On Fri, 16 Jan 2004 16:47:55 +0000 (GMT), "Dave Liquorice"
wrote:


-44C blooming cold... Even on a very cold night for the UK say -10C
you still have 30+C of temperature gradient to push heat into the
cylinder.

My daughter tells me it is -22C at the moment :-)

This is of course highly dependant on the size of the engine,

Very much so but I think for the sizes we are talking, max of 5kVA
genset, running at an average of 20% capacity I doubt it is of
practical concern.

I agree, which is why I posted it is about the same as a couple of
hobs full on, bear in mine it becomes more of a problem as the bottles
empty.

Slightly related is that it is, allegedly, known for lpg equipped
vehicles with no antifreeze in the coolant to freeze their vapourisers
before the thermostat opens, bringing the vehicle to a halt.

I choose 1kVA as an average with care, that is pretty much what our
daily average load is. Though that includes when we are all asleep, so
I guess the "active" average load might be as much as 2kVA.

This accords with what I found with our genset, though this is not
domestic use.

I think you are mixing the terminology a bit here, OK the genset needs
to know the kVA, because if either current or Volts exceed the rating
of the machine something gives (after allowing a safety margin) but it
is the kW draw that determines the heat load of the engine ( and
indeed whether it stalls). So you may have a 10kVA genset capable of
supplying 7.5kW(e) continuously but working on average at 2kW(e). In
point of fact this is what makes permanent magnet alternators and
inverters so interesting to me for home use (once demand shifts from
90%heat:10%electricty to something nearer 70%heat:30% electricity)

AJH