Dave Liquorice wrote:
On Thu, 10 Sep 2009 10:17:20 +0100, The Natural Philosopher wrote:

I've got a 12 KW boiler, so it fires up for just ten minutes a day to
heat the tank.

Small boiler, ours is 38kW and that can struggle to keep this place
warm when the wind is up and the temperature down.

My oil bill is about £2000 a year of which about £1300 is in December
January and February. The rest is in the spring and autumn, and in
summer,(June July and August) it uses almost nothing.

I'm surprised a 12kW boiler can burn that much oil. B-)

in really cold weather, it stays on continuously. The rated heatloss at
20c interior and -5C exterior is 10Kw. the mass of the flooring screed
means that that carries us through the peaks BUT when its that cold, it
is not possible to e.g. switch it off at night and expect it to be warm
in the mornings.

Taking oil at around 5p/kilowatt hour, and maybe 7.5p in terms of
useable output, that mens we are probably using an average of 8KW over
the winter, day in and day out.


Actually I think exaggerated..at todays oil prices its more like 700
over the winter 3, and 700 for the rest of the year combined ..

So about 4.5 KW average. Thats sounds more like it, as teh duty cycle
varies from 'that boiler has been on continously for two hoursm, and its
just cut off for 25 minutes and now its on;' to 'the boiler seems to be
on for 20 minutes and then off for 20 minutes'


We get
through 4000l/year, so depending on the price anything from £2000
down to £1200 a year. And yes it is space heating that gobbles the
oil up; more or less 25l/day in the winter and 25/lweek in the
summer.

So get a bigger tank and fit an immersion heater.

A bigger tank in the form a heat store/bank is on the cards to go
with the wood burner and once that is in solar panels may as well be
added.

I had toyed with the idea of a windmill and dumping any excess into
the heatbank before selling to the grid. That was before I plotted
estimated power generation v useage the other day. A fairly windy day
with the 6kW unit producing full output for several hours did produce
a significant surplus (50kWHrs, about 2 1/2 days consumption) but
since then (the 8th) it's been calm... The 2.5kW unit would struggle
to meet our base load most of the time let alone generate a surplus
to be dumped into the heat bank or sold.



exactly. I think I worked out my average total power consumption was
3Kw. Varying from about 300-400W in summer, to 12Kw in winter.

The overwhelming cost is winter space heating.

Currently the cheapest way is oil (no gas) , and whatever free wood I
can acquire. Wood is not a lot different to oil at the moment!
But if I were doing it again, its fractionally cheaper to use a
heatpump. More so as oil rises over $55 a barrel, which is the sort of
breakeven point.

The lowest carbon way of heating it is definitely a heatpump and a
nuclear power station. Fortunately there is one down the road ..

As I have said many times and oft, there are only two techniologies that
really deliver a lower carbon foot[rint - nuclear power and heat pumps.
Everything else is impractical expensive and unreliable.