Name of the white goop on fiber ducts
CombatRescue
| Posted in Energy, Heating & Insulation on
Hi all,
I’m in Florida and most of my A/C ductwork is rigid fiberglass boards covered with a kind of white paste. There are a couple of small leaks near the air handler that I’d like to repair, but foil tape isn’t doing the job – I’d like to get some of this white goop to make the fix. Can some one please tell me what this stuff is called?
Thanks!
Andy
Replies
I'm pretty sure it's called mastic.
I've never used it myself, I've had it strongly recommended by some HVAC pros. Haven't gotten to the point of actually moving the ductwork yet though, so I haven't tried to buy any yet. I'd assume anyplace that installs ductwork would be able to sell you a tub of it.
Mastic... HD carries it... Caulk tube or bucket... Serveral different kinds and viscosities.
Clean the duct surface before installing with denatured and use the mesh tape.
Who ever invented work didn't know how to fish....
Thanks all! Just what I needed to know!
Andy
I'm in a similar situation except someone before me tried to coat the thing with a roofing cement on the foil backed fiberglass rolls that were wrapped around the handlers.
Would a primer serve as a blocker to keep the oil from the roofing cement from bleeding thru to the elastomastic product?
Is it hard board or flex?
Who ever invented work didn't know how to fish....
Or is it insulation wrap.
Who ever invented work didn't know how to fish....
Fiberglass insulation wrap I believe.
Standard spun fiberglass on a foil backing with a plastic weave netting involved in there.
The installers had left a pile of debris on the roofs and there amidst the sheet metal remnants, roofing cement paraphernalia and empty beer bottles were some left over fragments of the wrap from a year or two back.
There are 11 air units on these four low pitched metal roofs which are joined together with what looks to be custom fit gutters which sometime go uphill. Don't roar.
Some units were placed in the middle of the slopes with no crickets to direct the water. Seeing the quality of the installations I would wager a guess that there is no flashing and it looks like multiple coats of roofing cement were used as the 'do all' sealer to stop water entry at the penetration points.
The drains were left open with no pipes directing the condensation to the gutters which has now begun to wear the galvanized coating off and the early stages of rust in that stream are now showing. Long lengths of unsupported gas piping.
So now I have the fun of trying to fix the boogers and stop or slow down the leaks. I believe about every unit has some kind of leak showing up every now and then.
Sure hope this elastomeric white rubbery products works as good as they claim.
A local roofing supply house handles two products 'Topcoat' and 'Paramount'. I was quoted $115 a five gallon bucket over the phone. It seems I recall the big box price for their similar product at a lot less but it's been awhile.
I'm curious if one product might be more durable over another.
This assuming you have metal duct work with wrap insulation.
Scrap the old wrap and start all over again. There is an ungodly amount of insulation in a roll. You may get by with one roll. Choice of R factors. The rolls are 150 or 600 sf for R5. 15 or 75 bucks each. 1st choice - use the sheets (3x4') and not the roll. A little more $ but more gooder stuff. 96 or 144sf to a carton.
There is an exterior grade mastic (pookey) at about 16$ a 1-1/2 gallon bucket. Use it with the nylon mesh.
Put the new insulation on (spots of 3m spray adesive is a great 3rd and 4th set of hands) Clean (denatured) the seams or joints or where ever you put the reinforced 3 or 4" wide foil tape. Put the tape on using a squegee. Paint The tape joint with the mastic with the pookey. Over lap a couple of inches.
1st coat of mastic then the mesh tape and then a 2nd coat of mastic. 3rd coat doesn't hurt a thing. Same for a 4th.
This assumeing it is flex.
Cut away the roofing cement and foil. In the interior of the flex is a wire wound plastic sleeve. Make sure this firmly attached to the crown or starter collar. A cable tie (they come in lenghts to 60" for this job) works wonders. Make sure there is a couple of layers of duct tape under the tie before you crank it down. Duct tape over the tie. You are going to have a taped and mechanical joint.
Now make sure the insulation is put neatly back. Wrap bare area with your reinforced tape. Squegee. 2nd cable tie. Do the layered mastic / mesh tape deal.
This is assumeing you have stanard fiberglass duct board.
Carve away roof cement without getting too destructive. Clean the rest up as best as you can (paint thinner). Repair missing or damaged foil with reinforced tape. Do your pookey thing.
The squegee helps fuse the tape in place.
'Topcoat' and 'Paramount'. - Elastomeric. Big box has it for 45$ for 5 gallons.
Roofing stuff. Does not do well with duct work.
Drains....
Traps and vents. 3/4 sch 40. Paint it for UV protection.
Who are your AC supply houses? Might be able to link you up.
Who ever invented work didn't know how to fish....
Thanks IMERC- Called the roofing supplyhouse again thinking maybe I'd heard wrong about the topcoat price. $105.10.
That great of a disparity between the HD/Lowes prices made me wonder about the quality of the bigbox material thinking maybe it is some kind of different version.
That or the supply house just like to eat well.
On the rusting galvanized metal roof, since the rust is just starting would the paint made for covering over rust without sanding in order to form the desired bond work here? And then cover with a metal roof paint?
At a guess the supply house is charging you list for topcoat. My supply house here wants 61$ for 5 gal. Henry brand roofing elasto is some pretty good stuff.
Don't use the roofing stuff on the duct work. Was that your plan? Pookey and elasto are not the same stuff.
As far as the rusty metal goes.... Clean it up (wire brush) and use some CRC Zinc-it cold galvanize. Hot dip in a can. The CRC comes in aresouel or gallons. More good stuff. real easy to use. Lasts long time.
Graingers and electrical supply houses usally carry CRC prouducts.
Who ever invented work didn't know how to fish....
Thanks again.
Since were on the subject... :o)
Condensation drains. Schedule 40 3/4 inch ok.
What about the necessity of a trap on the condensation drains?
Was recommended to me and I see a warning sticker on the units saying it was necessary. Just 'cause no one else I see does it I don't want to neglect it if needed for proper drainage.
Any advice?
Thanks again.
Green and over his head?
Yes..
If you want use 4 el's to make up your trap. Put a short vent stack (riser maybe 6"long) in the system. Come off the unit w/ your trap. Put a T on the downhill side. Put in your riser off of the T.
Comes in handy if you have to clean out the line and you're not so likley to get air lock.
Spray paint the PVC for UV protection (light color). Avoid high pressure el's if you can. Angle of the el is too sharp, collects crud quickly. Go with a long as you can get your hands on sweep. Use a "hot" glue (blue or red) and not clear. Clear just dosen't hold up well in that enviroment.
Everything you need is at the AC wholesaler if you have access.
Keep in mind everything in the last several posts cost more to do but the methods of repair should last a lot longer with less chances of call back.
Where are you?
Who ever invented work didn't know how to fish....
Rez... If you use the CRC... (still the best fix)
READ THE CAN!!!!
Who ever invented work didn't know how to fish....
CRC? Can't Read Correctly??
In Tulsa Ok. Hot roofs.
CRC= brand name as in CRC industries. Warminister, PA.
Part #02081.
Which AC wholesaler you want to use.
Gave up hot roofs in '64. Kicked the habit just fine.
Who ever invented work didn't know how to fish....
I think I'll write a book,
'101 Reasons Why I am not a Roofer.'
What does roofing have to do with AC ducts unless yur going for a cool roof???
Who ever invented work didn't know how to fish....
Well, everything is such a mess up there I just call it all a roof and wing it.
Think I'm going to tell the owner I'll try to locate him a reliable AC guy. He's been jacked around so much by the unscupulous sort he's gunshy.
A cold roof. Now there's an idea!
It is a water based "mastic" used to seal duct work. It stays flexible and is used inside and out. I used to get it at HVAC wholesale houses in one gallon buckets. We used to put it on at the end with heavy rubber gloves which allowed it to be smoothed out. Lowes sells a version of it. Just don't use asphaltic based mastic.
Thanks all, picked some up at Lowes today and it's just what the doctor ordered!
Andy