Air-source heat pumps

[dave45]

My basement where my computers live is cold... even with a radiator it cools rapidly (it was 10.3 C this morning and I have been working from home all day). Otherwise the room is idle for long periods and an instant electric fan-heater is very handy to warm it up on demand. I have read in Mr Mackay's excellent e-book (http://www.withouthotair.com/) that a modern ASHP can be more efficient overall than any other form of heating.

But which model would approximate a 1-3kw fan heater and have the super COP figures? any experience out there? Can I fit one myself?

And what of cost? I'm guessing 20 quid for a nice fan-heater...

[mybarnconversion]

I'm not aware of any ASHP that costs less than several thousand pounds heat pumps are big fancy complex bits of equipment - take a look at that link for more info.

I've also had lots of tales of woe about heat pumps that have put me off ... so proceed with caution.

Are you sure your not mixing up ASHPs with something else?

If I were you I'd stick with a portable heater!

[snapdragon]

Isn't an air source heat pump just a backwards refrigerator?

[oldfella]

We bought a mobile air conditioner a few years back, and were surprised at the amount of heat coming from the outlet, however if we use the outlet as a form of heating in the spare room it just blows out cold air, so I suppose it just extracts the hot air from the room and just like a fridge leaves the cold air in the room.

[Millymollymandy]

We have paraffin/electric fan heaters which are brilliant and really warm and heat a very cold room quickly - they use paraffin for the heating which is dirt cheap and the electric is just to blow the fan/run the controls so they use very little electricity. One of our best buys!

[grahamhobbs]

Parrafin gives off lots of water when it burns, so be careful that you are not creating a condensation problem. You'll need plenty of ventilation.

[TheGoodEarth]

All the debate you need about ASHP can be found here.

http://www.greenbuildingforum.co.uk/for ... mit=Search

Have you thought about improving your insulation in the basement?

[Millymollymandy]

Parrafin gives off lots of water when it burns, so be careful that you are not creating a condensation problem. You'll need plenty of ventilation.

I know but as we mostly use these in our bathrooms they get all steamed up anyway and we have VMC in the house (that's French - Ventilation Mechanique Controlee ) so no probs there!

[dave45]

yes I have thought about insulation in the basement - when it was being made habitable I specified insulated plasterboard on all external walls, and I stuffed roof insulation behind the plasterboard on the internal walls. It just aint good enough. I need superinsulation... when will aerogel become available cheaply? It is nice and cool in summer though :-)

I have yet to see a graph of an ASHP's COP against source temperature, which lead me to believe there is something to hide.

I too thought they were stupidly expensive until I saw some on ebay a few months ago for a few hundred quid, with allegedly easy DIY installation.... none there now.

This is the relevant bit of Mackay's book http://www.inference.phy.cam.ac.uk/with ... _150.shtml

I think fan heaters are great... local shop has a choice of just one. its a tenner.

[Green Aura]

You mentioned the walls Dave. Have you insulated the floor?

We live a concrete barracks building with solid concrete floors. In the shop area the floor is bare and there is a huge drop in temperature between the house and the shop. It seems to work like a huge heat sink, but then doesn't seem to give any heat back out

In the house it's insulated with polystyrene (not our choice), chipboard flooring and we've gone over that throughout with cork tiles. Much warmer.

[dave45]

The basement is of limited height unfortunately. There is a new concrete base, a rigid plastic membrane, then approx 1cm of special levelling wooden boarding then underlay and carpet. There is also an underground dbl-glazed window and I have covered it with scrap polystyrene foam. It just isn't enough. I'm running out od ideas. I guess it just aint possible to retrofit decent insulation to old houses.

Despite being mainly underground it DOES seem to be linked to outside *air* temperature - a few degrees warmer these past few days.

meanwhile, out in the garden the soil is workable at the surface but still frozen 4-6 inches down.

[merv]

Coming a bit late to this post. Sorry.

We have two ASHDs, both installed about five years ago. The first, for the living room, was self installed - main unit on the outside wall, insulated pipes leading up, through the wall and venting inside at ceiling height. consumes about 1kw when actively heating/cooling, with a COP of 2.5 ie 2 to 3 kw of effective heating/cooling.

Cost was about 200 pounds. Maker is DeLonghi. Check their web site. As our living room is quite large 50sq m it is slow to heat up so we only use the ASHD on those days/mornings when it isn't worth lighting the fire.

Other unit is for the bedroom but had to be installed for us as the pipes needed lengthening. On a timer it just heats the bedroom from 10pm till beddy-byes.

I swear by them nowadays, small, discreet, cheap and (for the units we got) easy to install.

I don't have a witty sign-off but having just completed 50sq m of parquet, and if I may borrow someone else's, I feel like the lampost.

Merv

[dave45]

Thanks for that Merv...

by the by - we went round CAT (Machynlleth) on the weekend.. I was wondering whether their exhibits would mention ASHPs or Aerogel superinsulators.

Zip. zilch. nada. nishto. nothing at all.