Air Conditioning Vent in Hallway

[Nick1994]

Well it's not exactly a vent for air conditioning but I think it's an "up-duct" for when the house used to have an evaporative cooler. This is my grandmother's house and it was built in 1949. This is at the end of the hallway in a closet where there used to be a furnace in the hallway closet, now the furnace is built into the big A/C unit outside. The filtered air going into the unit is at the ground level in 2 - 8"x14" filtered vents and 1 8"x30" filtered vent. The air conditioning vents run through the attic and vent into bedrooms etc.

This "up-duct" for when the house used to have an evaporative cooler is still in place and my grandparents had no idea it was even there. The closet doors are slatted so air can go trough them. With the A/C running I put a Kleenex up to this up-duct vent and it sucks it up to it. I have it blocked off now so that she isn't air conditioning the attic when the unit is running and also so the heat doesn't come back in through the attic into the house.

I just want to make sure I'm not hurting anything so if someone has HVAC experience please chime in. Thanks.

 

[Pop_Rivit]

As long as it's not hooked into the return air system you're fine. With that much air flow I'd get up into the attic and make absolutely certain before I blocked it off.

 

[EA82]

Sounds like you are sucking attic air in the return from what you are saying, I would call a professional to take a look at it.

 

[Nick1994]

Ok I just looked through the vent and took a picture, I can see into the attic and see the insulation.

What sucks is the entrance to the attic, is almost impossible to get into there. It's at the end of the house at the slope of the roof and some old ductwork to an old evaporative cooler is in the way and you have to be very agile and skinny to slide through.

 

[Donald]

You need an old local HVAC guy.

 

[Kuato]

Since it's pulling air with the AC on, that tells me there is an open return in theattic which will need to be closed off. Efficiency will be increased dramatically by closing off those two "leaks".

 

[sleddriver]

Quote:
With the A/C running I put a Kleenex up to this up-duct vent and it sucks it up to it.

That means their house has positive pressure, which is good.

The quickest way to seal this up is to use blue or pink foamboard in either 1/2", 5/8 or 3/4" thickness. From your photo, looks like 3/4" would fill it in flush. Cut a piece to fit nice & tight, then fill the cracks & any voids with white acrylic, latex, siliconized caulk.

Cheers to you for finding this! It'll save your grandmother some $$$ on her heating/cooling bill from now on.

 

[JimPghPA]

If you reduce the return path too much you could increase the temperature that the heatexchanger runs at when the furnace is in the heating mode. That can shorten the life of the heatexchanger by several years. Something that you probably would not see the results of in a year or so, but several years later the heatexchanger will fail (if you do not have enough return air).

 

[Rand]

where does the outdoor system get its air from?

 

[Nick1994]

Originally Posted By: Rand
where does the outdoor system get its air from?
It has 2 "vents" that are filtered and are 8"x14" and one that is filtered and is 8"x30". It is at the end of the hall at almost ground level and the 2 smaller suction vents are in the bedrooms and the big one is at the end of the hallway