pressure switch with water in the tube

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Old 11-14-19, 07:25 AM
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pressure switch with water in the tube

I have a goodman gmpn080-4 it is fairly old. I am having a problem with the pressure switch hose getting a few drops of water in it and then will not let the pressure switch engage the furnace. the pressure switch is up hill from the inducer motor. this furnace is 20 years old and is the first time having this problem. I checked the condensate trap and flue and both seem to be open. maybe the inducer motor is getting weak and not sucking the water out of the pressure switch line. does anyone know what the suction pressure should be to the switch. I have a water manometer and could test it. this has happened twice in a month. if I remove the hose to the pressure switch and let the few drops of water run out, it will start right back up and run. thanks

frank
 
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Old 11-14-19, 10:34 AM
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The GMP has a long history with heat exchanger problems. The heat exchanger may be cracked and allowing excess condensation to form. When was the last time this furnace had any preventative maintenance done?
The inducer job isn’t to manage condensate. It’s to induce airflow through the heat exchanger.
You may have a slightly clogged drain.
But first with the known history on those furnaces I’d make sure the heat exchanger was ok. If I were to bet I’d say it’s probably not.
 
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Old 11-14-19, 11:14 AM
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how do you check the heat exchanger?
 
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Old 11-14-19, 11:21 AM
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Visually by pulling the blower assembly or via combustion analysis.
On the GMP units sometimes you can notice a distortion in the burner flame when the blower comes on.
 
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Old 11-14-19, 11:24 AM
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Old 11-15-19, 05:14 AM
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wouldn't a cracked heat exchanger set off the carbon monoxide detector? as I understand it the cracked heat exchanger lets carbon monoxide into the home.
 
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Old 11-15-19, 05:19 AM
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No, not necessarily.
UL listed CO detectors are pretty worthless, if that’s what you have. They will not alarm until CO levels reach a continuous level of 70 PPM. So if you have 69 PPM CO in your home, you’ll be exposed with no alarm.
You’ll want non-UL listed low level alarms.
Even then the heat exchanger isn’t going to start pouring CO out into the home.
 
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Old 11-15-19, 05:31 AM
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very nice informative videos. thanks for the trouble.
 
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