Loss of Pressure in C/H system

[candyjet]

Over the last 24 hours our C/H system has lost pressure. I can top up the pressure using 2 small taps which are close to a pressure gauge, and I increase the pressure to 1 bar.

The system then loses pressure over a few minutes, the radiators make splashing noises and the pressure is soon back to zero.

Reading this forum, I wonder if it is an expansion vessel problem, the vessel is about 5 years old.

My question is this; what are the controls on the vessel for?

There is a red tap on the vessel with an anticlockwise arrow and '3 bar' written on it. Will this have any effect?

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• candyjet
• 14 Nov 2010
• 1

Secondly, there is the car type valve on the bottom, which when pressed gives out air, not water.

Is there anything I can do with these controls to rectify the problem?

The pressure gauge is upstairs, far away from the vessel.

Thanks

CJ

 

[ianniann]

Nobody?

An expansion vessel problem (other than having a big hole in it!) usually refers to one that has lost its pressurisation and the symptoms would be very high pressure when the central heating was on, sometimes leading to loss of water from any pressure relief valve. The pressure with the system off may be normal for a minor problem or low if you have lost water. Refilling will give you a normal pressure again until you turn on the heating, then it will rise and possible overflow again.

Your problem sounds like a simple leak. You put water in, and shortly afterwards there is no water again. There will be a puddle somewhere

 

[candyjet]

Thanks, ianniann,

I am coming to that conclusion, were it not for the lack of a puddle.

It has been suggested that the coil inside the hot water tank could be leaking into the tank and this is the source of the hidden leak.

If so, how could this be diagnosed, other than repacing the tank?

Thanks again

CJ

 

[gavinda]

from the valve with the red handle (pressure relief valve) check the pipe leading from it to outside and make sure it is not discharging water. if it is you expansion vessel may have failed and need recharging/replacing.


to prove the coil on your cylinder 1st identify the feed to the cylinder from your cold water tank by running the bath hot tap and feeling for suction in the cold tank. once identified have someone turn on the filling loop for your heating system and feel if water is puched up the col feed from the cylinder.