Ideal Classic FF280 not cross firing

[n4nlm]

Hi

My trusty old Classic FF280 has stopped cross firing from pilot to main burner. The pilot light lights and stays lit. The fan is fully operational. The fault finding guide leads to a faulty gas valve. This also seems to be the diagnosis from checking the forum. Please can anyone confirm the diagnosis, could the pcb or the air pressure sensor also be the cause of the fault? I don't want to miss checking something, I need to get an engineer to fix asap and will order parts in advance of visit to help speed up the process.

I am also curious as to the mechanics of the valve and signals from the pcb. If the pcb has sent a signal to light the pilot, how does 1) the pcb identify the pilot is lit and 2) then advise the gas valve to send gas to the main burner? There is only one set of wires from the pcb to the gas valve that connects the pilot solenoid and to main gas valve via a bridged connector. There is power at both terminals of the bridge connector. There is a black wire in addition to the live and neutral wires, perhaps this provides a trigger for the main burner?

One last observation, the boiler used to fire up with a 'bang' rather than a smooth gradual flame increase. Maybe this gives a further clue to the cause of the problem.

Thank you in advance for your answers. Nicholas.

 

[jeff the gasman]

As it’s gas related we are not allowed to advise you but a Gas registered installer will know.

 

[n4nlm]

Thank you for your reply. I am naturally disappointed with the 'it's gas, can't say' response since there are other similar questions on the site that get more comprehensive answers. Still interested to know how things work, if anyone is willing to explain.

 

[ianmcd]

Hi Nicholas
Unfortunately it is the site rules that state this and quite rightly so, I can however tell you how things work,when there is a call for heat the boiler goes through a few sequences but they are fine as the pilot is establishing ,when the pilot is established, the spark/sensing electrode sends a signal to the PCB, this in turn sends voltage to the main solenoid on the gas valve and it opens, then the main burner comes on, the gas valve has 2 solenoids the round one is for the pilot light and the larger oblong one is for the main burner, the explosive ignition is a different matter and needs to be addressed it can be a few things, your boiler is old but one of the most reliable boilers that Ideal ever made and all parts are still available, a new boiler would be slightly more efficient , but no reason why this can not be easily repaired and maintained

 

[n4nlm]

Hi Ian

Thank you very much for the helpful reply. I fully appreciate the need for the site rules, but I am happy though you can see a way to helping me understand how the system works. The boiler has been incredibly reliable to date and I'd be uncomfortable changing it for the sake of change, so it is good to know that I should not give up on the old girl yet. Also, there is so much more to consider than a simple swap out, do I ditch the sealed system and go for combi, would a combi+store be a better option etc, so I'd like more time to consider this. In all honesty, I should have planned for the eventuality given the boiler is nearly 20 years old. I understand that newer boilers will be more efficient, but I am also conscious of the environmental cost of manufacturing a new boiler. I am currently waiting for some engineers to call in and assess the problem, and I have received an indicative quote to replace the gas valve if that is the fault of £235 (no breakdown of parts and labour). Thank you again for your response, Nicholas.

 

[ianmcd]

I have received an indicative quote to replace the gas valve if that is the fault of £235

You are not getting ripped off at that, remember and mention the Explosive ignition to the engineer changing the gas valve

 

[n4nlm]

Thank you for your help ianmcd. The gas valve was replaced yesterday afternoon for the quoted £235 and the boiler is running smoothly once again, it was tough finding an engineer who had time for such a small job at this time of year. Ignition also quieter and more controlled than before. Hopefully a rekindling of my love for this machine, which has up to now proved to be reasonably reliable, and is kept out of the skip for a bit longer. Thanks again, your kindness and generosity in sharing knowledge on this site is an inspiration to all.