Comments on: What’s Causing the Moisture Problem in This Trendy Restaurant?

By: Mohamed

Mohamed — Mon, 23 Mar 2020 20:19:29 +0000

As long as there is a leak in
As long as there is a leak in the cold air between the suspended ceiling and the diffuser, then there will be an condensation for air or maybe there's problem in insulation of diffusers plenum box.

By: Jackson

Jackson — Mon, 06 May 2019 17:44:59 +0000

I just went to this
I just went to this restaurant today and immediately thought of this post when I saw little table tents saying that condensation is normal in this humid climate and not to worry about drips on your plate. Interestingly, I saw black spots around some of the light fixtures and ceiling sprinklers, which would seem to support your hypothesis of outdoor air entering the ceiling above. Seems it might be worth another visit Allison!

By: Pete Baston

Pete Baston — Fri, 20 Oct 2017 01:04:02 +0000

Drywall never lies , maybe we
Drywall never lies , maybe we use it so that it provides a constant litmus test for building problems for all to see , look for some bright student to build tell tales to visually report this stuff .

By: Dennis Johnson

Dennis Johnson — Mon, 16 Oct 2017 03:38:39 +0000

I have seen this before and I
I have seen this before and I also thought kitchen heat rising to ceiling registers, but it in my first cases it was only along the windows so that did not fit. Ultimately, I taped about 24 inches of cardboard over the top of the windows and guess what no condensation. Then I thought, just like through car windows hot days cold a.c. and you have condensation on both windows and diffusers. The sunlight was coming through the windows at times during the day and causing intense heat build up along the ceiling near the diffusers and when the cold air was discharging it had the potential for a mini-storm. Now I just close curtains, If available and run a while to check. It can likely be other things, but this is from actual experience.

By: Lorne McIntyre

Lorne McIntyre — Thu, 21 Sep 2017 12:09:26 +0000

Great newsletter Dr. Much
Great newsletter Dr. Much like you I find myself looking structures differently now since my first building science seminar only a few years ago. I love summer camp and have had the privilege of attending the last two years. I’m far from an “expert” but as a restorer I inspect hundreds of buildings each year and see this issue from time to time. I agree with you Dr. The negative pressure you describe can be pulling warm wet air into the conditioned space in a high amount due to leakage, flowing across the cooler surface of the diffuser, air condenses at surface of diffuser because it’s at dew point temperature or below, pools on the surface just enough to touch/wick into drywall and if this condition is on going likely to form some level of microbial contamination in this area. I am amazed how much leakage can negatively affect a building. Thanks for the newsletter and keep running.

By: Henry Slack

Henry Slack — Tue, 19 Sep 2017 19:55:46 +0000

Alison – Nice pix!. I think
Alison – Nice pix!. I think this is unsealed ducts blowing cold air at the wall board, thus condensation (and mold). That’s why you see big spots on just one side of the diffuser (or both). Moist attic air might be entrained to blow on it, too. Fix it by sealing the connection with mastic, then duct tape. It’s probably only got tape which has dried out and let the cold air out.

By: Julian Ganoudis

Julian Ganoudis — Tue, 19 Sep 2017 14:58:02 +0000

I like that Allison mentioned
I like that Allison mentioned capture efficiency, which is really important. Restaurants are a complex beast! Balancing the hoods (ranges, dishwasher, ovens) with the HVAC system is always a challenge and rarely ever right. Even if it is balanced, there are so many things in play that can change that equation, kitchen doors left open for example, steam tables, etc. In this example, it is almost certainly mold growth on the drywall surrounding the diffuser as the drywall becomes more saturated from condensation. Whether the condensation is from the supply ductwork in the chase (bulkhead), which is typically metal for this type of diffuser, or from the bottom of the diffuser, requires more information. My guess is that it is from the top too. Could be outside air infiltration in the chase or poorly sealed diffusers with the ductwork. I favor the latter since the problem exist in a different location with the same type of diffusers. Perhaps less likely, but maybe a contributor, is heat gain from the adjacent windows.

By: Scott Ranck

Scott Ranck — Tue, 19 Sep 2017 10:43:51 +0000

Great article. I do the same
Great article. I do the same thing when I go into buildings. I've found many restaurants with oversized AC equipment allowing the humidity to creep up. Also, not enough make up air for the kitchen vent as you discussed.

By: JC

JC — Tue, 29 Aug 2017 01:39:57 +0000

Dr. Allison,
Dr. Allison, I think your services are needed at the new Falcons Stadium. Apparently there are some leaks from the ceiling and I think may be condensation from these huge HVAC supply vents in the ceiling.

By: Andy Wahl

Andy Wahl — Sat, 26 Aug 2017 15:38:28 +0000

Who is going to approach the
Who is going to approach the owner and get paid to fix this issue?