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

TiredGeek · 4 September 2011 at 10:03PM

albyota wrote: »

TiredGeek, did the systems come direct from Mitsubishi, I suspect not....your installer probably had no idea what tanks to get. Call Mitsubishi, get them replaced, if you need some contacts let me know.

As you suspected, they came from the ASHP installer along with the Mitsi units.
They do need replacing, at the moment I'm persuing full refund for the system and then we'll get in a company who knows exactly what they're doing

I'm sure it's going to get nasty before it gets better, but I have plenty of evidence of poor service from the installer so if REAL don't do anything then Trading Standards are keen to get involved

albyota · 4 September 2011 at 10:26PM

TiredGeek, I wish you luck in getting it sorted, I'm sure you will, in the meantime, check the flow rate it should be about 40 Litres/minute for the 14kW units, I remember you stating that it had been set to around 25L/m.

TiredGeek · 5 September 2011 at 3:38PM

According to Mitsibushi Technical flow rate should exceed 18L/min but be lower than 40L/min.
No matter what we do we cannot get the flow rate above 25L/min with the 15/60 pumps that were specified in the instalation manual. As they are £115 each and we have 6 of them I don't particularly want to replace them with something bigger. Even when they draw from a low loss header the flow rate remains the same, I'm either at the limit of the pumps (though Grundfos say I'm not) or the Mitsi unit is so restrictive internally that 25L is all I'll ever achieve.....

Storm20 · 5 September 2011 at 8:36PM

I have been reading for days now about ashps and I think I know enough now to ask a question.

I have put an offer on a small townhouse, which has been accepted.

It is two storey, downstairs is 21 sqm living/kitchen. Upstairs is 21 sqm divided into 2 similar size bedrooms and a shower/toilet.

The heating system is "Electroheat" which as far as I can see is water heated by an electric element and pumped around radiators.

It has been empty for some time, the radiators are shot and there has been a burst somewhere in the Boiler/hot tank area. I am valueing the heating at less than £0.

Gas is not an option, nor is oil since there is no place to put a tank. I don't suppose one would get away with bolting an oil tank to the wall.

So I am thinking this might be an ideal set up for a ashp.

Since it is so small an air duct system might work ? I could use electric for hot water and cooking.

s

albyota · 5 September 2011 at 9:45PM

Storm20 wrote: »

I have been reading for days now about ashps and I think I know enough now to ask a question.

I have put an offer on a small townhouse, which has been accepted.

It is two storey, downstairs is 21 sqm living/kitchen. Upstairs is 21 sqm divided into 2 similar size bedrooms and a shower/toilet.

The heating system is "Electroheat" which as far as I can see is water heated by an electric element and pumped around radiators.

It has been empty for some time, the radiators are shot and there has been a burst somewhere in the Boiler/hot tank area. I am valueing the heating at less than £0.

Gas is not an option, nor is oil since there is no place to put a tank. I don't suppose one would get away with bolting an oil tank to the wall.

So I am thinking this might be an ideal set up for a ashp.

Since it is so small an air duct system might work ? I could use electric for hot water and cooking.

s

Either Air to water heat pump(Ecodan/Panasonic/Daikin/Sanyo/LG) or Air to Air (Mitsubishi/Fujitsu/Panasonic) (3 or 4 or 5 way split) individual wall mounted units are often percieved as an ugly box on the wall, although LG have their 'Mirror' or 'Artcool' can be quite pleasing to the eye, if re-furbishing, built-in ducted systems can work, however they are both going to be a similar capital cost to install, circa £5K - £6K, heating water can be done with the A2W efficiently, but with A2A your hot water would need be heated with direct electric, so running costs would be higher. As you need to replace the radiators, it might be the better option as the pipe work is already there, and as long as you replace with correctly sized rads, the A2W system would have lower running costs. If you go down the A2W route with rads, get 3 or 4 quotes from MCS AEI installers that carry out all the work. Alternatively replace with an electric element boiler (cheap to install....expensive to run).

Things to consider:

Is the house very well insulated i.e.cavity wall / roof / double glazed / ground floor solid or wooden? insulated?
are you likely to get planning permission for a heat pump (either type)?
is there space for the outdoor unit/s?

As much as I hate them....are night storage heaters an option?........ actually.....forget I mentioned them......:eek:

Storm20 · 5 September 2011 at 11:13PM

Thanks, I will digest that for a couple of days.

I read about the guy who put the pump in his roof space and it didn't work so well.

If there was plenty of fresh air getting in and the cold air and condensation was ducted out could it work.

s

richardc1983 · 5 September 2011 at 11:25PM

Storm20 wrote: »

Thanks, I will digest that for a couple of days.

I read about the guy who put the pump in his roof space and it didn't work so well.

If there was plenty of fresh air getting in and the cold air and condensation was ducted out could it work.

s

You might as well just mount the unit outside,the extra expense and risks you are taking mounting a unit designed to go outside are not worth it.

You can buy self contained uints that have intake and extract ducting on them if space is limited but these cost a lot more money.

harryhound · 4 October 2011 at 9:48AM

jeepjunkie wrote: »

Still can't believe how brilliant the ASHP is... Last year as the nights drew in this old place cooled down and felt cold. Now its warm and cosy and still £20pm. Pah to the naysayers!

Cheers

The first heat pump installation in the UK was in 1949 (unless you know better;)). Similar autumnal remarks were made then.

Please give us some real figures during a sub zero fortnight in January; including those for the back up source you will be using.

Good luck,

Harry.

jeepjunkie wrote: »

Despite our EcoDan being cheap to run the wife is keen on being self sufficient energy wise either by solar pv or from our river.

I know of a small community of 3 households built into what was an old water mill complex.

The stream comes out of a chalk spring and so. like a water cress bed, tends to have the same volume (and temperature) year round.
So far they have had some sort of feasibility study done - the old listed stone structures are not really suitable for heat pump technology but the "modest" volume and fall of water is supposedly worth an output of 13 kW.

*Make a note to diary* If I'm in the area call in and see how they have progressed.

harryhound · 6 October 2011 at 12:18PM

You do find horror stories like this one on here from time to time:
http://forums.moneysavingexpert.com/showthread.php?t=2959648

It appears to be mainly bad design coupled with users who have had no expert instruction in how to use the new heat pump technology.

I'm not a complete idiot, but how you can suck warm moist air out of the home and pump the heat back in, when the outside temperature is sub zero escapes me.

The system must be sucking the inlet air of the heat pump (at zero degrees) through the house and then when and if it has been warmed up getting the heat out again.

Might have some function as a dehumidifier/ice maker, but I cannot see how it will ever heat the homes.

richardc1983 · 6 October 2011 at 5:34PM

I echo the last comment above they are different from the NIBE in the link you mentioned. Proper air source heat pumps need access to the outside air. The nibe recovers heat from inside the house which is fine in summer when you want ventilation but in winter they ddint think that you would be dragging freezing cold air into the house to replace the warm air it sucking out. Its ok to recover heat from inside if u was venting it outside anyway eg bathroom or ventilation but to rely on that aatue heat source is crazy as u can't create something from nothing!

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

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