Ideal Mini C28 Boiler not igniting!!!

[Agile]

Ginja, you seem to think that a repaired PCB for £70 is good value compared with £85 for a brand new one.

Your plumber may well be correct in saying the GV is failed and blew the PCB.

However, that makes me suspicions that fuse values are not correct! Whats the fuse value in the fused spur supplying the boiler? Whats the fuse value on the control PCB ?

Can you post a photo of the UNDERSIDE of your PCB with the burnt track so that I can hopefully confirm its likely to be a failed gas valve?

We would replace the GV and PCB for about £325 ! I suspect your fellow is giving a high figure because he wants the job of fitting a new boiler.

If you installed your own boiler then you would be risking illegal gas work as well as potential problems with the warrantee and notifying Building Control as fitting flued gas appliances are a controlled activity.

Tony

 

[ginja]

Hi Agile, thanks for your reply. I'm not in a position to install my own boiler, I'm just a bit of a pauper at the moment and trying to work out what is and isn't worthwhile doing. I agree, having checked the terms and conditions on the adlink site, it isn't worth getting one of their boards rather than paying for a new one. Regarding gas pipes, yes, I am absolutely not going to touch it and it is definitely be left to the professionals. However, I am happy soldering copper joints and doing most regular plumbing tasks around the house, so I'm just trying to work out what is and isn't possible. I thought that I could install a boiler myself when replacing like-for-like, and providing I could find a qualified plumber happy to do it, have them do the gas pipe work and comission the boiler. However, like I said, at the moment this isn't an option - any work needed to be done will be undertaken by a professional. I just need to know I'm not getting ripped off, or that they are up-selling, when all it possibly needs is a new PCB plugged in.

I've just taken some photos and marked them up, see below. Having your opinion on this would be really valuable. Incidently, the fuse on the board isn't blown, and none of the others seem to be either.

Going from left to right, the connectors along the top plug into power PCB, the centre one goes to the flue fan and flue sensor, and the one on the right is the connector for the gas valve.

Hillsey, can you remember if your board looked like this?

In this picture the gas valve plug is on the left, flue fan connector is centre above the burnt bit, power PCB connector on the right.

Close up

 

[ginja]

I've checked all the fuses on the boiler. The fused spur supplying the boiler has a 3A fuse. The fuse on the power PCB has T1.6AL240V on it. The fuse on the control board (the one that has burnt) has F4AL250V. None of these has been messed around with since installation as far as I'm aware.

 

[matt1e]

That board has problems in all the usual places,but be aware that although the relay with the burnt out track is the usual one that burns away at that pin its usual to find it burnt out just around the pin not the whole track,that damage may have been caused by an overload but its more than likely going to be a problem with the fan rather than the gas valve IMO.
the fuse on the ignition board should be a 3.15A not a 4A(now I wonder why its been "upped").
If that board is going to be repaired then all the carbon deposits would have to be removed
As tony has said it would have been far better value to pay an extra £15 for a brand new board

Matt

 

[ginja]

Thanks for you reply matt1e. As I was marking up the pictures I came to the conclusion that it may be the flue fan, following the PCB traces it wasn't in the right place for the gas valve. The flue fan has been a bit temperamental during the winter - after running hot water for a while and then turning off, the boiler often wouldn't re-ignite when there was a new demand for DHW. But it wasn't in an overheat situation, and could be got going again by turning on the central heating. This makes me think it's a problem with the board rather than the fan, which rotates freely. I think I'm going to try replacing the board before anything else, though I'm going to be in massive trouble with the missus if it doesn't work, let alone £100 out of pocket!

 

[Agile]

All the fuse values you have quoted are correct.

Including the 4A fuse used on the Honeywell PCB.

Those resistors designated as "heat effected" ( sic ) are normal and always show signs of discolouration.

The pin beside the burnt tracks is one of the connections to the APS. I would be visually examining the wire to the APS for any signs of damage.

The actual damaged track is non conclusive as not all of the tracks wired in series are damaged.

I would therefore conclude at this stage that the damage has been caused by arcing rather than overload.

My full conclusion is that the failure mechanism was an initial arcing at a faulty soldered connection to RL2 which was followed by further arcing once the plasma was established to other points in the vincinity.

My solution would be to replace the PCB but initially to operate it with a 1/2A quick blow fuse in the control PCB just in case.

Around 2002/2003 there were some problems with fans and whilst they rarely caused overcurrents I might power the fan externally and measure the current taken but thats more as a precaution than relevant tot the current problem.

Tony

 

[ginja]

Huge thanks for your analysis, agile. I'm going to order a new board tomorrow morning, and get a low amp fuse for testing. When you suggest 1/2A fuse, do you mean 0.5A or did you mean 1A or 2A? Hopefully I will be able to sort it out for Tuesday... I'm beginning to smell of chlorine from going to the local swimming pool for my showers!

 

[ginja]

I received a new Biasi Full Sequence PCB today, plugged it in a bit tentatively with a 0.5A fuse, and once I'd realised that the plumber had turned off the gas at the tap, the boiler fired up and it's running like a dream. Swapped the 3.15A fuse back into it, and everything seems fine after a couple of hours.

Many thanks for all your advice. I just need to change the pressure vessel sometime over the summer and she'll be good for another few years.