HVAC closet as Plenum/Asbestos Pipe Covering?

This is a 1969 apartment complex turned condo. This closet is being used as an HVAC plenum. My concern is the water pipe insulation. Possible asbestos? Also concerned about wall/ceiling/floor penetrations pulling air into this system and distributing throughtout this 1,200 sq. ft. 3 bathroom, 2 bath condo. This is the only return for the entire apartment. I’ll try and get a better picture.

How is it being used as a plenum?

It’s tucked so far back into the furnace room why would this be a concern?

Are they not sealed?

1 Like

It isn’t. It’s a closet. The open air filter door to the furnace plenum likely threw the OP off.

Robert. The water line is for the water cooled HVAC condenser.
Condensate dispersal lines require air gap/clean out and water trap were the two condensate line merge.

Is the concern that because all of the return air is being pulled through the louvered door and into the closet area, that there is a potential for asbestos contamination of that air?

If we don’t have asbestos training in the curriculums I really think we need to add it.

Yes. Air is going to be pulled from this entire area, not just through the louvre door.

There is no return supply duct serving as a plenum. Therefore, air s being supplied not just through the door, but the entire surrounding environment.

I think it’s a valid concern. I wouldn’t want that situation in my house. I wouldn’t throw out a major red flag on it, but maybe note it as something that should be evaluated further, especially if it is asbestos and is deteriorating.

They should Martin. There is a lot of misinformation about Asbestos. I suggest anyone interested in learning more look up the Free online courses offered by OSHA. If you want the completion certificate there is a small fee I believe.

1 Like

If this is true are there any concerns about sewer gas (floor drain)being installed in a HVAC Plenum? I believe the return plenum ends where the filter begins. Just my two cents.

There are many furnace like this installed in my area that are gas fuel. Do we now have gas piping installed in a Plenum?

1 Like

The return sucking air from the same tiny closet as gas-fired furnace? I though we had rules for that :thinking:

Same rule as installing a floor drain in a plenum :joy:

It’s a First Co. 10CW 120 Electric.

An enclosed portion of the building structure, other than an occupiable space being conditioned, that is designed to allow air movement, and thereby serve as part of an air distribution system.

IMC 602.1 General
Fuel-fired appliances shall not be installed within a plenum.

If the OP was a gas-fired furnace, a return duct work would have to be in place to supply return air from outside of the closet. This the way it’s done in my area in condos/apts with limited space.

So as I asked before, floor drains may be installed in a plenum?

While not ideal, I’m not aware of a rule against that. The answer is it depends on the specific installation. The trap would have to be kept primed and protected. If there is too much negative pressure, the trap would have to be relocated.

Do you have a rule that says otherwise? (other than Mr Martin’s Rule :slight_smile: )

Nope just asking the question :wink:

It may be those pipes terminate to another location.

Robert… I would simply note possible ACM… and move on… let the buyer decide what to do about it. In general, if asbestos material is not cut and or disturbed, it’s not a concern.


Just to clarify, I do not mean that the design of the system is using the closet as a plenum. However, because the return is not directly connected to duct that is drawing air from outside the closet, the end result is that the closet has become a dominant area where air is going to be drawn from. Any openings in the penetrations, floor drains, etc., will supply air to the return.