In an earlier contribution to this discussion,
Golan wrote:

I tried to look in old post but can't find any information so I am
asking.

At this time of the year I am turning on the heating in my flat only
for couple of hour's in the bath room. All the radiators in the flat
are off.

The pressure on the boiler is low than normal about 0.7.
I know that when the hating is on it needs to be around 1.5 but isn't
the fact that only on radiator is on actually mean less hot water in
the system and there for less extract which mean lower pressure ? If I
top up the system and open more radiators the pressure goes very high
2.5.

Thank you for any information

From distilling numerous previous threads, the 'norm' seems to be 1 bar when
cold and 2 bar when hot.

The pressure rise is due to the fact that the water in the system expands
when it gets hot and compresses the gas in the expansion vessel, with a
consequent increase in pressure. If only *some* of the water is getting hot
(the remainder being in unheated radiators and pipes) the pressure rise will
be lower. What you are experiencing seems fairly normal - except that 0.7
bar sounds a bit low. Is that cold or (partially) hot?
--
Cheers,
Roger
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