Ground Source Heat Pumps

[C-NUMB]

Originally Posted by Polwart

How much access do you have to pelletted wood? it strikes me that almost everyone I speak to is looking at woodburners and pellet fired boilers (either as "eco bling", lower cost, or whatever). If this is someone's main source if heating it will need a lot of wood - which if everyone goes over to that route the "wood pellet people" will respond to market forces and hold you to ransom instead (unless you have your own wood and the time and inclination to harvest, dry, pellet etc yourself). I wouldn't be surprised to see the local kerosene suppliers becoming the dominant supplier in wood either!

This is a very good point. Market works, sooner or later, always. The availability of wood
bricket's, pellets or chips might be a interesting issue in a soon future. Many of traditional coal/ fossil fuel power plants have plans to significantly increase(or to start) use wood based energy. This also in areas without much own domestic supply. It seams that demands will exceed supply easily. How much this will impact on price on pellets for household burners is hard to tell, but raw material is anyway the same.

In the long run a multifuel option might be a cleaver solution, and would not exclude electricity, as i am not at all sure that this biofuel thing will last very long. Considering the transportation/ production "footprint" biofuels are maybe not so green after all.

[Nos4r2]

Originally Posted by spartacus

I hate being held to ransom by the oil companies, as the price of kerosene goes up continually.

It should come down soon-it's already dropped from the massive peak before Christmas.

Incidentally,heating kerosene is duty free and at a rebated VAT rate so the government has very little to do with the price.

[chewy]

Originally Posted by Nos4r2

It should come down soon-it's already dropped from the massive peak before Christmas.

Incidentally,heating kerosene is duty free and at a rebated VAT rate so the government has very little to do with the price.

It similar to diesel too......

[Nos4r2]

Originally Posted by chewy

It similar to diesel too......

Not really-it's not 'oily',so won't lubricate your fuel pump.

A diesel will run on it, but it'll bugger it up.

[BumbleAbout]

From memory when I investigated heat pumps a few years ago, there were very different efficiencies available (listed in order of increasing installation cost):
Air source about 2.5 : 1
Ground source (pipes buried under grass) about 3.5-5:1
Water source (borehole or running stream/ river) up to 8.5:1

So for every 1kw of power to keep the compressor going you would get about 2.5kw of heat out (for an air source system).

You can design the system for the very coldest days of the winter (relatively few in the UK), but it is much cheaper to have a system designed to cope with average winter temperatures and then top up on the coldest days with an alternative heat source (we have drastically reduced our oil consumption using a woodburner for instance, so it's not a problem to continue with this).

If it is designed in from the start (i.e. with underfloor heating pipes in every room) then it works with a constant low heat running 24x7 - very differently to our standard couple of hours in the morning and again in the evening. This also requires some good insulation to be efficient !

When our oil boiler dies, we will replace it with a water source heatpump - but the break even time obviously depends upon your current fuel useage (we have an old house and use lots of expensive oil)!

I haven't found any installers who have experience of air + ground + water based systems who are able to give good comparisons however, so lots of myths still circulate ...

[Chris]

Just a Postscript to this thread.

I have had one of the Mitsubishi Zubadan (ecodan) air source heat pumps fitted. So far so good with upto 60 degrees of hot water and heating available at a much improved cost from the old Calor Gas combi.

The Mitsubishi is supposed to work down to -25 and is fully functional for upto 60 degrees of hot water / heating even at -15 degree outside temps. Time will tell and worst case is we have the log burners going more during the really cold periods (assuming we have a winter like we did last year)

At a later date I may put in some solar which will effectively mean the Heat pump is hardly running at all during the summer and hot water will be supplied primarily by the solar panel.