This one is driving me mad.
Water was dripping outside through the discharge pipe, so checked the boiler pressure guage and it was indicating 3.5 bar! (Well over the 3 bar maximum) Initially suspected the Pressure Reducing Valve. It was looking wet also. Pulled the cartridge out and it was in a bad shape internally. Fitted a new one after cleaning out the valve casing. Repressurised the system checking the external expansion vessel had 3.5 bar of air pressure inside, as stipulated. Pressure rose again to 3.5 bar inside the boiler without turning on the boiler (i.e. water still cold) !! Grrr
Next thing, is the filling loop small isolating valve damaged as this was still connected? On disconnecting it, noticed that non-return valve was leaking slightly and some water exiting the boiler, but no sign of water passing the isolating valve into the boiler. Changed the NRV anyway and fitted a new filling loop and isolating valve as I had one.
Repressurised the boiler to 1.5 bar, shut the filling loop valve, disconnected the filling loop braided pipe and pressure again rises slowly to 3.5 bar!! Grrr
Checked the boiler safety valve and this is functioning correctly. Quarter turn and it dumps water and pressure quickly through the discharge pipe. Leave it to opperate normally and at 3 bar, it opens slightly releasing pressure to a drip, drip, drip outside through the discharge pipe. This suggests the pressure is building slowly somehow.
So how can the system be repressurising with the filling loop disconnected? The mains pressure is higher than 3.5 bar, but the cold water feed has the pressure reducing valve to limit the pressure to 3.5 bar. Ironically, this is roughly what the boiler guage is reading.
How can water enter the heating circuit with the filling loop disconected?
Could the Vaillant Vantage 120/150/200 cylinder have a cracked coil and water is entering the boiler circuit from the hot water side? If so, how can I test this and more importantly, can these be repaired? They are the best part of £700 to buy and I don't think they make these models any more!
Any advice appreciated.
Chris
P.s. The boiler is a Vaillant Thermocompact VU GB 282-5
Water was dripping outside through the discharge pipe, so checked the boiler pressure guage and it was indicating 3.5 bar! (Well over the 3 bar maximum) Initially suspected the Pressure Reducing Valve. It was looking wet also. Pulled the cartridge out and it was in a bad shape internally. Fitted a new one after cleaning out the valve casing. Repressurised the system checking the external expansion vessel had 3.5 bar of air pressure inside, as stipulated. Pressure rose again to 3.5 bar inside the boiler without turning on the boiler (i.e. water still cold) !! Grrr
Next thing, is the filling loop small isolating valve damaged as this was still connected? On disconnecting it, noticed that non-return valve was leaking slightly and some water exiting the boiler, but no sign of water passing the isolating valve into the boiler. Changed the NRV anyway and fitted a new filling loop and isolating valve as I had one.
Repressurised the boiler to 1.5 bar, shut the filling loop valve, disconnected the filling loop braided pipe and pressure again rises slowly to 3.5 bar!! Grrr
Checked the boiler safety valve and this is functioning correctly. Quarter turn and it dumps water and pressure quickly through the discharge pipe. Leave it to opperate normally and at 3 bar, it opens slightly releasing pressure to a drip, drip, drip outside through the discharge pipe. This suggests the pressure is building slowly somehow.
So how can the system be repressurising with the filling loop disconnected? The mains pressure is higher than 3.5 bar, but the cold water feed has the pressure reducing valve to limit the pressure to 3.5 bar. Ironically, this is roughly what the boiler guage is reading.
How can water enter the heating circuit with the filling loop disconected?
Could the Vaillant Vantage 120/150/200 cylinder have a cracked coil and water is entering the boiler circuit from the hot water side? If so, how can I test this and more importantly, can these be repaired? They are the best part of £700 to buy and I don't think they make these models any more!
Any advice appreciated.
Chris
P.s. The boiler is a Vaillant Thermocompact VU GB 282-5