Well, let me be the 1st to say "you should have called a pro". Be prepared to hear that about a dozen more times.

Ok, enough sarcasm... I'd go with mastic (aka pooky). Silicone is somewhat messy (at least when I put it on), some of it can really stink, and it's somewhat time consuming to put on.

Mastic gets smeared on with a cheap paint brush, doesn't really smell and cleans up with water.

About the only time I use caulking to seal duct is if it's going to be exposed in some fancy building (mostly commercial). If it's in a residential setup and exposed, I still pooky.

 

What kind of Duct is your company installing on this job?

The company I work for uses about 4 wraps of packageing tape
on flex

 

sealers and there applications

CT2.Your kiding right.Just yanking are pee pee maybe.Just joshing around with us RIGHT.....Packageing tape? Are you talking the clear stuff or the brown???

jhcrowman. In regards to sealer applications.I use silicone on the furnace or air handler sets.For one and only reason.Aesthetics.Yes, Silicone can be messy.It will get every where if your not very carefull.But a clear silicone looks SOooo much nicer.alot more professional than a bunch of grey or white pasty looking stuff smeared all over.I did one time have(get this guys)a inspecter all most tag me for using silicone on the sheet metal.Why you say? Well in the galvinized sheet metals manufacturing companys specification sheet he had at the office.It said silicone will etch the galvinizing!!!!!. WELL we would'nt want that now.Well as it turned out he was a really nice guy.He was going to LET me slide just this one time.Anyway silicone on the furnace and air handlers and any exposed take offs.Mastic on all the ducting seams.Also the mastic you can buy at the big boxs of this world works just fine.
41GASMAN

 

You should have called a pro right

I like silicone,mastic is very messy.

 

On metal duct, silicone. On duct board, mastic.

 

The only time I've used silicone is to seal the gaps where copper goes into the A/H. I've never used it to seal duct...but that's just my experience.

[Edited by square2round on 03-10-2005 at 09:58 PM]

 

I've never used silicone for sealing. That's just my experience.

So what do you use silicone,mastic or tape?

 

Re: sealers and there applications

CT2.Your kiding right.Just yanking are pee pee maybe.Just joshing around with us RIGHT.....Packageing tape? Are you talking the clear stuff or the brown???

I think that he is talking about that UL 181 listed Mylar tape that you use for the flex connections. It looks and feels just like packing tape, but it is black and has the UL181 listing on it.


As far as Silicone is concerned, I HATE it when I have to changeout a furnace that has been siliconed....Bloody murder trying to scrape all that stuff out to get the unit free from the can....Arrgh..
I actually use foam weatherstripping for the furnace connections, and for my sheetmetal joints, they are S and Drive connections with a layer of foil backed mastic tape on the seams, including my round WA pipe stuff... That mastic tape is the best, no mess no fuss (except for that blue liner tape on the mastic you gotta pick after you make the joint...
They sell it at the box stores as well... Kinda expensive but well worth it.

[Edited by oloenneker on 03-10-2005 at 10:03 PM]

 

have used aluminum type stuff before made by alcoa,...comes in a tube and when it sets up..........good-luck trying to get it apart.Blends in nice with the metal too.As far as preference,.....i don't really have none one way or the other.Both work just fine......

 

I've never used silicone for sealing. That's just my experience.

So what do you use silicone,mastic or tape?

I use tape and mastic. It may be overkill, but I feel better.

 

I've never used silicone for sealing. That's just my experience.

So what do you use silicone,mastic or tape?

I use tape and mastic. It may be overkill, but I feel better.

I use to do that to but then I tried silicone,I love it.

 

silicone

Has anyone read Bryant's white paper on evaporator coil
failures ? one of the main culprits is acetic acid.
Go to the site and read up
thanx

 

Can I use silicone to seal the holes where wires go into the air handler? I have read that silicone while curing can mess up electronics if you put it directly on copper, because of acetic acid, but the wires are insulated.

 

I've done that several times, works really good when you don't have any gromets to keep the wire from getting chaffed.

It will be a PITA to get new wires in, or old wires out of that, so use it sparingly.

One more thing, if there's no air leaking from the holes where the wires go through, you probably don't have to worry about sealing it up tight though. If you're worried about the wires getting nicked on the case of the furnace, just get a grommet or split a piece of small hose to use as a makeshift grommet.

 

I use the 3" mastic tape on metal joints.

I use the UL181FB tape that has the thread in it for the flex to metal joint. The mylar tape seems to me will after time get hard and then dirty and fall off.

Flex duct states that the UL tape is to be used.

I agree that the mastic paste and silicone are too messy.

 

Sealers

First off. As far as getting messy.I get paid quite well to get messy.If you pay attention to the sequence of the assembly process you can minimize how much of the stuff you take home with you in your hair.And you want to be careful of that.If you take TO MUCH it might be considerd enployee theft:} I REALLY like the foil backed mastic tape.But the cost is somewhat prohibitive.When your starting out with fifteen feet of sixteen inch round going to a couple of elbows to jockey around a support beam.Than a reducer to another ten or fifteen feet of fourteen inch round.Then a fourteen to twelve inch reducer.a couple of five footers of twelve and a plug your talking fourty one feet of the stuff just for the trunk line.Thats not including sixteen to twenty plus take offs or branch lines!!! So a little messy is what it is.A word of caution for the people out there who have not used mastic. IF you get it in your hair.DON'T let it dry.Cause when you get home and show you just might start going bald before your time:{ ....:}
41GASMAN

 

This thread is a shame! You people should know better. LEAVE this job to a PROFESSIONAL duct sealer also called a lagger. Sealing and lagging is a specialty. This is not something for an HVAC technician, duct installer or homeowner to attempt themselves.

You people have already admitted that you are messy when you attempt to do this highly specialized work yourselves. You are simply not qualified for this work. You need to call a certified sealer and lagger who has taken the time to learn the trade, pass a series of exams and become certified. Besides this can be dangerous work to perform.

The national association of duct sealers and laggers have their own website where they post photos of what they call the "Wall Of Shame". It is full of photos of sealing jobs that were done by non-professional heating and cooling people who thought they could do it themselves. (DIYers, they call us)

The sealers and laggers post day and night on their site and they make fun of us all the time. They are making us look like fools. Please stop and call a pro and get the job done right!

Norm

 

woohoo! find me one close to where I live

hoowee, no more pookying for me!

 

Care to post that website??

Apparently Google cant find it.

 

Care to post that website??

Apparently Google cant find it.

Please don't tell me you think I am being serious! I am poking fun at those of us who continually inform homeowners that they need to call a pro for every little thing they attempt to do for themselves related to our industry. As if there are no DIYers capable of performing at least some HVAC work for themselves.

 

 

Well....thanks alot Norm! I took you seriously and got a bunch of lag bolts and bolted every duct joint so I could be professional. Do you have any idea how much time that took?????

Now I find you are joking!