Do I re-do or buy a new HVAC distribution box???

6BangBronk

6BangBronk

Well-Known Member
Joined
Jul 15, 2005
Location
Durham
Working on my barnhouse built in 1920 and soon to either be a house or completely bankrupt me one or the other...

I have replaced everything but last remaining category being HVAC. I pulled all the old flex out this weekend to find my metal distribution box was full of mouse shit. :eek: The HVAC Engineers here tell me they are all custom made that you just don't go out and buy one off the shelf. It is a 2' fabricated square with boots for (1) main line (forgot to measure - something around 16-18") and (8) 6" runners out the sides. HVAC is all new to me (being why I procrastinated it to be last).

1. Can I replace the insulation in what I got? I notice it's held with large rivets?
2. Is there some sort of "foam product" that I could just tear out my old insulation and spray the inside with and roll? I know area restriction would probably hamper the purpose so I wouldn't want a product that expanded so much...
3. Or do I need to start all over and possibly just re-use my old boots?

I'm kinda lost for direction being I don't want to "have plans drawn for a contractor to construct". But I don't want to half-ass and have to revisit this in the near future either but I'd like to get this behind me ASAP.

Then, finally after 5 long years of throwing money and time I might be able to call my barnhouse a livable house...

Any help would be appreciated.
 
Remove old insulation, clean and sanitize, wrap out side with R8 duct insulation.
 
regardless of what you do, get rid of that insulation inside the box.

boxes are cheap and easy to make by a competent sheet metal fabricator. So, make new for something easy or spend a few extra hours cleaning up some mouse crap and sanitizing.

Wrap the box with good insulation AFTER you paint the seams with mastic. Make sure you seal every joint as much as possible to make it as efficient as possible as it will keep condensation down to a minimum and will increase efficiency.
 
Well a unanimous consensus is always awesome... I'm the mouse shit cleaning type before I try to make something difficult and spend more money than needed. Clorox kills everything including AIDS....

And the insulation will come right out. The mice gave me a pretty good start.

Thanks!
 
Part of my job is doing duct cleaning so I see this a lot. Old metal trunklines tend to get dirty over time but the metal itself really doesn't go bad. The insulation on the other hand at best will only last 20 years. As said above, clean, sanatize and reseal what appears to leak air (usually around the seams) and reinsulate. If its structurally sound it'll be obvious. Do be careful if you see white or offwhite tape around the seams because that's actually asbestos. It may not have screws holding the pipe together and if it doesn't it would be beneficial to add a few to make the trunkline stronger as a whole.
 
The boots are held in place with triangle tabs that are actually part of the end of the boot. Tedious to say the least if ever had to build one like that. But I will give this thing a good workout to make sure it's good to go!

HVAC system itself ain't that old. Just that the house was built on the ground without a crawl space. I figured they scratched heads and wondered why they would ever want a "crawl space" back in 1920. :lol: Even the plumbing vents are external up the sides of the house. But all the flex was fished through and laid on the ground when it was added. The D-Box was only item in the air with a trail dug to the side of house to get it in there. So it was a perfect mouse playground.
Now! House sits about 11" higher with about 15-20 cubic yards of dirt shoveled out. :( Seriously! Dug another cube out last night. Got it down pat with a concrete flat bucket strapped with a rope around it with a loop to put on back of my lawn mower. House now has solid foundation and plenty of screen vent.

New flex going back in hopefully this weekend along with my D-box addressed as mentioned. Good thing is rain does not slow this job down much.

Thanks again for all the advice!
 
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