Velvet wrote:


I'm still really looking for a fairly simple explanation of the energy
used to heat a place from a colder temp, vs energy used to maintain a
temp. Someone somewhere must have done the research for this, I just
can't find it :-) I thought maybe there were lurking people here who
had the physics etc knowledge to calculate this sort of thing, I was
thinking it was something that people might know from sizing CH systems
since you have to generate enough heat to actually get the place warmed
up in the morning, but I think I'm realising that the efficiency isn't
looked at in an overall sense like this but more as an 'insulate as much
as possible then fit the most efficient boiler' - just seems there's a
bit bit of the puzzle being missed out, which is how to run the CH most
efficiently.

Off to google again for more physics based stuff I think!




Heat required is the integral of temperature difference times the
calculated U values over the surface areas of the house PLUS the amount
of heat needed to raise the temperature of teh contained air mass and
structure to the same level.

However this is a 'once and only' heat 'loss' since once warm. it takes
no extra heat to keep it warm - its all about the insulation and air
change losses. And if you like it gives it back to you by staying warm
after the heating goes off.

The pertinent issue is whether you need to e.g. raise air temperature
significanbtly MORE to feel confortable in a room with a stone cold
concrete floor and icy thick exposed brickwork etc. etc.

The 'tmed' soulktion is most effective where heat loss is high and
thermal mass low. There there is very little retention of heat, and teh
internal temperature responds rapidly to CH heat input.

If insulation and mass is high, the system takes longer to respond if
driven by the rated boler outpurt, since this will be lower anyway due
to teh better insulation. In effect, it will take time to get up to
temperarture, teh boiler will run at peak output for a lomngish initial
period, and the rooms may need to be set hotter in order not to feel
cold until it does.

There are so many variables that its very hard to predict, but having
moved fom only moderately well nsulated house to one with big mases and
good insulation, the oil burn rate is very little extra on 24 hour
heating on the UF sections.

Upstairs where its studwork walls only, its timed, and these warm up
very quickly anyway.






Velvet