Poly tunnel heating system
 

This is stage 1 of my new improved 2009 heating system. (see pics in my gallery)

Having cost me a fortune to run last year (and not working that great) the 2.5kW electric blow heater has gone to Devon via ebay.

Now for 2009 we have stage 1 which is a 3.9kW air to air heat pump.

output is 3.9kW but input is only 1.25kW. For those not familiar with heat pumps it's basically an air con spilt unit, but applied to heating. Control is via
a standard heating controller, temperature is set to 9 degrees C.

The controller has 2 channels which means the same controller will be also be albe to control...Stage 2 - under construction will be an air to water system feeding a 100M subsoil hose coil, will post photos when it's done.

Anyone need more details just let me know.

Re: Poly tunnel heating system
 

That is good but also expencive system. I heat my home thatway with 3.6Kw pump and its good if temp. doesnt drop below 5C than we have problems with compresor freezing and simmilar. Good luck is that it happends rare, once or twice a year at most. Also good thing is that U can control humidity with this sys.
Good luck
:woohoonaner:

Re: Poly tunnel heating system
 

The outdoor unit has an 'auto de-frost' function so the unit will work down to -15C. It's the cheapest way to do it without using solar thermal stores etc.

Re: Poly tunnel heating system
 

Agree. Problems start in case if U turn it off while "auto de-frost" is turned on wich man cannot know whan is it becouse there is not indication for that program (in my case). Whan U try to start it again "auto de-frost" stays in unit memory and it cannot start compresor on any programs again. Than U have to manualy de-frost it, swich power suply of completly so it can start normaly again. Hope that Im only one with this problem hahaha
:woohoonaner:

Re: Poly tunnel heating system
 

Very interesting Kev i shall be watching this thread with a great deal of interest, looking at the concept here;

Air source heat pumps - Generate your own energy - Energy Savint Trust

the potential savings are significant.

Re: Poly tunnel heating system
 

I use a Air to Air heat pump to heat and cool my house its pretty good on the heat part but the cooling is expensive how ever we do not have that harsh a climat it only gose below freezing a hand full of times a year we did have a year when it whent in to the teens that would be mabe -20c for you all it handaled it fine but i know the flum heaters were active alot of the time as it has an indacater light the tells when its on i mise the good old Natural gas heaters we ues in the mid west US they are much easer to fix

dont you have acsses to natural gass at your home would be a heck of a lot cheeper to buy ?

Re: Poly tunnel heating system
 

Right now I'm using a 1.5kw fan heater in my greenhouse which is set at 15c,to maintain the greenhouse at 10c in the winter months,just to keep all my nanas alive.I work at a plumbers merchant and I'm thinking of going for ground source heat to keep my house warm in the winter months,hopefully i could keep my greenhouse warm at the same time.I have talked about it with a few people and they think there is no reason why it wouldnt work.

Re: Poly tunnel heating system
 

There is no reason at all why it wouldn't work.

BUT

If you have nat. gas available then you're wasting your money on a GSHP unit for at home. you're looking at an install cost of £12k and unless you have underfloor heating or oversized radiators the COP will not be what you want.

Re: Poly tunnel heating system
 

Hi Alan

I'll update this when I get the air-to water unit working. and give me a shout before you buy anything.

regards
Kev

Re: Poly tunnel heating system
 

Yes I do have nat. gas but it wouldn't be cheaper. not sure about the US but here in the UK electric is about 3 x the price of nat. gas per kW.
If a gas heater was 100% efficient (which it isn't) then I would input 4kW of gas to get 4kW of heat. to get 4kW of heat from my heat pump I input 1.25kW of electric. an efficiency (well COP actually) of 320%, therefore electric is cheaper.

Re: Poly tunnel heating system
 

Hi Kev

just rang around few reps while i was at work today who i know, they recon they can get me the GSHP system for 7k and that's including putting under floor heating in.

Re: Poly tunnel heating system
 

what output heat pump? ground loops or borehole? with buffer vessel? litreage?

Re: Poly tunnel heating system
 

Natural gas is cheaper here in the US then Electric guess it depends on were you live North America is a vary big content here in Las Vegas the ground is so hard below 5 to 10 ft the you have to blast it with explosives or use a jack hammer this layer is called Caleacha its a prehistoric layer of clay and volcanic rock that has solidified so digging trenches or wells to place ground sours heat pump would cost 30k or 40K the system would ware out before it ever payed for its self its to bad to as Nevada has ample Geothermal heat there are hot springs all around the city is an ancient site of a large Volcano and we are only 90mils from death Vally the largest abduction falt in North America not to stray from the topic but the Geology here is complexes and highly fascinating if i had a hot spring id tap in to it for heat but the number of heating days here are of course vary low in comparison to the number of cooling day in a perfect world id use Magnetic cooling heheh wouldn't that blow every ones mind

Re: Poly tunnel heating system
 

Another 10-15 years if some new technology doesn't come out we probably will all have magnetic refrigeration!

Re: Poly tunnel heating system
 

Hi Kev

The output of the heat pump was 25kw,and the borehole would have to be 20mt,for my house.

Re: Poly tunnel heating system
 

a 25kW heat pump will need 3phase (400V) electric supply. also a borehole in average ground conditions produces (in the UK) about 1kW per 15M bore, drillers don't like going much beyond 100M, so for 25kW your looking at possibly 4-5 boreholes. minimum separation of 6M.

Re: Poly tunnel heating system
 

Hi Kev

Just doubled checked today,and 20m boreholes would not be enough,for the pump size that i would need,to get this information i had to ring the technical department of these company's.

Thanks

Mushtaq