I have a question that I think will best be answered by Denalipilot. The answer may just save you some trouble so I will ask it here in your thread.
I am in the process of setting up my spray booth. This means that a large metal duct will have to exit the building. I decided to run my duct from the heated studio into the cold attic space and out of the building through automatic louvers. I thought that this would have been the best way out of the building. I may be wrong. The cold air that is coming through the duct and the cold being conducted through the meat is resulting in crazy condensation on the duct in the heated studio space. This makes sense but it is a problem that i have to solve.
I think I may have been better off keeping the duct in the heated space and exiting the building with the automatic louvers. Then if I build an insulated door to cover the louvers then I think the whole system will be in balance with the heated studio and there will be no condensation. Does this sound right?
I have the same problem but on a much smaller scale when the EMT conduit travels from the heated studio into the cold attic. Is there a product that can be used to reduce the conductive nature of metal? If I had it to do over I would have switched to PVC conduit at the ceiling...too late now
Thanks
Studio Condensation Issues
Moderator: crzypete
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DenaliPilot
- Posts: 63
- Joined: Thu May 17, 2007 8:22 am
- Location: Denali, Alaska
Hi Nektai,
I wish I had more experience to offer in this department. Our commerical buildings are summer-only, and our winter homes lack attic spaces for the most part. Also, interior Alaska tends to be incredibly dry in winter, so our problems have more to do with finding ways to humidify our air. Here's a couple blind, groping thoughts for what they're worth:
1. re-routing the ductwork through the warm space makes sense to me, as does PVC or ABS transition. Even if your roof penetration is a done deal, could you cut out a run of metal ducting and replace it with plastic using fernco rubber pipe connectors?
2. could you easilly construct an insulated space around the existing duct that is in the cold attic space? (maybe fiberglass insulation wrap, spray foam, or a whole framed-out utilidor?) I would think any small amout of air circulation in your duct would then tend to keep the entire duct warmer.
3. not sure how effective the automatic louvres are at keeping outside air from infiltrating. many thermal mass home fireplaces have tight-sealing chimney caps that really eliminate air passage when you are not using your chimney to have a fire. several designs exist for opening/closing these caps from indoors by use of a cable and spring-loaded cap. My brother has one of these that Pete is familiar with.
Good luck with it, I'll definitely check out your studio updates on MJ to see what you come up with.
-DP
I wish I had more experience to offer in this department. Our commerical buildings are summer-only, and our winter homes lack attic spaces for the most part. Also, interior Alaska tends to be incredibly dry in winter, so our problems have more to do with finding ways to humidify our air. Here's a couple blind, groping thoughts for what they're worth:
1. re-routing the ductwork through the warm space makes sense to me, as does PVC or ABS transition. Even if your roof penetration is a done deal, could you cut out a run of metal ducting and replace it with plastic using fernco rubber pipe connectors?
2. could you easilly construct an insulated space around the existing duct that is in the cold attic space? (maybe fiberglass insulation wrap, spray foam, or a whole framed-out utilidor?) I would think any small amout of air circulation in your duct would then tend to keep the entire duct warmer.
3. not sure how effective the automatic louvres are at keeping outside air from infiltrating. many thermal mass home fireplaces have tight-sealing chimney caps that really eliminate air passage when you are not using your chimney to have a fire. several designs exist for opening/closing these caps from indoors by use of a cable and spring-loaded cap. My brother has one of these that Pete is familiar with.
Good luck with it, I'll definitely check out your studio updates on MJ to see what you come up with.
-DP
OK, here’s my 2 cents Nico.
I was sittin’ on the couch one Sat. morn surfing through the channels on TV when I happened upon “This Old House”. For me, it’s interactive TV. I like to sit there, talk back to the guys and say “Yea, sure you can tear out the entire side of that house because you found some dry rot on one board at the corner…IF MONEY’S NO OBJECT !!! Here in the real world…” But I’ve digressed. Anyway on this episode this guy was having a problem in his shower. It seems that when he took a shower and turned the shower vent on, after a few minutes, cold water would start dripping out of the vent onto his head. The problem only happened in the winter. Peculiar huh? This homeowner wasn’t exactly the sharpest knife in the drawer. So anyway, whichever TOH guy that was there, we’ll call him Sherlock for the purposes of this discussion, decide to investigate the mystery at the source. In the attic we go, camera crew and all. “Elementary my dear Watson”. It appears we have some uninsulated flex duct leading from the shower vent to the roof, through the cold attic space. The hypothesis is that the warm moist air is entering the cold duct, condensing on the inside walls and running back down to drip on our unsuspecting drip. Solution: insulated duct. Voila, another mystery solved. Let’s put on our smoking jackets and retire to the study.
All right, I’ve gone ‘round the bend.
I do think that if you get some fiberglass insulation and wrap your ductwork, like DP said, it should solve your problem. You know, like that McDonalds burger, keep the hot hot and the cold cold. I don’t think PVC would’ve fixed it either. I get condensation on my A/C drain pipe because the water running through it is cold and the surrounding air, which is open to the attic, is very hot.
Anyway, I don’t know if this was helpful, but I hope it made you smile.
Stephen
P.S. Thanks for the boat advice. Test is right on, money cuts this weekend.
I was sittin’ on the couch one Sat. morn surfing through the channels on TV when I happened upon “This Old House”. For me, it’s interactive TV. I like to sit there, talk back to the guys and say “Yea, sure you can tear out the entire side of that house because you found some dry rot on one board at the corner…IF MONEY’S NO OBJECT !!! Here in the real world…” But I’ve digressed. Anyway on this episode this guy was having a problem in his shower. It seems that when he took a shower and turned the shower vent on, after a few minutes, cold water would start dripping out of the vent onto his head. The problem only happened in the winter. Peculiar huh? This homeowner wasn’t exactly the sharpest knife in the drawer. So anyway, whichever TOH guy that was there, we’ll call him Sherlock for the purposes of this discussion, decide to investigate the mystery at the source. In the attic we go, camera crew and all. “Elementary my dear Watson”. It appears we have some uninsulated flex duct leading from the shower vent to the roof, through the cold attic space. The hypothesis is that the warm moist air is entering the cold duct, condensing on the inside walls and running back down to drip on our unsuspecting drip. Solution: insulated duct. Voila, another mystery solved. Let’s put on our smoking jackets and retire to the study.
All right, I’ve gone ‘round the bend.
I do think that if you get some fiberglass insulation and wrap your ductwork, like DP said, it should solve your problem. You know, like that McDonalds burger, keep the hot hot and the cold cold. I don’t think PVC would’ve fixed it either. I get condensation on my A/C drain pipe because the water running through it is cold and the surrounding air, which is open to the attic, is very hot.
Anyway, I don’t know if this was helpful, but I hope it made you smile.
Stephen
P.S. Thanks for the boat advice. Test is right on, money cuts this weekend.
Steve, you crack me up. I like to yell at those guys too.
I have experienced condensation issues as well- So much moisture in the air- and with the heat on such a change in temperatures. I had plastic sheeting over the attic truss opening- water was condensing on it and dripping down- serious amounts of water. I hopefully fixed this with a sheet of 2" rigid foam.
Similar issues with the pvc pipe and the air intake for the furnace. I may need to talk to my plumbing engineer about this- it is forming a puddle in the base of the furnace.
If you had questions as to this post- yes I split it off of my studio progress- it is worthy of its own thread.
Pete
I have experienced condensation issues as well- So much moisture in the air- and with the heat on such a change in temperatures. I had plastic sheeting over the attic truss opening- water was condensing on it and dripping down- serious amounts of water. I hopefully fixed this with a sheet of 2" rigid foam.
Similar issues with the pvc pipe and the air intake for the furnace. I may need to talk to my plumbing engineer about this- it is forming a puddle in the base of the furnace.
If you had questions as to this post- yes I split it off of my studio progress- it is worthy of its own thread.
Pete
This is exactly why I love spray foam so much. I sprayed every pipe and every piece of ductwork with 3" of the soy based foam. Not only does it eliminate the condensation problem, but it also reduces the noise from plumbing and the rattle/echo in ductwork. My only regret is that I didn't do all the pipes and ductwork in the basement. I've been seriously considering dusting off the proportioner and going back for another pass at it.
I know, I hear that one and the "what if I need to fish a wire in the wall?" all the time. Either way, you're opening the wall. Either way, you're ripping out insulation. It is a bit messier, but in the end it's the same method for finding leaks. That said, I've never seen or heard of a situation where this had to be done. I have been on several jobs where we had to rip out substantial insulation due to design flaws in the HVAC system. This isn't much of a problem with the open cell insulation, but it can be a major undertaking with the 2LB foam.