High Efficiency Installation Question

[inspectorwill]

Have to admit I am confused by this particular installation. It is a York high efficiency unit installed in an interior closet with no combustion air openings. The unit is equipped with an ABS vent pipe that splits as it exits the top of the cabinet. The burners are located at the top of the unit but the confusing part is a second port atop the burners that is open to the closet interior. I can hear and feel air drawn into the port atop the burners when the unit is operated. However, with the door closed, this would diminish the amount of air through the port if necessary for combustion. Additionally, the ABS vent connection at the top of the unit feels loose and when I hold my mirror up to it, condensation immediately develops. This is not the typical installation I see with high efficiency furnaces. See attached pics. Thanks.

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[Jim Katen]

Annular opening between pipes?

[inspectorwill]

This was a multilevel condo with no access to the roof where the vent pipe and a/c condenser were located. Still attempting to gain access through HOA. Until then I can't answer, sorry.

[plummen]

Looks like a hack job to me.

Im guessing they couldnt make room for proper size flue pipe so they used two smaller pipes to compensate.

The furnace running without combustion air pipe is more common than you might believe,usually for space issues as well.

It cuts down on the efficiency of furnace because youre using air you allready heated for combustion,not as dense as fresh cold air.

Definately needs to atleast have louvers installed in door,whats the sq footage of the rooms supplying combustion air if louvers are installed?

[hausdok]

Hi,

The York units can be installed either way with air from outside or air from inside. As plummen has said and you've already noted, it needs combustion air openings. Keep in mind that it may not draw air from a bath or bedroom and that the openings must be properly positioned and sized for the BTU input of the appliance.

Can honestly say I've never seen anyone use black ABS for exhuast vent material on a category IV appliance; around here they seem to prefer the PVC.

I could see them using a two pipe system - one for intake and one for exhaust with a combi vent on the outside wall but they'd have to use a coupler on the inside similar to the combi vent that brings oxygen into the appliance from outside and they'd have to cap the combustion air opening on top of the burner chamber. I don't think I've ever seen that done here.

ONE TEAM - ONE FIGHT!!!

Mike