Replacing Vitodens 100 PCB on my own

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I have a Viessmann Vitodens 100 WB1B without the combi plus. Currently it is throwing an FF error. This happens after 3 tries on its own to start up. It gets through the first few steps, I hear what sounds like an ignition (like when you turn your gas stove on) but it does not hit the step where ignition is detected (a flame icon). I have to reset it about 20-100 times before it works, so eventually it does work, but only for a while. The worst part is, my system won't turn on the AC unless it knows what the boiler is doing (or something, who knows) and why shouldn't it be the hottest part of the year when this happens.

I've had two servicemen come so far and say it's the PCB. So I will trust them, even though I don't really trust them, because it seems odd to me that the controller can work sometimes (my hunch is something is clogged, but I don't know anything about boilers). I also don't trust them that much because they want to charge $1600 (Canadian) which is probably an upsell of the part by 3 or 4x. I would love to have them install it because I trust that part of their skill set, but I know when I am being fleeced.

So. I just ordered the PCB off ebay (https://www.ebay.ca/itm/184350816460). It's used, maybe it works, I don't know. But I feel like I should take my chances rather than give up most of a paycheque to fix this boiler ("top of the line" my ass, I hate this thing, nothing but problems, and $1600 is almost a new boiler entirely). I did repair PCBs from robots and other embedded devices for 2.5 years of my life, soldering CPUs, caps, resistors, you name it. So I trust myself to handle the board.

What I am looking for is any "you will get yourself killed" warnings. I am not touching any gas components (other than the instructions telling me to turn off the gas supply while installing the control unit) or any mechanical components or any lines or valves and it seems like the only setup I have to do is

- Match the board and boiler
- Choose the gas type (I am on propane not natural gas)
- Set elevation (well, double check it's not set incorrectly, who knows what settings the board comes with)

Anyway, any advice is appreciated.
 
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Add to your list "I am in Canada".

This is a UK site, our replies will be tempered with our legal restrictions.

IMO I'd go for it, if you can get the instructions for changing it from the manufacturer then that should tell you all you need to know.
I'd be looking at the original board for dry joints etc. first.
 
Yeah I would actually prefer to see a resistor split in half or a bad joint and just repair it with some solder or use the incoming board to replace a component. I'm also wondering if a RF shield would help as I read this is also a potential interference issue.
 
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RF shielding can't make it any worse but it needs to be working before thinking about that.
 

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