Biasi Combi boiler will not ignite

[GordonNo2]

Got a Biasi combi boiler "M90e.28s" which will not ignite. Problem is the same whether switching on for hot water or central heating. The fan turns accelerating, there are quite a few clicks going on sounds like contact opening/closing..... there is no ignition i.e. no flames, then the fan power falls off... few more clicks then the whole sequence starts again. Lots is fan whirring and switch clicking but no flames. This persists as long as I have a hot water tap on or I am asking for the central heating to come on.

Called out a service engineer last night. He took the white front cover off and then very violently removed the steel looking cover around the gas boiler unit with the little window in it, bending it around the edges! He then started mucking about with the pressure switch by blowing down the clear hose to the switch whilst turning on the hot water tap at the kitchen sink (the tap can be reached whilst standing in front of the boiler). The boiler did the usual fan whirring and clicking thing but no flame!

He then declared that the air pressure switch was faulty and he couldn't get new one till the morning. He said he would go to a local shop to get it, I said I could do that (being and trained electronic technician) and could replace it, if that was all it required. He said OK and gave me all the details of the stockist.

I'll get the part tomorrow but was wondering, if I replace the air pressure switch (APS) all electrical power of of course, and turn on the hot water tap will the boiler unit fire up without the steel cover being back in position? Or do I need to fit the new APS and replace the cover before I can test it has worked. The "service guy" did all his testing with the cover off but I do not know if he was waiting for flames or was just checking other things. He didn't say.

Any feedback would be appreciated

 

[GordonNo2]

Also forgot to say once I removed the switch I tested it for continuity when blowing down the clear tube attached to the switch. The switch does switch and the contacts open an close as expected. Hence I am a little worried the switch itself is ok! Assistant in the spares shop did say they are very sensitive devices and he needed serial number and CF no to get the correctly set up replacement switch (which I should get tomorrow). I thought I had best just go a head and replace it and at least take the fault finding one stage further.

 

[Foobix]

If the fan is cycling on and off without the boiler firing up then it is possible that there is a faulty relay switch on the pcb.

 

[zk]

most likely to be the ignition board, provided the fan venturi and the aps have been checked, you will need a RGI to do these checks.

 

[GordonNo2]

Many thanks guys for the feedback. I should have the new APS sometime today, I'll fit it and see how it goes. If it doesn't fire up then I will call in a RGI as recommended.

 

[Agile]

From your description of what he did, it sounds as if that is not the fault anyway. It does not sound as if he is very competent.

As ZK says its most likely to be the ignition cct.

Only gas registered people are meant to open the combustion chamber and when refitting its essential both sides are INSIDE the lugs on the chassis.

Also the ignition and flame detection connectors just above the PCB box must be the same colours either side of the connector.

 

[GordonNo2]

Got part fitted it and no change still not igniting. Called Biasi for recommendation of local RGI. Called in recommended engineer and explained the saga thus far. Within 10 mins he followed trail to ignition PCB and tried out new replacement PCB which he had available, boiler fired up first time!

Lessons learnt, get a RGI recommended from the manufacturer of the appliance, they carry the parts and the manuf has obviously good knowledge of his credentials.

This guy was very good even took the kitchen cupboard apart so he could get the side panels of the boiler as he said this is the only way to disassemble / reassemble the unit. He said other guy should not have ripped out the cover he could have damaged the boiler permanently or left me with an extremely dangerous gas appliance.

Many thanks for all the feedback, it helped me greatly with the decision making process especially not to throw good money after bad.