Please Help ! My Vaillant 242 EH is giving problems again. HW works well. When CH switched on fires and rums well until rads are warm. After the first cooling period it tries to fire up, up to 25 times but the flame does not catch on and stay and after 25 attempts the lock out jumps out. Noticed that pressure drops and needs refilling (for 30 seconds) often through the loop. Pump replaced two years back and running ok, no leaks in the heat exchanger. Did some work 3 years back with your help and happy to handle any thing mechanical. Thank you.
Vaillant VCW GB 242 EH ch problem
- Thread starter Don2
- Start date
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is the pressure rising to 3 when heating on then dropping?
it wont fire if the pressure is low
it wont fire if the pressure is low
Thank you for the reply, please bear with my detailed answer.
Yes, This morning it would not fire for hot water and found the pressure was at less than zero (pointer resting on the bottom support)(no leaks from pressure release valve and found a leak of about 3 to 4 drops per minute from the system drain outside and stopped by tightening) . Raised the pressure to 1.4 bar and tried fired for hot water, fired ok, then whilst hot water was drawn switched on the CH (even without hot water been drawn it fires for CH ok when starting from cold if the pressure is around 1.4). Say 15 mts later I was told that the cut out switch had jumped out. I then pushed the switch in and stayed with the boiler to watch the sequence.
Fired after several attempts on CH and stayed for about 18 mts till the pressure reached 3 and temperature to 73 and flame went off. After 8 mts of resting it tried to fire when the pressure had dropped to 2 bar and temp to 60, tried for about 20 to 25 times, the flame failed to catch on and tripped the cut off switch off again.
After 30 mts the pressure had come to zero and temp down to 40, pushed the cut out trip in, trued to fire for 22 times, failed and tripped again.
Increased the pressure to 1.2 through the loop and pushed the trip in fired and flame held after 4 attempts. stayed on for 15 mts pressure went up to 4 and slightly over (out of the scale)and temp up to 70. I then bled the rads pressure came down to 3.8 and system went to rest after reaching 72c.
After the cooling period pressure came down to 0.6 bar and temp down to 60 and it tried to fire but the flame did not stay. I then increased the pressure to 1.4bar and fired OK on the 4th attempt.
Is it dangerous to reach 4 bar ? at what pressure should Pressure Release Valve open ? How to cure the problem of firing after the rest period due to pressure fluctuation /
Many thanks for your patience and advice
Yes, This morning it would not fire for hot water and found the pressure was at less than zero (pointer resting on the bottom support)(no leaks from pressure release valve and found a leak of about 3 to 4 drops per minute from the system drain outside and stopped by tightening) . Raised the pressure to 1.4 bar and tried fired for hot water, fired ok, then whilst hot water was drawn switched on the CH (even without hot water been drawn it fires for CH ok when starting from cold if the pressure is around 1.4). Say 15 mts later I was told that the cut out switch had jumped out. I then pushed the switch in and stayed with the boiler to watch the sequence.
Fired after several attempts on CH and stayed for about 18 mts till the pressure reached 3 and temperature to 73 and flame went off. After 8 mts of resting it tried to fire when the pressure had dropped to 2 bar and temp to 60, tried for about 20 to 25 times, the flame failed to catch on and tripped the cut off switch off again.
After 30 mts the pressure had come to zero and temp down to 40, pushed the cut out trip in, trued to fire for 22 times, failed and tripped again.
Increased the pressure to 1.2 through the loop and pushed the trip in fired and flame held after 4 attempts. stayed on for 15 mts pressure went up to 4 and slightly over (out of the scale)and temp up to 70. I then bled the rads pressure came down to 3.8 and system went to rest after reaching 72c.
After the cooling period pressure came down to 0.6 bar and temp down to 60 and it tried to fire but the flame did not stay. I then increased the pressure to 1.4bar and fired OK on the 4th attempt.
Is it dangerous to reach 4 bar ? at what pressure should Pressure Release Valve open ? How to cure the problem of firing after the rest period due to pressure fluctuation /
Many thanks for your patience and advice
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Thank you , Bingo Bongo, Agile and do it all.
I shall replace the pressure relief valve and pressurise the CH expansion vessel. The manual says to check the pressure and if low to pressurise to 0.7 to 0.9 bar with a air pump (presume a foot pump will do). Could any body shed some light on where I could find a suitable pressure guage (meeter) to check the vessel. Many thanks.
I shall replace the pressure relief valve and pressurise the CH expansion vessel. The manual says to check the pressure and if low to pressurise to 0.7 to 0.9 bar with a air pump (presume a foot pump will do). Could any body shed some light on where I could find a suitable pressure guage (meeter) to check the vessel. Many thanks.
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