I was volunteering out at our Scout Camp on the weekend tearing apart a cooler for one of the kitchens.
In this neck of the woods, in house construction, we put the vapor barrier on the warm side of the insulation. Would that logic apply to a refrigerated cooler as well? Or should there be a vapor barrier on both sides of the insulation?
One of the walls is on an outside wall and the other is inside the heated building.
They used fiberglass insulation in the walls and ceiling. Should they use styrofoam?
Thanks.
If it wasn’t for the Bank Payments,
Interest, Taxes, Wages, and Fuel Costs,
I wouldn’t have to charge you!!
Replies
First off, thanks for volunteering for the Scouts.
Vapor barriers always, always, always go on the warm side. Never use two vapor barriers. And yes, styrofoam will provide more R per inch than FG, and be more forgiving of moisture issues.
YIS,
Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
When you say "warm side", don't you really mean, toward the conditioned space?
If it was 100F outside and 75F inside, then the "warm side" is outside (summer);
then in the winter when it is 40F outside and 70F inside, the vapor barrier would be wrong.
Is there remote controlled vapor barriers out there? Neat concept.
Anyway, .....
Grunge on.
Ya, that's what I was wondering about. So why not vapor barrier on both sides?
If it wasn’t for the Bank Payments,
Interest, Taxes, Wages, and Fuel Costs,
I wouldn’t have to charge you!!
No, I meant the warm side. Sometimes, that's the outside. Sometimes, there is no right place for a vb. You just assess the situation, and put where it's warmest most of the time.
The key to understanding vapor barriers is understanding moisture drive. Moisture moves from warm to cold and from wet to dry. Sometimes, it's a judgement call where the vapor barrier should be. Often, the perfect place varies with the time of year, and if that's the case, you probably should skip the vapor barrier and build an assembly that can wet a bit, and then dry out.
You never use two vapor barriers because that's a recipe for rot. Here's the thing - If you could make two perfect vapor barriers, you'd be fine. That's just not going to happen on a job site. A lab, maybe. Water vapor is at a higher energy level than liquid water, at the same pressure. It's more active, and more likely to get through cracks. Air can move a lot of moisture if you don't seal perfectly. Once it gets in, and if it hits a cold surface, vapor condenses to liquid. Liquid water isn't getting out from between two vapor barriers. For it to do so, generally you'd have to add enough energy to vaporize it, which isn't likely to happen. More likely is that the first part of the cycle would repeat, and you end up with more and more water.
With a cooler, I think you're safe with one vapor barrier on the outside. If you insulate with closed cell foam such as xps - the pink or blue t&g stuff, and seal it well with expanding foam, I doubt any other vapor barrier would be warranted.
Stopping air movement, btw, is far more important most of the time than the presence or absence of a vapor barrier. Air can can carry huge amounts of water through a small hole, while vapor pressure is a relatively weak force.
http://www.buildingscience.com
Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
Edited 4/6/2006 10:21 pm ET by Andy_Engel
Thanks Andy for your insight.
I have a feeling my repairs this weekend will be temporary. There is a big event happening the first weekend in May, and everything needs to be up and running.
I believe that the refer unit is an older unit so it may warrant a total rebuild of the cooler when they replace the parts inside.
I assume by your first reply that you are a Scouter. I have been involved for about 11 years in the Beaver, Wolf Cub, and Scout programs.
YIS, Mike V.
If it wasn’t for the Bank Payments,
Interest, Taxes, Wages, and Fuel Costs,
I wouldn’t have to charge you!!
Yes, I am a Scouter. I've been involved for about 7 years now: one year as Webelos leader but mostly as an ASM. My friend who's been SM all this time is making noises about stepping down. That will most likely make me SM, but man, I'm really going to miss swapping the same old stories around campfires with him. It's not just the kids who make their best friends in Scouts.
Busy weekend for us - Tomorrow is our annual roast beef dinner, the major fundraiser we do. We'll be working from about 8 in the morning until about 10 at night. If you find yourself in Roxbury, CT, stop in!Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
Yes you are right. I have gotten the opportunity to work with some pretty amazing people. It's also net seeing kids which you saw when they were six or seven, now 16, holding down jobs, etc.
The thing that gets me is when they say hi Akela, or hi Scouter Mike.
Have you done a Part 2? I am not sure what they call it south of the boarder. I have done my Part 2 in Beavers and Wolf Cubs. The trainers and candidates were an awesome group of people.
Does your Scout Troop do any summer trips at all? We always get at least one Troop up from the states and sometimes one from overseas.
http://www.victoria.cascadia.scouts.ca/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=12&MMN_position=21:21
Mike.
If it wasn’t for the Bank Payments,
Interest, Taxes, Wages, and Fuel Costs,
I wouldn’t have to charge you!!