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Rosy
08-12-2006, 09:52 PM
Hi Everyone from a newbie :)

I am interested in the commercial viability of heat pump installations in normal family homes (3 bedroom, postage stamp garden). Probably air sourced?

What are experiences from countries outside UK - are we missing out?

Are radiators the low cost answer or maybe a blow air system - underfloor is an expensive solution?

I am interested in any opinions!

Thanks :) :) :)

Pooh
08-12-2006, 10:34 PM
Rosy
is it a new build or an existing house?, for a new build underfloor with a heat pump is best as you do not need such high temperatures from the pump. The size of the garden does not mean you have to rule out ground source as bore holes are an alternative. More info will give me a better idea of what to suggest and I may be able to put you in contact with somebody in your area who may be able to give you a little help.

Ian

Peter_1
09-12-2006, 09:21 AM
See you're living in Scotland, so cold winter conditions.

But, also conditions where an airsource heatpump will perform not that well, whatever commercial brochures will tell you.
And when is a airsource HP performing the worst? Right,..the moment you need it the most.

So, I should go for a ground source and if I may give my opinion, choose for a DX one, performs much better.
No pumps, not to worry that the refrigerant will freeze, no need of antifreeze, cheaper machine, cheaper installation and most important: a much better COP.

If you want to do it horizontally, then you need +/-2.5 to 3 times the house surface in your garden.

My advise should be; install a vertical DX ground source HP.

With the rising fuel and gass prices, a GSHP is the way to go but...connected to a low temperature water system in the house, radiant heating as a first choice or radiators selected (big ones) for a low water regime or fan coils.

Pooh
09-12-2006, 01:40 PM
Peter
there is a issue with DX in the UK and Europe are also encouraging people not to instal them, I have just got a Dimplex air source machine to play with and we are getting really good results with air on temps to the evaporator of Zero Centigrade which taking the number of days the air temp is that cold it is looking good. I am hoping to get a Veissmann machine to play with as well soon hopefully a couple of groun source machines also.

Ian

davej
09-12-2006, 07:41 PM
Hi pooh, could you enlighten me as to the Issues with the dx system please.
it seems to me that the gshp association is in the main operated by the companies that only supply glycol systems but they do not achieve temperatures that the dx can.

Peter_1
09-12-2006, 08:05 PM
Peter
there is a issue with DX in the UK and Europe are also encouraging people not to instal them, I have just got a Dimplex air source machine to play with and we are getting really good results with air on temps to the evaporator of Zero Centigrade which taking the number of days the air temp is that cold it is looking good. I am hoping to get a Veissmann machine to play with as well soon hopefully a couple of groun source machines also.

Ian
1. Why they dis-encouraging installling DX HP's? I think I know but I want to know their reasons.
2. How is encouaging this , you say Europe..:confused:
3. What are good results? What COP's do you get and especially - I call it so - the 'overall COP' (pumps included) because this is for me the only valid parameter to compare HP's?
I personally never saw a HP on a glycol base and certainly not an airsource one achieving a COP of more then 4 when it's outside 0C.
I have in front of me the real figures (datasheet) of an R410a VRV machine and the machine gives a COP of 3.7 (which isn't that bad of course)
But, a DX can perform at 5 and even more. Calculated over the years....!!

You have a point that it rarely becomes colder then 0C but even then. On teh other hand, the ground never becomes colder then 0C, even 10 C when proper designed.
What about the price of a DX compared to a glycol based system? The work to install the heatsource in general is +/- the same for both systems.

For the rest, you need a compressor, an enclosure, a switch-cupboard, a TEV or EEV, a receiver.
But only 1 heat exchanger(!), no pumps, no glycol, no purging system,

I'm interested in the results you can provide us.

davej
10-12-2006, 02:37 PM
im with you on that peter, average ground temp ere around 1 deg c ,we are at present evaluating dx gshp's but they seem to be doing quite well. we have some running hot water up to 50 deg c and also doing a hot air and air con system (unico)
working fine. so far so good

Pooh
10-12-2006, 03:17 PM
The issue of running the extra pump does not really effect the overall COP as the pump is only very small. The main issue with DX ground source is the large quantities of refrigerant required, all the governing bodies are pushing towards reducing the amount of refrigerant we use. The other point is the cost of tubing for DX systems which as we know is increasing in cost daily. The third issue is the fact that most heat pumps are being installed by plumbers who have not got a clue on the requiremnts of a refrigeration system, during a recent course I was told of a DX ground loop that had been pressure tested using water by the installing plumber, his comment was I did not know that would cause a problem. As with everything new to this country we need to talk to the people who developed the technology over the last couple of decades, The Germans and others are using mainly secondary systems as they have encountered the problems with DX.

Ian

Andy
10-12-2006, 06:24 PM
im with you on that peter, average ground temp ere around 1 deg c ,we are at present evaluating dx gshp's but they seem to be doing quite well. we have some running hot water up to 50 deg c and also doing a hot air and air con system (unico)
working fine. so far so good


Ground temperature would be around 10 deg c, that would be the real reason for using GSHP:)

air temperature average in the winter would be 4 deg c:) the problem is when the -3 deg c day comes you may loose your heat the very day you need it most:eek:

I hear a lot of good reports on DX heat pumps, but I would have serious reservations on using them:confused: just too much hassle for the average domestic installation I fear:)

Kind Regards Andy:)

davej
11-12-2006, 09:59 PM
your right andy i miss typed the temp as 1 and it should read 12 which is what we use as the earth temp.

taz24
12-12-2006, 03:33 PM
when dealing with secondary cooling and heating systems if you place the pump in the feed pipe then most of the energy used will be transfered to the water as heat.

taz.

taz24
12-12-2006, 03:35 PM
I know of a closed system with no other souce of heat that with just the pump running added 30k of heat to the water temp.

taz.

Chris Burton
02-01-2007, 09:09 PM
Daikin are doing altherma a split air source heat pump systemwith DHW tank for for about 2.6 k with discounts. I'm buying a 1930 detached 3 bed with no central heating. i'm going to fit underfloor heating as if the operating temp goes over 40 c the COP drops. Can anybody recommend any alternative system manufacturers as when you mention the word GREEN companys slap on a hefty price:confused:

The MG Pony
19-04-2007, 07:42 PM
Starting to smell like advertising there Bitwobbly, once I can see twice it starts to smell ;)