Re: Turn your home into a mini power station...

[W T Taylor <bill-taylor@xxxxxxx>]

BP> Yes. I've got one in my barn conversion. Got a few teething troubles
BP> with the controls to sort out (mainly to do with how it combines
with
BP> the LPG boiler), but basically it works fine. Just a question of
getting
BP> the right bit of kit having priority at the right time (it's quite a
BP> complicated system).

BP> For a UK manufacturer, have a look at Kensa Engineering's website -
BP> http://www.kensaengineering.com.

BP> The statement in another message that the payback on all these
BP> technologies is too long is probably wrong for heatpumps now. You
can
BP> get £1200 grant from the government towards the cost. Take that off
the
BP> typical £3000 - £4000 for buying and installing an average-sized
BP> domestic heatpump and ground loops, and it's not much more expensive
BP> than buying a normal boiler. In theory, it shouldn't take long to
make
BP> back the money from the energy savings. At least, that's what
Richard
BP> Freeborn at Kensa argues. In fact, he had some justification for why
his
BP> kit was no more expensive than a boiler, though I struggle to see
how
BP> that is not an exaggeration.

Thanks for the link, interesting to get upto date info on heat pumps.

Unfortunately that site rather confirms my assertion that you will
never recoup your capital outlay on these systems.

Currently my house is heated with an oil fired boiler with an output
of 17kW. Its getting on, so I'm thinking of replacing it. Looking at
the SEDBUK site the most efficient boilers are from Grant. A suitable
model is the Vortex 15kW, costing about £1300. Looking at the Kensa
list, the most suitable heat pump gives a nominal output of 14KW;
unfortunately this pump costs £5230 + VAT, a total of £6145. Take off
your £1200 grant leaving a cost of £4945. But its going to cost a lot
more to have someone install a heat pump, 'cos someones got to dig a
big hole in the ground to bury the heat collecting pipe. I would guess
that this would cost in the region of £2000. This gets you to a total
capital outlay of £6945. Take off the boiler price leaving you with an
excess capital outlay of £5445.

I spend about £400 p.a. on oil. Even if you pay nothing for your fuel
it will take nearly 14 years to recover your capital costs. If you
take the efficiency that Kensa give (a ludicrously optimistic figure)
you will get 4kw out of the heat pump for 1kw input. If you pay 5p per
unit that gives you a cost of 1.25p per unit of heat delivered.
Currently oil is about 16.5p per litre, which works out at about 1.9p
per unit of heat delivered, assuming 90% efficiency (the best boilers
are about 97% efficient). On the basis of 30Kw p.a. heat used this
gives an advantage in running costs of about £190 p.a. to the heat
pump. On this basis it will take 26 years to recover the capital
costs. If you use a more realistic, but still optimistic, figure for
efficincy of 3kw out per 1 kw in you get to a saving of £80 p.a. which
will take you 78 years to recover.

In fact these are simplistic figures which exclude things like loss of
interest on capital, so they are biased in favour of the heat pump.

I see that you are using LPG for your main heating system. As this is
the most expensive fuel available (apart from peak rate electricity) a
comparison is likely to favour a heat pump more; but then you can't
take the boiler price off your capital costs so the repayment period
is still likely to be large.

Heat pumps may become economically viable if fuel prices rise
significantly; I believe in the 70s they made sense; but at the
moment, with rock bottom fuel prices I am afraid that they don't.

There may be good reasons for installing a heat pump; economics is not
one of them.

Bill