Flexible Insulated ducting and Insulation

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chkchkka
Posts: 7
Joined: Sun May 23, 2010 1:08 pm

I have started replacing my flexible duct with insulated ducting (Dundas & Sufine) due to rodent invasion last winter. The existing ducting is a smoky transparent non insulated flexible vent duct, with spring wires. My HVAC sheet metal runs down the center of my modular home and the flexible ducting is run to the exterior walls, where the registers are. I have a heated water line (main) but that is all. No insulation on any of the water pipes. I am getting access to my ducts through the belly board and am using adhesive Flex-Mend Belly Tape where I cut. My home is supposed to have R-13 insulation underneath the sub-floor but there is at least 10-12" of air space below the sub-floor where the HVAC sheet metal runs. Closer to the exterior wall, there is 4-6” of space. I am also checking for holes in my belly board and have found several, which I have repaired. I also have gaps in the belly board around the perimeter of my home, which I am also repairing.

Will I have problems with pipes freezing since I have used insulated ducting (live in MO)? Any recommendations?

Since I have to replace my insulation due to rodents’ excrement, how much space should be between the sub-floor and the insulation? It also appears that the insulation is being supported by the belly board, no other support system.

I have a Coleman gas furnace Model DGAA070BDTA. My home is 14’ X 72’ and is 6 years old.

Any assistance is greatly appreciated.
Bill
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Posts: 100
Joined: Mon Mar 07, 2011 9:32 pm

Hi There,
I don't know the answers to the insulation questions as I am not a mobile home expert but I can help with the freezing pipe question. Yes using the insulated flex duct will cut down on the heat loss under your home. There for making it more efficient in your home. Yes it might let your pipes freeze. What i would do since you are already down there fixing stuff is just put some insulation around your pipe anyway. It wont hurt anything and might just prevent your pipes from freezing. Like i said before i am not a expert on mobile homes so i would repost this question on another forum page that might get you better results for your other questions. Might give the Mobile home repair page a try.
Hope this helps.
Bill
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chkchkka
Posts: 7
Joined: Sun May 23, 2010 1:08 pm

Thanks Bill for getting back to me so quickly. I appreciate what you shared, and will post another question in another forum.
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Greg
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Posts: 5696
Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY

Let's approach this logically, I am not sure if you are replacing ALL of the ducts or just the flexible ducts. You need dead air space between the floor & belly, this will (should) stay warm in cold weather. Since the pipes run through the area they should stay warm as well. Insulating the pipes COULD be a double edge sword. You are insulating from the cold, but you are also insulating from the heat.

The best advise I can give is Skirting with no holes (insulated if possible) and a Belly wrap with no holes.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
chkchkka
Posts: 7
Joined: Sun May 23, 2010 1:08 pm

Thanks Greg. When you say "Dead Space", how many inches would you define this as? What type of insulation would you recommend, and what R-value? If I use batt insulation, should it be un-faced batt?
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Greg
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Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY

I personally don't think you can have too much insulation, but It can get cold here. I believe Mark used fiberglass batts in plastic and let it hang just behind the skirt panels. He is in N. Dakota and claims that the temperature never goes below 32* under his home.

At a minimum I would go with what ever the R value recommendation for you area is. Remember the big thing is NO air leaks and keep the skirting as tight as possible to keep both air & critters out.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
chkchkka
Posts: 7
Joined: Sun May 23, 2010 1:08 pm

Thanks again, Greg. Mark seems to have the right idea! I'm trying to visualize exactly what he does with the insulation....and would appreciate some pointer from him on how he keeps his temperature @ 32*.

I read the book, "Your Mobile Home Energy & Repair for Manufactured Housing" and it didn't indicate how much "Dead" space should be between the subfloor & the insulation/belly board.

I thank you in advance for all the assistance given on the forum.
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Greg
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Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY

I don't think the amount of dead air space is critical as long as there is some. As long as the area is sealed & insulated it will stay warm.

My understanding of the way he did it was by using plastic sheets and nailing one edge of the plastic to the top rim joist. Lay the insulation in the plastic, fold the plastic over and nail the plastic back up creating a bag of insulation. You could send Mark a PM and ask him. I used rigid 2" foam insulation on ours last year, it did make i difference last winter.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
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