Pressure switch problem


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Old 01-10-12, 03:39 PM
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Pressure switch problem

I have an Airco/Olsen oil furnace, BCL100B2U, with a Honeywell pressure switch, I think model # is 1039D5/B.
About a month ago when calling for heat, I can hear burner start pre-purge, a little while later I can see a flame in burner. At this point the pressure switch will click rapidly eventually causing the flame to go out. Burner attempts to come on again with same results ending in lock out mode.

First service call: Tech jumped the switch and everything worked. When he removed the jump, it also worked. Not sure why it started working.

After about 2 weeks, same thing happened again.

Second service call: Tech measured negative and positive pressure. Both were normal. Checked direct vent and everything was clean. Replaced switch. It worked fine for about 4 hours then it started clicking again.

Anyone have some ideas as to what may be causing the issue?

Thank you.
 
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Old 01-10-12, 04:05 PM
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When the pressue switch fails to close, the problem is a bad pressure switch about 2% of the time.

98% of the time there is a problem or defect in the venting system that the pressure switch is testing.

Your first service call was done incompetently. Measuring the pressure being measured is the proper way to check on the system.

The second tech did measure the pressure. Do you know the pressures obtained?

It's always possible that the new pressure switch is no good. If so, it should be replaced under warrentee by your service agency.

The alternative is that the tech measured the pressure, but didn't do so correctly or misinterpreted the result and replaced the pressure switch when the problem lies in the venting system of the furnace.

I'd talk turkey to the service agency and insist they send their best guy to correctly diagnose the problem. If the new pressure switch is no good, that's forgivable if they replace it on their own nickel.

If the new pressure switch isn't the problem, then they misdiagnosed the problem twice and should correct the problem and issue you whatever refunds you might be owed for not doing the job properly the first time.
 
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Old 01-10-12, 05:19 PM
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Thanks for your reply. I don't know what the pressures measurements were but I will call them tomorrow and try to find out.
I tried both the negative and positive pressure valves on the switch and I do hear a click. I also blew into both black and white tubing and everything was clear. With the switch jumped and the furnace on, I connected each tubing one at a time. When both are connected, I hear a click. As soon as I remove one, I hear another click. So it sounds like the switch is properly working?
 
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Old 01-10-12, 09:06 PM
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Blowing into pressure switches is not recommended --- that can damage their calibration.

You need to do what the second repairman supposedly did, measure the pressure and see if it is correct. if it is and the pressure switch doesn't close, the pressure switch is bad.
 
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Old 01-12-12, 09:21 AM
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This may be a stupid question but I noticed part of the negative pressure tube lying on the round cylinder part of the Beckett burner that goes into the furnace. This round cylinder gets hot during operation. Could the cold air flowing though the tube hitting the warm part cause issues with the pressure switch? Could it create condensation or mess with the pressure?
I've noticed that when the switch does fail it has always been at night and on colder days.

They are coming back today to replace the switch. Hope it resolves the issue.
 
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Old 01-12-12, 10:49 AM
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Ummm. I didn't notice you have an oil furnace. My comments would not apply to an oil furnace.


Sorry for this mistake --- I was really being dumb I'm afraid.
 
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Old 01-12-12, 07:06 PM
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Do you have outside air coming into the burner?
Did you ever solve your limit problem?

Here is the installation & operation manual for your furnace:
http://www.ecrinternational.com/secu...ument/2519.pdf
 
 

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