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

I know how to use to nibe more that the installer infact but it eats electricity and is noisy as the compressor is indoors,

harryhound wrote: »

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.

andrewjwaters wrote: »

I dont know wether I have the right place for this question, but here goes.
I am building a Sussex barn conversion, it is approx 240sq m. I have fitted 150mm celotex in the walls & warm roof construction, 50mm in the floor under the underfloor wet heating system.
I have fitted a multifuel Rayborne [Wood/coal] with a gravity hot water system feeding a 300 litre heat store. Ditto with a wood/coal stove in the lounge, I have fitted solar panels to assist water heating in the summer.
I was going to fit a ground source heat pump but have read some real horror stories so I was looking for some inspiration as to the suitability of an indoor Air source heat pump?
Thanks
Andrew

As you are going (correctly) for underfloor 35 degree heat pump technology, with wood/coal as a back-up for cold external temperatures; putting down a floor and then digging it up again is presumably not an option.

The ground source option is theoretically twice the price mainly because of the ground works. Presumably you are going for a network of pipes a meter or more below the garden?

This won't turn into into an ice making machine, requiring the massive ordinary immersion heater a back up so often.

"Build tight ventilate right" is the mantra after putting in maximum insulation.

Have you paid someone to do a detailed assessment of your building or have you only spoken with a cross between a second hand car salesman and a life insurance salesman paid on commission?

Is the assessment capable of measuring the thermal mass of your building and its thermal gain through its (treble?) glazed coated windows.

In my mind's eye I can see you living in a structure like a church made of wood and clap board; is it anything like that?

I would be a bit worried about the heat building up at roof level.

I have some misgivings about your ability to prevent condensation getting past the "Celotex" (other brands are available) and building up against the relatively cold timber structure or are you doing one of those building within a building tricks? Never never use a condensing clothes drier!

Is there a listed building aspect to what you are doing?

Having said all that there are some happy stories on here, especially for expensive new builds.

Let us know how you get on.

Harry

PS I have no formal qualifications in any of this - nor very often do some of the cowboys selling the technology.

At what temps should defrost cycles be kicking in? When we had some frosty weather the other week i noticed the defrost cycle kicking in quite often during the evening (I live in central Scotland). It kicked in last night once (that i noticed) and i expect it to kick in tonight as it seems nippy outside.

Is this normal at these temps?