Ideal Classic Fault - Any Suggestions

[Foodface]

Got called out to look at a boiler that is cutting out intermittently, the boiler always comes on in the morning and is usually set for 18 c in daytime. The problem usually occurs when the customer is calling for more heat at nighttime as they turn it up to 21 c but then the boiler cuts out and does not come back in for hours. Initially I was thinking faulty stat or something along those lines, but when I inspected the boiler I noticed two things.

1. The fans propellers are missing
2. When the boiler is cut of it won't try to go through the inanition process even after reset, but when you tap the control box that houses the gas valve it kicks in, fan runs and hey presto the boiler fires up.

The fan appears to be working OK apart from the missing blades and it has continuity through it, but am torn between a fault on the gas valve or fan fault as maybe the lack of propeller blades is causing it not to run adequately.

Since leaving the job the boiler worked fine for 3 days then started to cut out again but again worked when the control box was tapped.

What does everyone else think.

Thanks

Foodface.

Read more: http://www.ukplumbersforums.co.uk/central-heating-forum/44419-ideal-classic-fault.html#ixzz2EgPS1wOP

 

[lame plumber]

looks like you've answered your own question! tap tap tap and it works!

 

[R1CKY]

Sounds like a sticky relay on the PCB.

They sometimes have problems with the pilot solenoid on the gas valve, but you'd hear it trying to spark if it was that. Lack of fan blades won't make a difference, they often go brittle and snap off or someone has removed it when trying to release a seized fan (another common fault).

I'd go for the PCB myself.

 

[Nostrum]

The boiler should still try and fire with a faulty gas valve, so I would rule that out. Sounds like a board fault but the fault finding chart in the servicing instructions it quite comprehensive if I remember, APS needs checking for continuity and I would also check for loose/bad connections in the control box.

 

[Nostrum]

and i'm too slow

 

[Billy Bob Bob]

pcb failing

 

[mfgs]

I had a similar problem a few months back. Boiler would just randomly decide not to fire, no pattern to it. You give the bottom a tap where the pcb is and it starts to run. Replaced the PCB and it has been fine ever since.

 

[vern]

PCB relays known to stick when hot

 

[GrahamM]

As mentioned.
Fans are prone to seizing up and causing issues. Usually a strip down and bit of oil into the bearing will give a bit more life.
Also intermittent faults on boards where a bang on it brings to life is also common. Make sure electrode is firmly connected first and if still giving probs a new board is usually the answer.

 

[Foodface]

Thanks for the help on this one, good job I didn't go gas valve route. Going to pursue the PCB route now, will let you all know how it goes.

 

[arran197]

I'd go PCB too. Like has been said, tapping the control box might just cause the relay to flick over. You can usually see them on the older boards, darkening on one of the relays.

 

[Foodface]

Right I changed the PCB on this unit in the morning today, boiler fired up and left it running. Customer said that the boiler ran for a while, but then the 3amp fuse blew in the spur box. He changed the fuse and again the same thing happened.

Any suggestions.

 

[Foodface]

Just been back, isolated all electrical componants as instructed by ideal. Put back together one by one, fired up and ran fine for the hour I was there. Bloody weird one.

 

[arran197]

Strange. Fan or gas valve, but could be something unrelated to the boiler itself, such as the 3 port of pump. First thing I'd do is check to make sure the wiring to the boiler was correct and not crossed.

 

[JJ The Plumber]

Check the pump.
I've had similar with old pump leaking internally as it warmed up and caused the fuse to blow.

 

[Foodface]

Yeah I went back the day it tripped and isolated every component internal to the boiler and also checked all the external components such as pump, clock/programmer and motorised valve.

Everything was fine, no leaks onto electrics, the board had been installed correctly. Fired it and no problems since, I will be charging the customer for my time though.

Thank you for the help too on this one.

 

[Backboiler]

Am I right in thinking It wasn't blowing fuses until you changed the board? If I'm right, you seem to have created a new issue. With respect I'd be looking at the board installation that you did for errors

 

[Foodface]

I have all ready done that and the board was installed correctly, the issue no longer occurs and the boiler has been running OK for weeks now. I also consulted an electrician and all is good.

 

[JJ The Plumber]

Glad you got it sorted mate