I know nothing about central heating so please don't flame me.
We have a small annexe over our garage which is not being used at the
moment. I want to set the heating system up so that it uses the least amount
of energy while protecting the pipes from freezing, is that necessary?
The system comprises a 'Worcester 240' boiler which heats the hot water and
feeds 3 radiators. All of the radiators have thermostatic controls fitted
but I am not sure what to set them to, to avoid frozen pipes.
I have some questions I was hoping you could help me with:
1. I was going to set the thermostats on all three radiators to the 'blue
snowflake' setting which is the setting below a single red line, Is this
right? My only concern is that when I set it to the blue snowflake (on all
three radiators) it seems to cut off all the water (perhaps some is still
flowing but I can't tell). If I turn the thermostat up to the mid point
halfway between the blue snowflake and the single red line, I can hear water
start to flow and the radiator gets quite hot but that seems to be too hot.
2. I was going to set the boiler thermostat to the minimum setting. Is this
right? This article
on the Powergen website suggests that the boiler works most efficiently when
set to high but I only want to heat a little water to stop the pipes
freezing so I'm not sure what to do for the best.
3. Do I need to turn the hot water setting on to protect the pipes?
4. If I can figure out how to program the boiler, is there a recommended
time when you should switch the boiler on over night to stop pipes freezing?
Say 10PM - 8AM or something like that.
5. If I can't figure out how to program the boiler is it OK/economic to
leave the boiler switched to the ON position for the next few months?
Hope I made some sense.
Thanks for any help.
Yes, but check your insurance. You may find you are not covered
for burst pipes unless the premises is frequently checked.
Draining down maybe another option, but rather few systems are
designed so they can be completely drained down (and this is not
just the heating system, but all the supply pipework too).
That article is too simplistic to hold any validity -- ignore it.
In any case, it isn't talking about frost protection setup.
You should get an electrician to fit a frost stat (which shouldn't cost
much), and then leave the boiler on 24 hours, with the thermostatic
radiator valves in their normal positions and the boiler temperature
set to minimum, with the frost stat controlling the system. The frost
stat should be put in the place most likely to be the coldest in the
building, but where it isn't going to be directly heated by a radiator
or any associated pipework. Set it to something like 6C, or for an old
building with solid walls, you might need to go up higher to prevent
a damp smell. Any pipework running through unheated areas of the
building must be well lagged.
This will be our last winter in the house and money is tight so we don't
want to go to the expense of fitting a room thermostat if possible although
it is a good idea.
I set the boiler temperature to minimum and the 3 radiators to the 'blue
snowflake' setting aboy 4-5 hours ago. Now I have a few more questions:
1. The boiler seems to be going crazy switching on and off every few
minutes, is this normal for my settings?
2. Despite the radiators being set to 'blue snowflake' setting 4-5 hours
ago. I just checked and two of the radiators are so hot you would not want
to touch them for long and one of them is luke warm, is this right? I would
have thought they would get just warm enough to stave of freezing pipes
rather than a heat up really hot / cool down cycle. Could someone confirm
what should happen? (present conditions are very cold in the rooms).
3. I bled all the radiators, one of the radiators had a lot of air in it but
I expect they have not been bled for a long, long time. Am I ok to do this
as I assume this is a closed system.
4. The pressure is about .75 bar, is about right for the above mentioned
Thanks for all your help
Yes -- you need a room stat (or frost stat) to prevent the boiler
firing up when there's no requirement for heat from the radiators.
Otherwise, the boiler will just be keeping the bypass loop up to
temperature, which is going to result in frequent switching on and
off. (For this reason, boilers fitted nowadays _have_ to include
some mechanism such as a room stat to switch them off when there's
no call for heat, to avoid wasting this energy.)
You might find it cheaper to get a room/frost stat fitted, than
paying for this energy usage and possibly a replacement gas valve
or igniter, or whatever part of the boiler wears out faster as a
Oh, and I'm assuming the boiler does have a bypass. If not, then
you should have one radiator with no TRV or other means of closing
What are the temperatures in those rooms?
Yes, I would expect the radiators to be hot at the top, as they
will have the full temperature boiler water there. Unless your
boiler is a condensing boiler, the minimum flow temperature is
probably something like 70C. However, if the TRV has reduced the
flow to a minimum, you'll find the radiators get cold as you run
your hand down to the bottom, because the flow in the radiators
is tiny. This is how the TRV reduces the heat output from radiators.
Pressure would typically be about 1 bar when cold (and it goes up
when the system gets hot, but probably not by much in such a small
system). The .75 bar will drop when the radiators are cold, and
there's a risk it might drop below the point where the boiler will
operate (assuming your boiler has a pressure sensor switch).
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