the pressure drops overnight to zero when the boilers not in use , its ok when its running. ravenheat c85t condensing boiler , also which is a different issue the hot water goes cold for approx 10 secs then comes back warm again repeatedly , any help appreciated , tim.
Pressure drops rapidly when boiler off
- Thread starter timritaharry
- Start date
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Is it...
On 1.5bar, then you turn the heating on and the pressure rises, then when the central heating is turned off and system is cold, it drops to 0bar.
or...
Pressure is on 0bar when you turn the sytem on, pressure rises, then goes back to 0bar when you turn it off.
On 1.5bar, then you turn the heating on and the pressure rises, then when the central heating is turned off and system is cold, it drops to 0bar.
or...
Pressure is on 0bar when you turn the sytem on, pressure rises, then goes back to 0bar when you turn it off.
hi, after the boilers been running i turn it off for the night and the pressure drops to zero overnight, it wont start up again till ive filled it back up again with the filling loop , once its running its ok ,its only when i turn it off that it gradually drops, this happens every day ! thanks, tim
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hi ,it rises and stops at a stable pressure
Rises to 
if i fill it to 1.5 bar as soon as it fires up it drops to 1.4 bar then gradually rises to no more than 1.8 bar till boiler reaches set temp then drops very slightly till boiler fires up again.
Does the safety release pipe drip outside?
Otherwise there will be a leak under the floor.
Otherwise there will be a leak under the floor.
just checked and the safety relief valve seems to be leaking all the time small amounts !
There's your problem.
so i need a new safety release valve ?
If accessible, the pressure relief valve will have a test knob or lever. Operating this device quickly a few times will let some water through, and with luck the valve will seat properly.
Normally it's not recommended to use the test device as it can cause the valve to leak when particles in the water get trapped in it. As yours is leaking anyway, it may be worth a go, before replacing it.
Once you've either got the valve closed or a new one fitted, you should add corrosion inhibitor to the system water as the existing inhibitor will have been diluted by all the fresh water you've b een letting in.
ok , thanks for that will try like you said and if not will try a new valve.
any ideas as to whythe hot water works ok then keeps going cold for about 10 secs then fires up again and so on ?
thanks again, tim
any ideas as to whythe hot water works ok then keeps going cold for about 10 secs then fires up again and so on ?
thanks again, tim
Scaled hot water heat exchanger.
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