It is not clear from FAQ EXV DIY when to test the pressure hot or cold, it just says turm the boiler off at the mains.
Vaillant VCW221 Problem - time/delay cycle on CH
- Thread starter mcaroon
- Start date
Seems fairly clear to me!
Press the central pin. If water comes out you need a new Pressure Vessel
Drain enough water from the heating system via a drain cock, to allow the pressure gauge to drop to Zero. Measure the air pressure in the EXV.
If its below about 9 psi then it needs repressurising!
Leave the drain cock open.
Use any (car or bike)air pump with a built-in gauge to pump up the PV to eg (See Boiler Instructions) 10 psi (0.7 bar). This pressure isn't too critical, and it will as you have found drop over time.
Remove and refit the pump to see how much the pressure drops when you remove it and inevitably lose some air.
If the pump doesn't have a built in gauge, pump it up a bit high, then keep taking readings with a push-on gauge. Every time you do, the pressure will drop a bit.
During this phase it is IMPERATIVE that water or air is allowed to escape from the heating system as it is pumped out of the PV. Otherwise the system pressure will resist your pumping and give a meaningless reading. If you aren't sure, let some more water out when you have the air pressure at the right level. If that makes the air pressure drop, pump a bit more and release water and so on, until it doesn't.
Press the central pin. If water comes out you need a new Pressure Vessel
Drain enough water from the heating system via a drain cock, to allow the pressure gauge to drop to Zero. Measure the air pressure in the EXV.
If its below about 9 psi then it needs repressurising!
Leave the drain cock open.
Use any (car or bike)air pump with a built-in gauge to pump up the PV to eg (See Boiler Instructions) 10 psi (0.7 bar). This pressure isn't too critical, and it will as you have found drop over time.
Remove and refit the pump to see how much the pressure drops when you remove it and inevitably lose some air.
If the pump doesn't have a built in gauge, pump it up a bit high, then keep taking readings with a push-on gauge. Every time you do, the pressure will drop a bit.
During this phase it is IMPERATIVE that water or air is allowed to escape from the heating system as it is pumped out of the PV. Otherwise the system pressure will resist your pumping and give a meaningless reading. If you aren't sure, let some more water out when you have the air pressure at the right level. If that makes the air pressure drop, pump a bit more and release water and so on, until it doesn't.
There was absolutely NO PRESSURE in the EXV (External Vessel), i don't think it has ever been pressurized.
Set pressure to 1bar in EXV and then on the dial, and switched the CH and pressure hardly goes past 2bar, and no leak at all.
Was dreading the worse (replacing the EXV) which would have a monumental task, or putting the boiler to sleep.
Thanks for all the help Tony saved me few pennies.
Set pressure to 1bar in EXV and then on the dial, and switched the CH and pressure hardly goes past 2bar, and no leak at all.
Was dreading the worse (replacing the EXV) which would have a monumental task, or putting the boiler to sleep.
Thanks for all the help Tony saved me few pennies.
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