New A/C works great but house smells like old brick/masonry when it runs!

JimHP

We had A/C installed recently. It works great, but when the AC runs we get a noticeable smell of brick/masonry. Two of the runs go under uninsulated build-outs on the rear of the house. Both needed to have holes cut through three layers of brick for the ducts and venting. Is this the reason for the smell? If so, what can be done to alleviate it? If not, any ideas what is generating it?
Thanks.

STEVEusaPA

Smells like you might have some return duct leakage.

mattmia2

Is it all ducted or is some of it joist or stud bays that have been panned?

I have had some flow through humidifier pads do this, smell like masonry when wet but this isn't your problem.

Also make sure the condensate is draining properly and look inside the furnace or air handler to make sure condensate isn't leaking in to it.

HVACNUT

If there's a lot of brick dust and debris lying around and there's a leaky return nearby, its sucking it right in. Take care of it before it clogs the evaporator and builds up on the fan blades. Is the air filter at the air handler? 

ChrisJ

When I installed duct work and air conditioning in my house I ran most of it in the attic and the attic smells. It smells like, I guess, really old attic, dust, old plaster etc.

So, I sealed all of the duct work twice, first with silicone RTV on the inside, and then a really thick gooey rubbery tape on the outside, everywhere. I siliconed every seam on every elbow. I also used rubber gaskets around damper shafts etc. Every where a vent penetrates a sealing I caulked around it to seal it. I also kept trying to seal the doors on the air handler and after failing multiple attempts with home made gaskets I gave up and taped them closed as well. The manufacturer claimed they would seal on their own, but it wasn't even remotely close to good enough in my opinion for a hot attic.

No smell ever, but honestly I could never imagine any contractor going through all that I did, nor could I ever imagine anyone ever wanting to pay them to. I most likely turned what would've been a 2 day job into a 2 week job.

How long has your system been running? Perhaps once enough fresh air is brought through the spaces, it'll stop smelling? Where is the unit located and where are the returns (pulls air in) located?

JimHP

We had our installer come out just for grins, they were great about our uninformed questions throughout the project. The basement is kind of damp, the brick needs scraping and sealing/painting, and there are a couple places not completely sealed from the elements (sketchy construction build-out and weird kitchen add-on, uninsulated).
Turns out I am in the basement a lot (laundry and cat litter boxes) and the smell has become something I no longer notice, until the A/C comes on on the ground floor.They told us until we get our basement sealed up (outside weeping tile or something similar) we won't lose the smell. So the source of the problem/smell won't be addressed until we get that work done, but at least we know it is unrelated to our new A/C.
I appreciate all the relies and inquiries. This site is amazingly helpful.

mattmia2

How do they figure it is getting air from the basement up in to the house unless the duct work in the basement is leaking?

ChrisJ

mattmia2 said:

How do they figure it is getting air from the basement up in to the house unless the duct work in the basement is leaking?

Chances are the filter housing leaks a lot. Most seem to, though my AirBear is pretty good I added a magnetic gasket over it's door. Most don't even seem to have a door.

I'd also assume there could likely be vents in the basement from the sounds of it.