# Vent Cap For Condensing Furnace Exhaust.



## slowsol (Aug 27, 2005)

This is my neighbors house. 









We just realized that my daughters (1 and 3) have a favorite game of picking up those rocks on the ground and throwing them down that PVC vent. 

We stopped it, but I was wondering if I could put some type of vented cap on there to make sure it doesn't happen anymore. Will the cap restrict airflow and cause any potential damage to their furnace?


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## CarpenterSFO (Dec 12, 2012)

Normally the exhaust has an elbow downward, like the intake, with a large mesh screen over both.

Edit: Manufacturer's instructions usually specify some separation between the intake and exhaust.


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## beenthere (Mar 5, 2009)

CarpenterSFO said:


> Normally the exhaust has an elbow downward, like the intake, with a large mesh screen over both.
> 
> Edit: Manufacturer's instructions usually specify some separation between the intake and exhaust.


The exhaust is not suppose to point down.

Screens over the exhaust tend to build up frost/ice in the winter, and cause the furnace to lock out. And the house to have no heat.


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## CarpenterSFO (Dec 12, 2012)

beenthere said:


> The exhaust is not suppose to point down.
> 
> Screens over the exhaust tend to build up frost/ice in the winter, and cause the furnace to lock out. And the house to have no heat.


We've installed a couple of direct vent furnaces where the manufacturer's instructions said to point the exhaust down. I didn't install them, but I did read the instructions and watch what the HVAC guy did. Might have been an exception, and of course frost and ice aren't a problem around here at all.


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## beenthere (Mar 5, 2009)

On a direct vent system. pointing the exhaust down, cause the intake to bring the combusted gas back in. And of course reduces combustion efficiency.

What brand furnace were they.


PS: Even in a desert, water/moisture is a byproduct of a condensing furnace.


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## CarpenterSFO (Dec 12, 2012)

beenthere said:


> On a direct vent system. pointing the exhaust down, cause the intake to bring the combusted gas back in. And of course reduces combustion efficiency.
> 
> What brand furnace were they.
> 
> ...


Thanks, beenthere, I stand corrected.

To correct my prior post - it appears that straight or with a tee installed vertically at the end, are typical, not with a 90 elbow down.

Now I'm going to have to drive around and check a couple of our installations. Hopefully I'm just remembering tankless water heater installs, and not furnace installs.


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## superseal (Feb 4, 2009)

Screen mesh will corrode in short order unless it's the stainless variety...and can cause icing issues as previously mentioned.


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## flashheatingand (May 3, 2008)

They do make a cap for condensing furnaces. I call it a ding-a-ling top, but not sure the technical term. It looks like a mushroom.


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