Author Topic: Condesation inside of furnace  (Read 1485 times)

Offline walker

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Condesation inside of furnace
« on: July 05, 2018, 07:37:48 PM »
I have a furnace that is condensating everywhere inside the vestibule while the A/C is running, seems to me moist air for the air door is migrating in through intake pipe for the furnace.

I've seen the opposite happen in a furnace in the winter but never with an the A/C.

The vestibule is completely sealed.

Any ideas on how to prevent this?

Offline Admin

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Re: Condesation inside of furnace
« Reply #1 on: July 05, 2018, 07:48:01 PM »
Interesting.  It must have something to do with this extreme heat.  I wonder if insulating the intake vent would prevent this from happening.

Offline walker

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Re: Condesation inside of furnace
« Reply #2 on: July 05, 2018, 07:50:37 PM »
Interesting.  It must have something to do with this extreme heat.  I wonder if insulating the intake vent would prevent this from happening.

That was going to be my next step.

We took off one of the big plastic plugs in the side of the furnace to see if allowing it to "breathe" would help with the moisture.

Offline Jorgebaloy

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Re: Condesation inside of furnace
« Reply #3 on: July 09, 2018, 11:09:24 AM »
If you have a conventional furnace, the two most likely reasons for dripping water include:

A poorly sized flue pipe
A leaky humidifier

If you have a condensing furnace, it’s likely leaking due to any of the following issues:

A clog or issue in the condensate system
Bad/clogged condensate pump
A leaky humidifier
A bad heat exchanger

Offline walker

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Re: Condesation inside of furnace
« Reply #4 on: July 09, 2018, 11:12:08 AM »
If you have a conventional furnace, the two most likely reasons for dripping water include:

A poorly sized flue pipe
A leaky humidifier

If you have a condensing furnace, it’s likely leaking due to any of the following issues:

A clog or issue in the condensate system
Bad/clogged condensate pump
A leaky humidifier
A bad heat exchanger

Did you even read my post?

None of what you suggested has anything to do with the condensation inside the fucrace when the A/C is running.

Offline DaveP

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Re: Condesation inside of furnace
« Reply #5 on: July 10, 2018, 08:32:38 AM »
Seen this several times, usually a bad seal between the blower compartment and the upper cabinet.  Blower pulls air from upper cabinet, causing warm moist air from outside to be drawn through the intake pipe, condenses in cold pipe.  Just depends on house and basement conditions.
Make sure the gasket is good between the compartments, add a bit more if needed.
I would think insulating pipe could also correct this, keeping the pipe warmer.
Not good for gas valves or door switches especially if pipe is directly above valve.
An external drain T also solves it.


Offline walker

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Re: Condesation inside of furnace
« Reply #6 on: July 10, 2018, 08:46:12 AM »
Seen this several times, usually a bad seal between the blower compartment and the upper cabinet.  Blower pulls air from upper cabinet, causing warm moist air from outside to be drawn through the intake pipe, condenses in cold pipe.  Just depends on house and basement conditions.
Make sure the gasket is good between the compartments, add a bit more if needed.
I would think insulating pipe could also correct this, keeping the pipe warmer.
Not good for gas valves or door switches especially if pipe is directly above valve.
An external drain T also solves it.

I was going to try that bit the configuration of the filter doesn't allow for a drain tee to be put in a good spot.

I'm going to try to insulated the pipe. And also see if they is any spots where the air is being drawn in.