Electrical terminals on Vaillant control board burned off

rpm773

Hi all
I have a 20yo Vaillant oil furnace. The burner was recently replaced (as of 2 months ago). It's a Beckett..it says "Model AF" on it.

Today the burner wasn't firing. Resetting it did absolutely nothing - not a noise or any action. I called my service company and it turns out the control unit was fried, quite literally. (see pic)

I'm having a new one installed now, but I'm wondering what caused such an end to the board I had on there, and if there are risks for the new one meeting a similar end if this is merely a symptom of another problem.

A couple notes that may or may not be relevant

- When the burner kicks on, it makes a loud noise that I would describe as sounding like a chair pushed on a wooden floor....kind of like a groaning noise. That's new with the current burner
- The lights do dim momentarily. I did not notice that on the old burner
- I had been smelling something akin to fertilizer in the cellar for the last few weeks, of which i've been looking for the source. I'm wondering if what I was smelling was the board cooking

The service guy they sent me seemed like a good enough guy, but wasn't very talkative. Any thoughts would be appreciated!

Thanks!
rpm773

Jamie Hall

Something is drawing 'way too much current -- but not enough to trip a circuit breaker. And yes, it is likely that the new board will fry again, unless you find it. What, exactly, do those fried leads lead to?

rpm773

Jamie, unfortunately I didn't get a good look before the tech had it out. I didn't see if the burned terminals were connected to wires from the electrical box or to the burner - they both come on that side adjacent to each other

Although the largest burned area was the terminal marked "b1" and has "rner" (as in "burner") on the other side of it.

And that's a good point. My breaker didn't flip. I'm wondering if I should be calling the my furnace people about the burner or my electrician...

RJMCTAFO

Do you know if the b1 terminal had a spade connector or a screw which the wire went under and then got tightened like the rest of the control? Have had numerous boards do that because the spade terminal would loosen up over time creating an arc. I usually check them on every tune up and tighten the femal connector by squeezing with a pair of pliers. A little dab of the compound used for oxidation would go a long way on the spade terminal also.

billtwocase

Definitely bad connection on the spade connection as mentioned above. Changed many for that reason

rpm773

RJ, I'm afraid I didn't look at that level of detail. The current hook-up is the screw with the bent wire method, but the guy doing that today wasn't the one who installed the burner a few months ago.

billtwocase

The screw terminals can do this also, but rare

Steamhead

What model Vaillant is that?

EBEBRATT-Ed

Hopefully it was a loose connection and won't happen again but If the lights are dimming you have a problem. Is the boiler on it's own circuit?? It should be.

If the lights continue dimming with the new control installed don't wait until it fails again.

Get someone in there that knows how to troubleshoot weather another service company or an electrician.

I would call the service manager from your service company and start there. This isn't a normal situation. A Beckett AF should not dim the lights.

How many circulators do you have??

BobC

I'd put an amprobe on it to see what the current draw is, the motor might be going south.

Bob

Abracadabra

Do lights dim only when the burner kicks on? Not at other times? dimming/flickering lights could indicate a loose neutral, which will create havoc with electronic controls.

rpm773

Steamhead: It's a Vaillant F70 W45 PP, per the sticker on the unit

Abracadabra and Ed: It's on its own 15amp circuit. I have 200 amp service, upgraded in 2010. The dimming just happens at start-up only.

No circulators. It's a gravity-fed hot water system w/ 3 zones and an indirect water heater.

Bob: The burner was a refurb, put in two months ago. For what that's worth.

I have a call into my electrician to discuss the dimming and why the breaker didn't trip. He's the guy who rewired the house for me 2007 and upgraded the service in 2010. Then I plan to discuss with my oil company once I get some answers.

Thanks for all the feedback!

billtwocase

Refurb burner? Sounds like it does not have a PSC motor. Post some pics of this beauty. Sounds like a motor drawing high amps. Why did they replace the burner? Those had Becketts on them to begin with. Also, you can't put an AF on those, not enough static pressure, that is the "dragging chair noise on start." I think you are getting raked over the coals.

Steamhead

I was just gonna say- AF on Vaillant= soot-up. If I were going to re-burner one of these, I'd use an NX.

Vaillants also had baffles in the vertical passages which get removed a lot, resulting in high stack temperatures and lowered efficiency.

Where are you located?

rpm773

Bill, some more pics below

Steamhead, I'm just west of Philadelphia.

I have some level of soot on the floor near the furnace. I started seeing soot at the end of winter 2014. The pics to follow (taken today) is soot accumulated since my annual service in December 2014. At that time, however, I looked at the combustion chamber with the tech and it was snow white. He took the top off of the unit and it and gave it a good vacuum as it was pretty filthy.

I've asked about the soot accumulation on the floor twice, and have been told "they all do this". However I never had an issue with it for the first 7 winters, so something changed.

The burner was replaced in Jan 2015 because the damper dial on it had broken. Link: http://forum.heatinghelp.com/discussion/153261/replace-the-burner-on-a-20yo-furnace

Edit: I have not swept that soot on the floor since my Dec 2014 cleaning. I plan to do that today to see if it's still accumulating, because as I thought about it more I don't see any more there than I did a few days after the cleaning. So it's possible it's just residual...not sure. Will have to watch.

billtwocase

That would be my answer too Frank, NX. Who removes an AFG to replace it with a used AF?

RJMCTAFO

Riello. Riello. Riello. I have probably 20 of these that run beautiful. Must be thoroughly cleaned very year which means opening the door and vac'ing chamber. Carry a combustion cup on the truck. Where are you located?
That soot is the sign of incompetence.

burnerman_2

You do have a circulator by the way... I saw it in on of the pictures