Main Combi 24 HE Flame Failure

[Sandeep89]

Hi Guys,

Got a Main Combi 24 HE which is stuck on flame failure. Customer had a gas leak on the gas run which was repaired, after this the customer turned the boiler on from the spur and the boiler is was stuck on flame failure which flashes slowly.

When hot water demand is given the pin hits the microswitch but boiler does not go through sequence. When heating demand is given the pin does not push out to hit microswitch, however I made manual contact to the heating switch and the boiler sparks but does not ignite and locks out.

I have checked pump by removing the bleed scre and pump is spinning, checked gas valve and getting 23mbar on p1.

Can anyone give me further guidance as customer is saying it only started with flame failure after gas leak was fixed. All gas isolation valves are open.

Thanks

 

[Deleted member 120897]

Would a diverter not making cause lockout though?

 

[ShaunCorbs]

Would a diverter not making cause lockout though?

Not sensing pump is spinning it’s a pump proving like the vaillants using the pressure sensor to check there’s an increase when the pump is on

 

[Sandeep89]

Not sensing pump is spinning it’s a pump proving like the vaillants using the pressure sensor to check there’s an increase when the pump is on

Hi,

Come back here this morning turned heating on and pin still did not come out to make connection to pump proving switch. I made manual contact to switch and the burner ignited. Boiler ran for around 2-3 mins and then burner cut out and flame failure started flashing again.

Does it seem to be an issue with the pump. I am getting 230v at pump.

 

[Deleted member 120897]

230 volts at pump means just that you‘re getting voltage. Does it spin, can you stop it with a screwdriver? Seems like it’s possibly not rectifying?

 

[Sandeep89]

230 volts at pump means just that you‘re getting voltage. Does it spin, can you stop it with a screwdriver? Seems like it’s possibly not rectifying?

Pump spins, and can be stopped with screwdriver.

 

[Deleted member 120897]

Pump spins, and can be stopped with screwdriver.

Might be weak pump then, shouldn’t be able to stop pump with screwdriver unless your applying quite some force?

 

[Sandeep89]

Might be weak pump then, shouldn’t be able to stop pump with screwdriver unless your applying quite some force?

I didn't have to use much force at all. I could hear the pump making some ticking, very light grinding noise aswell. Had a look in MIs again last night which showed pump fault as well. Will do some more checks. Thanks for the help.

 

[ShaunCorbs]

Sounds like pump

 

[Sandeep89]

Hi Guys,

So replaced pump and both dhw and pump proving heating diagphrams.

The back pump proving pin still won't come out to make contact with the switch.

However if I make manual contact to switch burner fires up both on ch and hw.

Could it be a faulty diverter valve.

 

[Deleted member 120897]

Did you grease the spindle when replacing the diaphragm?

 

[Sandeep89]

Did you grease the spindle when replacing the diaphragm?

Yeah all greased up. Spoke to Main technical helpline who are saying as the boiler has been sitting idle for a long time the bypass pipe at the back may be blocked.

So that is next step they are saying to look into that.

 

[ShaunCorbs]

Also check the little 4-6mm pigs tail tube