help with a Baso pilot switch that keeps flipping

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Old 01-04-11, 05:59 PM
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help with a Baso pilot switch that keeps flipping

Hi, I am a caretaker in a 12 suite apartment block. The building has an old gas-fired hydronic Weil McLean boiler (maybe 10-20 years old)The gas pilot switch was regularly flipping (about 2 times at least a day) about 3 weeks into our heating season in December, and I would have to go and reset it for the boiler to work. Pilot light was always on. I and plumbers have done the following to handle it over the last 2 years:
1. New circulator pump
2. boiler drained, opened and cleaned out
3. Monitored changes in temperature, water pressure and checked low-water cutoff and have tried raising temp, pressure, lowering temp, pressure, cleaning out low water cutoff valve.
4. Plumber came 3 weeks ago and changed the thermocouple, thermopile, new pilot switch which is a Baso L62AA-5C manual reset switch. He also changed out the outdoor reset thermostat as it was completely dead and set everything up so boiler would operate more efficiently as the pressure was set too high on the system and going to almost 30 lbs.
He also cleaned out the gas burners and checked everything over thoroughly. Worked a good 4 hours on the system cleaning, changing out any worn out parts as above.
5. Boiler worked great for about a week and then the new pilot switch started flipping again!
Only thing I have noticed is it happens when the wind blows hard on the side the chimney is on; cannot find any other point that would be triggering it. My manager of the building says the same thing from what she could tell in previous years when boiler would go down, she has been trying to have this handled for at 3-4 years from what she can remember.

Had the boiler/chimney inspectors come out today and told them about the wind situation seeming to trigger the pilot switch and had them inspect the chimney and surrounding areas. Only thing the guy could find was the mortar joints on our chimney need to be redone and maybe the wind is drafting down and setting off the switch somehow.
As a note the pilot switch flips about 5 minutes after boiler cycle is done and is extremely erratic on when it does it; happened twice on New Year's eve and New Year's day, then fine until yesterday and tripped 4 times including around 2:00 am this morning.
Happened again around 4:00 pm this afternoon but so far fine.
Any ideas or points that have been missed?
Have had literally six plumbers trying to figure this out, 4 with our plumber company and two friends who are plumbers and this is stumping everyone! Any ideas or help would be appreciated!
Myrna
 
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Old 01-04-11, 06:58 PM
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Try adjusting the pilot flame a little higher.
 
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Old 01-04-11, 07:22 PM
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The gas pilot switch was regularly flipping (about 2 times at least a day) about 3 weeks into our heating season in December, and I would have to go and reset it for the boiler to work. Pilot light was always on.
Hi Myrna, no real ideas yet, but wanted to clarify something you wrote above...

You said the pilot switch was flipping... but then you said "Pilot light was always on"

So, I'm a little confused by that?
 
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Old 01-04-11, 07:32 PM
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1. New circulator pump
2. boiler drained, opened and cleaned out
3. Monitored changes in temperature, water pressure and checked low-water cutoff and have tried raising temp, pressure, lowering temp, pressure, cleaning out low water cutoff valve.
While these are all good things and part of a normal maintenance schedule (with the possible exception of the new circulating pump) none of them has anything to do with the pilot flame safety switch tripping.

Mike has given you good advice on cleaning the pilot burner and slightly increasing the size of the pilot flame.


Trooper, it is a pilot safety switch. It uses a standard thermocouple to hold a relay closed and the contacts of that relay are in series with the main gas valve motor. Pretty common in larger sized equipment with standing pilots.
 
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Old 01-04-11, 07:39 PM
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I got that Furd, what I was confused by was that she said the pilot was always on... if the pilot was always on, why would the switch trip?

Reading it again though, it sounds like the switch is tripping WITHOUT the pilot going out.

If the pilot is being blown out by a downdraft, OK, the switch will trip.

That's what I was looking for clarification on...

If the pilot is STILL LIT and the switch trips, then the thermocouple is either defective, or not hot enough ... in which case, Mike's advice to turn up the pilot a bit is good.
 
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Old 01-04-11, 07:45 PM
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As a note the pilot switch flips about 5 minutes after boiler cycle is done and is extremely erratic on when it does it;
Here's my theory:

After the main burner cycle is done, the chimney is HOT and the draft through the chimney is increased. If the pilot is 'marginally' heating the thermocouple, this extra draft might be enough to pull the pilot flame from the thermocouple, allowing it to cool down, tripping the switch.

Again, good advice from Mike, in a lot less words!
 
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Old 01-04-11, 07:54 PM
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Here is a PDF file that might prove helpful... the C434A is no longer sold by Honeywell, the Baso is one replacement for it... same exact principle. There are graphics and stuff in this PDF that will illustrate what the pilot flame should look like.

http://customer.honeywell.com/techli...it/60-2073.pdf
 
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