On 2006-10-15 08:28:14 +0100, manxtatt2 said:


Any help on this matter greatly apprecaited

We have just moved into a 3 storey house , that has gas central heating
boiler.

What is the ideal temp in 0c to operate this to heat the house.

weve been told different things by people we know , but im still
unsure.

I think that around 75 or 80c is right , yet someone else says 50c

also what would be ideal times for setting heating to ?? is is ideal
to have it on for say 2 hrs in am , and 2 hours at night , does that
use up more gas, or have it on for longer
Any advice??

Simon

This depends on the boiler and radiators.

If you have a conventional heating boiler, it should be run at its
design temperature, which is around 80 degrees on the flow side.
If it is run a lot cooler than that, there is a risk of condensation of
flue products inside the boiler and consequent corrosion. Generally
the boiler thermostat should not allow setting to temperatures low
enough to cause a problem, but certainly 50 degrees or even 60 flow
would take you to the point of internal condensation.

There is a newer type of boiler (condensing), which is now more or less
mandatory to fit unless you have particularly unusual set of
installation conditions. These can be 30% or so more efficient than
some of the oldest conventional boilers and there is legislation on
fitting them in new or replacement installations except in exceptional
cases.
In this type, the intention is that condensing does take place in the
boiler, and the water is collected and fed to a drain. While these
will work at the higher temperatures of the conventional boiler, they
run more efficiently at lower temperatures.

However, if your system was originally designed for a conventional
boiler, it is likely that the radiators will have been sized for 80
degree operation and 0 or -3 degrees outside. Unless they were
oversized, running at 50 degrees may not give enough heat output in
cold weather. This still means that a condensing boiler is worthwhile
because for most of the year that level of heat output is not required
and the boiler can run at a lower temperature and hence more efficiently

The other factor in low temperature operation would be that it would
take longer to warm the house if it's really cold outside if radiators
are run at 50 vs 80 degrees.

Switch on and running times are a personal choice. Of course running
for longer uses more fuel, the other side of the coin is level of
comfort.

One thing that you can do is to change the room thermostat for one with
optimised start and perhaps night setback.

Optimised start is basically that the thermostat monitors how long it
takes the heating system to raise the house temperature to the point
you set. This is averaged over a few days. So for example, if you
want it to be up to temperature at 0700 when you get up, it might need
to start at 0615 on a cold day and so on.

Night set back means that instead of turning off the heating totally at
night, it backs off the temperature by a few degrees. For example, you
might set a setback of 6 or 7 degrees against a desired room
temperature of 21 degrees and allow the temperature to fall to 14 or 15
during the night. Through much of the year, this doesn't use any or
much extra energy, but in the coldest weather is pleasant if you need
to get up during the night. Also, in some houses, it may actually
prevent the temperature overshooting the set point by as much on the
morning warm up and hence actually save fuel use overall.

If you don't have them, a useful investment is thermostatic radiator
valves on the room radiators (all but the one where the room thermostat
is). These allow finer control of room temperature and save fuel as
well.