Condensation on exposed furnace ducting

[Bradley Miller]

Does anyone have some suggestions for exposed furnace/ac ducting in summer heat/humidity? My garage (1982 era) has exposed duct work and it sweats when I have the door open. That'll be bad news when I take the car (1962 Buick Special Deluxe with V8) to sand down and do body work. I'd box the entire thing, but I would run into pipes for plumbing and plugins for garage door openers. I don't know if there would be a way to glue some insulation to insulate the duct work??

[larry4406]

I would think you should insulate the exterior of the ductwork with the silver foil style blanket insulation. It is about 1/2 inch thick available at home depot/lowes. In the houses i build, the heating contractor has us insulate all ductwork that runs through areas that are not climate controlled.

The basement trunks are not insulated and sweat like mad when the units are first fired up in the summer.

[dave in tn]

The hospital where I work, We had a problem with water leaking into the patient room in the summer. We found the ductwork exposed in the places where it was leaking. We fixed the the places and that fixed the problem. It will still drip sometimes from the grill depending on the humidity. Dave

[Lu47Dan]

I agree with larry If you can't get it at homer depot , look in the yellow pages under insulation suppliers , these places supply to the contractors that do industrial and commercial jobs , you can get some good info from them and they can tell you the best thickness for your areas . Wrap the whole duct and tape all the seams or you will end up with a bigger problem them you have now .

[87SS]

Since this falls right in my field here goes.

first seal all seams with duct mastic.
after your seams are dry apply duct Wrap completly aroun exposed ducts.

not only will this keep your heat/cool air in the duct till it reaches your registers It will eliminate your condensation issues.

if you can't find duct wrap at you boxstore... hot water heater blanket is the same thing;)



we attach our duct wrap by using a Arrow P-35 stapler. wrap the duct then staple the ends together
http://www.tooled-up.com/artwork/ProdImage/TB14003.jpg

mastic
http://oikos.com/products/mechanical/rcd/
http://oikos.com/esb/42/airdisproj.html

Duct wrap
http://www.owenscorning.com/comminsul/products.asp?product=10

[Lu47Dan]

Hey An insulator . I am a Fitter . Was my advice sound ? Dan

[87SS]

weatherization contractor actually;)

yea your advice was on target.

without knowing his climate it's hard to recomend a R value.
a R-6.7 should do the trick:)

[Bradley Miller]

Great info guys! Thanks! My ducts are already up, and they're attached to the joists, the sheet rock/water pipes/etc.. butt right up to it. Do I need to worry about wrapping it all the way around? Can that stuff be glued on or that?

[87SS]

Great info guys! Thanks! My ducts are already up, and they're attached to the joists, the sheet rock/water pipes/etc.. butt right up to it. Do I need to worry about wrapping it all the way around? Can that stuff be glued on or that?

the best way would be all the way wraped BUT... I have ran into situations like yours.

what we do is wrap what is exposed & attach/hold it in place buy placing
1x3's (furring strips) along the top of the sides using 1 1/2" zip screws (1/4 hex head sheet metal screws)

[Bradley Miller]

Cool -- great idea. I'll look into getting that and seeing if that will take care of my sweating ducts, and maybe help my heat/cooling bills.

[Willy Victor]

Brad here is a way to hold insulation to a duct when it is in a tight spot. Use stick pins and speed clips. Stick pins come two ways. One is peel and stick, the other is perforated in which case you need an adhesive. We use tough-bond similar to liquid nails only it comes in quart or gallon cans. You dab a little adhesive on the pin and stick it on the duct. Duct must be clean and dry, wait 24hrs for adhesive to set. Cut your duct wrap to fit, place insulation on the duct piercing the pin, then put on the speed clip. With nippers or side cutters cut the excess off the pin. If this sounds confusing it really isnt. The stick pin is two inchs square, perforated light gauge sheet metal with a nail in the center. The nail comes in different lengths for different wrap thickness. The peel and stick is what the name emplies. Peel off the release paper and stick. If you have an insulation supply house near you they will know what I am talking about. Hope I have been of help. Insulating your ducts will definitely stop your condensation problem.

Willy RET. Pipe Wrapper

[Bradley Miller]

Many Thanks!!!