# Vacuum pressure switch tube filling with water



## Erico (Oct 24, 2016)

I think I found the gasket set. It looks like it comes as one set for everything and you just peel out what you need?)

I suppose I can put it back together temporarily with no silicone and order the gasket.

https://www.repairclinic.com/PartDe...r=GCCA070AX30/P1232402F&ss=a36b1d1437851&mr=1


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## yuri (Nov 29, 2008)

If you don't have a proper gasket it can suck air in there and cause the pressure switch to trip. May also affect the drainage.

I would get the proper gasket PLUS put a bit of red RTV silicone on the gasket when you install it. Helps it stick in place and makes a better seal. I would not try just silicone only.

Let the silicone cure for a couple hours B4 starting it.


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## SeniorSitizen (Sep 10, 2012)

Quote: Erico; Strangely enough, after playing around with it several weeks ago and finding no clogs, it worked for several weeks without incident. Now it's shutting down again with water collecting in same tube.
********************************************

The flue is too cold. If you'll look at the temperature records, several weeks ago when it worked you'll probably find the weather was warmer and now the temperature has once again gotten colder causing the failure.


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## Erico (Oct 24, 2016)

SeniorSitizen said:


> Quote: Erico; Strangely enough, after playing around with it several weeks ago and finding no clogs, it worked for several weeks without incident. Now it's shutting down again with water collecting in same tube.
> ********************************************
> 
> The flue is too cold. If you'll look at the temperature records, several weeks ago when it worked you'll probably find the weather was warmer and now the temperature has once again gotten colder causing the failure.



Hmmmm. You may be on to something. What to do about it??

Thanks!!

I just put it back together and ran the lower problem tube over the inducer motor to avoid a trap. I am ordering a new gasket and will be back at it next time here.


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## yuri (Nov 29, 2008)

I doubt it has anything to do with flue temp as high efficiency furnaces have a plastic exhaust pipe which goes thru a warm area. If it had a intake from outside and it was VERY cold like where I am then yeah the air is denser at very cold temps and could affect the combustion/draft. Not a very common issue and it gets to -40F/-40C where I am and we burn that cold air.

I suspect you got a air leak from that bad gasket and it is affecting the works. If we get a crack in a plastic drain trap for a Lennox it won't drain properly and can air lock. Same with other brands.


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## Erico (Oct 24, 2016)

yuri said:


> I doubt it has anything to do with flue temp as high efficiency furnaces have a plastic exhaust pipe which goes thru a warm area. If it had a intake from outside and it was VERY cold like where I am then yeah the air is denser at very cold temps and could affect the combustion/draft. Not a very common issue and it gets to -40F/-40C where I am and we burn that cold air.
> 
> I suspect you got a air leak from that bad gasket and it is affecting the works. If we get a crack in a plastic drain trap for a Lennox it won't drain properly and can air lock. Same with other brands.


Thanks! Definitely going to replace the gasket. 

Re: the rtv caulk. Is that the red high temp caulk? I think I've picked that stuff up at homer's in the past?


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## beenthere (Oct 11, 2008)

Check to see if the pressure switches have a small pin hole in the port the tube/hose connects too. If so, make sure it is not covered. It helps prevent moisture from building in the switch or hose.

Often, routing the hoses to prevent that gully in it, stops the moisture build up.


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## yuri (Nov 29, 2008)

RTV caulk can be black or red. The auto stuff is high temp and black and HVAC stuff seems to be always red.

Permatex makes it in Canada, not sure if they are American too.

I like to put it on the metal of the furnace too as sometimes it gets pitted or eaten away.


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## Erico (Oct 24, 2016)

yuri said:


> RTV caulk can be black or red. The auto stuff is high temp and black and HVAC stuff seems to be always red.
> 
> Permatex makes it in Canada, not sure if they are American too.
> 
> I like to put it on the metal of the furnace too as sometimes it gets pitted or eaten away.



Will this do? Thanks!

http://www.homedepot.com/p/J-B-Weld...-Sealant-31314/205685476?keyword=043425313140


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## yuri (Nov 29, 2008)

Looks good as it does oven doors and exhaust manifolds.


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## Erico (Oct 24, 2016)

yuri said:


> If you don't have a proper gasket it can suck air in there and cause the pressure switch to trip. May also affect the drainage.
> 
> I would get the proper gasket PLUS put a bit of red RTV silicone on the gasket when you install it. Helps it stick in place and makes a better seal. I would not try just silicone only.
> 
> Let the silicone cure for a couple hours B4 starting it.


Getting ready to install this gasket with RTV silicone.

Do you think I should use silicone on both sides of gasket? 

The gasket has a sticky surface on one side.

The plan is a small bead on the plastic cover, adhere the gasket to cover with sticky side, another small bead on furnace side of gasket , then bolt on.


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## supers05 (May 23, 2015)

Erico said:


> Getting ready to install this gasket with RTV silicone.
> 
> Do you think I should use silicone on both sides of gasket?
> 
> ...


If you have the proper gasket, you need just a dap of silicone if the sticky side doesn't stick. The gasket will seal. 

Cheers!


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## bcmcphearson (28 d ago)

I know this is old but so far this is the only post I have found about this problem. Did any of these solutions resolve the problem. I too have one with a recurring issue at a customers house. Thanks!


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