few possible specs from local firms and will be in touch (as offered) if things don't seem right. Mitsubishi have a fairly local installer, so will look them up. Glad to hear the noise isn't necessarily too bad.