Honeywell L8148 Aquastat Arcing


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Old 10-18-19, 08:23 AM
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Honeywell L8148 Aquastat Arcing

I have a 1 year old L8148 Aquastat on an Oil Boiler that was just replaced last year due to a short (which was assumed due to an active water leak) behind the relay.

The boiler just attempted to turn on for the first time yesterday and tripped the breaker. This morning I isolated the components and found that if I removed the Taco circulator pump, the breaker wouldn't trip and the oil burner would fire and run when I manually manipulated the relay. I assumed that the circulator pump was bad.

Replaced the circulator pump, same results, but this time I noticed a dim flash behind the aquastate control board to the left of where the relay is mounted. I removed the aquastat board and noticed arc burns on the housing behind the board and several traces exposed on the board.

I would just replace the aquastat except this is the 'same' short location that occurred last fall when we fired the boiler for the first time so I'm suspicious.

Curious thing, the boiler ran fine without issue all winter last year on the same aquastat. I would think if there was a common wiring problem it would have shorted immediately?

Any troubleshooting advice would be much appreciated. Thanks.
 
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Old 10-18-19, 11:30 AM
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I've never heard of an aquastat creating a short.
It sounds like something was shorting between the board and the case.
Pictures would help the discussion...... How-to-insert-pictures.
 
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Old 10-18-19, 12:09 PM
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I found the issue, I pulled the wire out of the BX between the aquastat and the circulator and found this a quarter of the way up the run. Sorry for the potato picture but the hot is completely welded to the neutral. Just reran the run with outer insulation on up the BX.

Unfortunately, the short resulted in a loss of the aquastat as I'm not getting voltage to the new pump anymore so I guess I'm in another $200.

So my current working theory is the peephole cover for the burn chamber is gone (was like that when I bought the house) I figure at some point in the past year(s) the BX run got so hot (sits right in front and above the peephole door) that it caused the insulation on the wires inside to melt. So I guess I have to figure out how to make a new peephole door. Any suggestions? I'm thinking about trying to find some high temp insulation (like what the fire chamber target wall is made out of) and cutting it to side to plug the hole for now till I can find a fabricator to make me a new door.

Thanks.
 
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Old 10-18-19, 01:03 PM
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Good you found the problem.

Usually the inspection port cover is just a piece of metal hanging on a screw.
You could use a 3" round electrical blank.

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