That's a shame. My Baxi manual has got diagrams showing the internal wiring. It enabled me to make up my own little panel of neon indicators for diagnostic purposes, and connect them to appropriate places. For example, I can see when there's an external demand but the boiler isn't running because its internal stat is satisfied - or I can see when the overheat stat has tripped and needs resetting.
Had a man in. After putting it through the venting procedure, says it's the control unit. Something like 500 quid for the part alone. Asked him why there was no fault code or fault showing. He didn't know. Also asked him if a new control unit didn't sort it, would I still have to pay for it. The answer was yes.
Given it is getting on for half the cost of a new boiler and this one is about 7 years old, I'm inclined to have a complete new boiler instead.
Thing is the control unit still seems to operate normally in every other way. All the software seems to work as it should. Of course it could be a faulty driver or relay etc rather than the processor side.
I contacted Geoff at CET, but it's not a PCB they've repaired, so he said must be an unusual failure. So they don't have a test rig for it.
Sorry to read that. Makes me appreciate my >40 year old boiler which has had only one replacement flame sensor and that was this year as insurance and one circulating pump after 25 years. All the parts are still available, including the cast iron heat exchanger(at a price) and I managed to buy a new spare gas valve for £30 last year. Maintenance is about once every 5 years, blowing the very little soot off the heat exchanger!
I think I might get a 2nd opinion from an official Veissman installer, who would presumably carry a spare control unit for testing.
Or go for a fixed price repair
This lot charge £240
Or these? >
Bloody cold wind out there tonight. Don't envy you!
+1
I can't speak for Veissman but when our Vaillant boiler went on the blink due to water damaged electrics we got our fingers burnt by using a local man who randomly changed bits without effecting a cure (and charging for them all). A manufacturers fixed price repair deal (about £250 iirc) included every possible part that might be needed other than the case and the heat exchanger, and that's more or less what we ended up getting! Also came with a one year warranty on the repair.
Tim
Right. The one I picked came from a Viessmann list of approved repairers, and were reasonably local. One who could either test the PCB or carries a spare for test purposes would be well worth it.
That would be more like it. Although my gut feeling is it's something pretty simple
I'll try them all tomorrow. Thanks.
I'm ok thanks to a couple of fan heaters and immersion. ;-)
I changed from the old RS BE Potterton just to save on gas costs. And a quick calc says this boiler has done just that - even if I have to replace it. But had I paid labour for the installation, not.
Do you have the option of a manufacturers fixed price fix?
I'm just going through the options. At least some of the fixed price options seem to want you to take out some form of insurance policy too - or that's where any warranty for the repair comes from.
I'm still not convinced it isn't something relatively simple.
The processor part of the board seems to work normally. Which would suggest it is a driver on the PCB which has failed. Or something else. ;-)
Your experience with the official Viessmann installer suggests that installing is about all they do. I can't believe a pukka engineer wouldn't just plug in a new control box to eliminate it from their enquiries. Maybe Viessmann's tech dept would advise you further or suggest such an engineer?
I've asked them. They don't recommend anyone. Just referred me to their list of official repair men.
I've phoned one of those that Stuart gave.
Got voicemail and left a message yesterday afternoon. Not got back to me yet.
This lot claim to have Viessmann diagnostic software (whatever that means). You're a bit outside their range, but not by much
I suppose the other option is to talk to whoever supplies Viessmann bits in your area. They would probably know who fixes, rather than just installs, the boilers. It's how I got my old leBlanc fixed
Problem is, no one does competent level diagnostics and repair on that kind of thing in the field... so a board swap is about the only fix if that is the case.
Two have got back to me. First one I asked if he was familiar with the weather compensated version with additional zone controller. He said not.
Second stated right away he had a 70 quid call out charge regardless if he could fix it or not, after being told the symptoms.
Waiting for the third to get back to me.
Right. But the boiler already has on board diagnostics. But isn't showing a fault code. They seem to just cover north of the river. Here be dragons, etc. ;-)
Yes. That sounds like the way to go.
You don't mind that so much if it is a fix. This engineer is suggesting you pay for it, even if it isn't a fix. Sounds a bit of a clown
Bit of a long shot but some PCBs listed here......
Only appear to list a WB1. Mine is a WB2. I asked Geoff at CET, and he's never had a WB2 one in for repair, suggesting they don't normally give problems.
Must be the wrong time of year to get a repair man. I've contacted some half dozen, and they either don't want to know, or need me to sign a service contract too. Which I'm not going to do.
I'm confident the fault is in the PCB. All the various sensors check out ok. But the lack of any fault code confused me, as the boiler does a self test before firing.
So decided to spend some time on the PCB. I'm reasonably OK at fault finding - but need a schematic to do so. And can't find one anywhere.
So decided to draw one out myself, referring to the PCB.
First thing I noticed was there were a number of PCB mount fuses. Not user replaceable - they are soldered to the PCB. And one had failed. Didn't have the correct replacement, so lashed in a glass type of the same rating.
Boiler now attempted to fire. And then shut down with the error light on, and a fault code. EE. Which isn't mentioned in my service manual. But other E codes refer to the controller.
So went on with my drawing. The ignition module is controlled by an opto isolator. The control side goes to the processor, and the switch side 240v to the ignition module. And there is no 240v to that when the boiler is attempting to fire.
So I've ordered up a new opto isolator (or rather 5, as that's the minimum) and the correct fuse. They should arrive tomorrow. Fingers crossed. ;-)
All over my head, but wish you luck :-)
I'm impressed and good luck. Perhaps the DIY wiki should include circuit diagrams like yours?
Sadly, I only got as far as doing a very small part drawing. Which of course helped me find the faults.
I do wish makers of these very expensive devices would make such schematics available. I really can't see they are 'commercially sensitive' or whatever. The demand for a pirate version of the board would be tiny.
What I couldn't understand was the many fuses scattered across the board. Very worthwhile if they offered an exchange board. But a pointless expense if they only do new ones. It's something you do to make it more repairable.
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