Halstead Best 40 will not ignite - damaged inition pcb.

[jimox]

Hi - my Halstead stopped working on xmas day.All thermostats,programmer and zone valves are fine.
Pump comes on but fan will not start - so no ignition.
I went through the fault finding chart and it says I should get :- at terminal 1, a pink lead on the Ignition unit "10v(good) / 1v(bad - so change either the Aquastat, Thermistor or the Potentiometer)" I get less than 1v dc.
At the same time I discovered a leak from the 28mm plug at the rear of the boiler though this seemed to be just dripping into the back of the boiler casing and not onto any electrics.
I contacted Halsteads tech support who said I could simply buy a new plug to fix the drip but to check for 240v at terminal 5 - I got nothing. I did tell them there was 240v at terminal 10 which they said was a good sign, but (worryingly) they said they "do not know what the pink lead at terminal 1 is".
Anyway after a bit of digging in forums it seems the fault may well be the ignition board - a few people have described how they can be inspected and repaired - seems a faulty relay/dry joints can cause the fan to fail.
Opened mine up to discovered a large amount of burn damage on the pcb in the centre of the board under/around what I presume is the fan relay so I guess a replacement is due.
But before I shell out over £100 on a new Ignition board does anyone know if its possible for the Aquastat etc to have caused the damage to the pcb as I don't want to screw up another pcb - obviously I will drain down and replace both 28mm plugs first.
Thanks in advance for all replies.

 

[Slugbabydotcom]

The fan or the wiring to it is a possible cause if not just dry joints.
Sorry I can't say any more than that as really you need an RGI to sort it out for you. We can not offer any advice that would involve any work within the combustion chamber.

 

[jimox]

Thanks for the prompt reply, I had already checked the fan motor, its free and I'm getting 50 ohms resistance.
Also none of the parts the Halstead manual suggests replacing or the ignition pcb are in the in the combustion chamber - I was just asking for a advice on whether this relay can get damaged by any other part becoming faulty.

 

[Agile]

Yes, but you should not have been access or touching the fan!

 

[jimox]

Please explain why.

 

[Dan Robinson]

Did you read the forum rules when you signed up?

 

[Dan Robinson]

Or maybe even the dirty great announcement at the top of the forum listing on DIY Gas work?

 

[Slugbabydotcom]

Seeing as you seem to be fairly capable in the electrics department.

50ohms and a free spinning fan is good I would have had a new board in right there unless my sixth sense told me there was something else amiss [but I can afford to learn another expensive lesson]

Anyway I'm staying with you a bit on this due to your cautious nature.

The fan wiring is a very rare thing to cause a problem but if you can identify the wires from where they plug in to ignition board you could check these to earth.
Again low on the suspect list, the gas valve coils also could also do with checking. Can't remember exactly but you might find 1.6k on one coil and double that on the other. Of the 5 pins the middle is an earth and the top and bottom two are pairs
The only other thing that the ignition board sends a live out to is the air pressure switch. Again check these wires to earth.

When I see something burnt out on a board I try to trace back to see what component the burnt out part feeds then scrutinise that item and wires feeding it. Usually fan, gas valve or in the case of a combi, the pump.

All the above can be done without taking the combustion chamber cover off. Please keep out of there! The insulation board usually falls off when you enter the burner area and the ignition wires melt against the casing if not carefully placed. That's just a snippet of the problems you could have if you're not experienced and qualified. We would be working against the interests of gas safety if we told people what to do inside the combustion chamber or any part of what is referred to as the 'gas train'.

 

[jimox]

Thanks Dan - to be honest I didn't read the small print but have now.I wouldn't have thought swapping out a pcb etc would not be allowed and so I think its best if I get my local Gas safe/Corgi heating engineer in to advise and fit/commission it etc and I will stick to the zone valves, programmer and thermostats (if that's not breaking the law) - daft thing though, all these have 240v ac on them and its not illegal to frig around with 'em, presumably because if I cock something up its me who gets zapped and not half the street blown up.

 

[jimox]

Thanks very much slug...com, may have a look again tomorrow but following Dans reply and your advice and the wife pushing me to "sort this bloody boiler out" I'm reluctant to proceed.

By the way I had a local plumber/heating guy in on the day after I had noticed the 1volt dc problem on the Ignition unit and at first he wasn't sure what was going on and tried in vain to remove the fan motor as per the Halstead instructions - he said this was to "check the Venturis".
I know he removed the front burner panel to try to get room to drop the motor but couldn't do it so he may have disturbed any leads behind this.

Looks like I'm going to go for a new boiler - Worcester B or Vaillant this time and get an half decent installer in.

Many thanks again for your advice.

 

[Agile]

Your boiler can be repaired but would need a rather persistent engineer who will stay to the end. Most will just want to replace it for you!

Its not very efficient and a new boiler will save about 20% of the gas.

There are better boilers than the Worcesters!

Tony