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]

Does the inlet pressure drop when it attempts to ignite? GV getting correct voltage? Have you checked resistance of GV? Smart meter? Credit meter? Any other gas appliances? - if yes, have you checked these?

 

[Sandeep89]

Does the inlet pressure drop when it attempts to ignite? GV getting correct voltage? Have you checked resistance of GV? Smart meter? Credit meter? Any other gas appliances? - if yes, have you checked these?

Hi

So inlet pressure does not drop when attempting to ignite.

They have another boiler inside the house along with a gas hob which are both working fine.

 

[Deleted member 120897]

Check resistance of GV, voltages, if they’re ok, I’d suggest replacement GV.

 

[Sandeep89]

Check resistance of GV, voltages, if they’re ok, I’d suggest replacement GV.

Thanks, I will have a look. Do you know were I can find what resistance the GV should be.

 

[ShaunCorbs]

Does anything happen sounds like pcb if it’s stuck

 

[Deleted member 120897]

Thanks, I will have a look. Do you know were I can find what resistance the GV should be.

Mi’s/technical helpline.

 

[Sandeep89]

Does anything happen sounds like pcb if it’s stuck

I can't hear the gas valve clunk or any sounds of it opening.

All customer has said they had a gas leak which was repaired as soon as the leak was fixed and boiler was turned on flame failure started flashing straight away.

Prior to the gas leak being fixed boiler was working fine. I had a look at the MI and it states the flame failure flashing slow is pump issue or internal fault.

I removed the bleed screw on pump and the pump is spinning.

 

[ShaunCorbs]

Fan spinning ?

 

[Sandeep89]

Fan spinning ?

Fan only spins when I make manual contact to the heating/pump proving microswitch, when contact to this is made the boiler reaches spark stage.

When hot water tap is opened pin pushes out to make contact to the microswitch at the front but fan does not kick in.

When heating is turned on the heating pin at top does not push out at all.

 

[ShaunCorbs]

Pump or heating diaphragm need looking at as when the pump is running the heating pin should make contact with the micro switch

 

[Sandeep89]

Pump or heating diaphragm need looking at as when the pump is running the heating pin should make contact with the micro switch

Thanks. I'm back there tomorrow so will have a look

 

[Sandeep89]

Pump or heating diaphragm need looking at as when the pump is running the heating pin should make contact with the micro switch

I removed the bleed screw from the pump whilst the pump was on and the pun internally is spinning.

 

[ShaunCorbs]

Looks like you might need a service kit

Pardon our interruption...

 

[Sandeep89]

Looks like you might need a service kit

Pardon our interruption...

Thanks.

Will look into it

 

[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?