Author Topic: clamping rigid ducting to dryer?  (Read 1589 times)

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Offline mrFinpgh

  • Posts: 488
clamping rigid ducting to dryer?
« on: September 05, 2021, 06:09 PM »
Had to replace the washer/dryer this month.  The old duct was flexible vinyl.  Thought it would be good to update that to rigid metal ducting.

Most of it seems to be coming together fine, but the connection between the dryer and the elbow doesn't seem to be very good. I have put a hose clamp on it and it tightens to a point where I can't turn the screw any further.  But, you can still wiggle the elbow off the crimped exhaust if you put a little effort into it.

Am I missing something? The old flex vent clamps very securely, but of course it's much more malleable than the rigid duct.  Can I foil tape the connection and call it good, or is that clamp a must-have?

Definitely out of my element in this case, so thanks to anyone who knows.

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Offline Packard

  • Posts: 623
Re: clamping rigid ducting to dryer?
« Reply #1 on: September 05, 2021, 06:56 PM »
I used a large hose clamp.  Remember do not use sheet metal screws to join the sections of pipe. The protruding ends catch the lint and create a fire hazard. Use the aluminum tape instead. The adhesive is tenacious.  It will make a stronger, safer joint.  And it is faster and easier too.

Offline Cheese

  • Posts: 8879
Re: clamping rigid ducting to dryer?
« Reply #2 on: September 05, 2021, 07:30 PM »
I’d use a sheet metal hand crimper to reduce the OD slightly, then the hose clamp will give you a nice firm connection.
If that’s not available, you could make several short cuts in the end of the rigid duct to also help reduce the OD. Just make sure the rigid duct is over the outside of the dryer stub and not on the inside.
All additional pieces of duct need to be placed on the outside of the preceding piece. Then seal with aluminum duct tape and not gray fabric duct tape. The fabric duct tape will eventually fail and fall off.

Offline Mortiser

  • Posts: 95
Re: clamping rigid ducting to dryer?
« Reply #3 on: September 05, 2021, 08:45 PM »
Or maybe try a different solution...

https://www.magvent-dryervent.com

A Fine Homebuilding (#300) article spoke highly.

----
Rich

Offline JD2720

  • Posts: 1229
Re: clamping rigid ducting to dryer?
« Reply #4 on: September 05, 2021, 09:42 PM »
You could make a cut in the elbow where it slips over the pipe on the dryer. The cut will allow the pipes to clamp together better.

I used the Magvent on our dryer & it works great.

Offline Steve1

  • Posts: 99
Re: clamping rigid ducting to dryer?
« Reply #5 on: September 08, 2021, 07:14 AM »
Yes, you can foil tape it and call it a day.

Offline Bob D.

  • Posts: 2272
Re: clamping rigid ducting to dryer?
« Reply #6 on: September 08, 2021, 08:23 AM »
Be sure the upstream fitting is fitted inside the downstream fitting/pipe.

If not then it will create a place for lint to accumulate and could lead to
a restriction or blockage.
-----
It's a table saw, do you know where your fingers are?

Offline JimH2

  • Posts: 1064
Re: clamping rigid ducting to dryer?
« Reply #7 on: September 08, 2021, 10:49 AM »
Definitely do not use screws of any type. Suitable tape works great though the MagVent looks like a winner. Of course the problem with dryer vents is always the space behind it. Never quite enough unless the stars align.

While only partially related I have used products from the Inovate Dryer Products. I have use the Dryer-Ell for long runs (save length by being a sweep instead of a straight 90) and the Dryerbox for every install since I found out about. I also use their DryerFlex hose. Their newer Wall Vent product looks very good compared to the plastic solutions currently on the market that warp. I doubt you will be disappointed with any of their products.




Offline Bob D.

  • Posts: 2272
Re: clamping rigid ducting to dryer?
« Reply #8 on: September 08, 2021, 02:00 PM »
" Of course the problem with dryer vents is always the space behind it"

My trick for dealing with this is to place a 2x6 on the floor behind the washer and dryer. This keeps anyone from pushing them back too far and crimping a hose or crushing the vent.
-----
It's a table saw, do you know where your fingers are?

Offline leakyroof

  • Posts: 2357
Re: clamping rigid ducting to dryer?
« Reply #9 on: September 09, 2021, 12:48 PM »
" Of course the problem with dryer vents is always the space behind it"

My trick for dealing with this is to place a 2x6 on the floor behind the washer and dryer. This keeps anyone from pushing them back too far and crimping a hose or crushing the vent.
  I like it... maybe write on the 2x , "This is to prevent idiots from doing something stupid"... [big grin] [big grin]
Not as many Sanders as PA Floor guy.....

Offline Packard

  • Posts: 623
Re: clamping rigid ducting to dryer?
« Reply #10 on: September 09, 2021, 03:41 PM »
The aluminum tape's adhesive is so tenacious, and the tape is so strong that I would not have a problem with a simple butt joint using that tape.  I would probably take a couple of wraps.  But it will hold.


Offline Cheese

  • Posts: 8879
Re: clamping rigid ducting to dryer?
« Reply #11 on: September 09, 2021, 06:31 PM »
The aluminum tape's adhesive is so tenacious, and the tape is so strong that I would not have a problem with a simple butt joint using that tape.  I would probably take a couple of wraps.  But it will hold.

The tenacity of the adhesive is because it's acrylic based rather then rubber based.

The strength of the tape membrane is because it's aluminum versus cloth based.

For exactly the reasons you point out, that's the reason cloth based duct tape is never recommended for HVAC applications. 
[smile]

To really get the metal duct tape to lay down smooth on the surface, I always go over the taped joint with a 3M Bondo spreader.  Burnish it really well and the stuff becomes glass smooth and will absolutely not leak.


Offline mrFinpgh

  • Posts: 488
Re: clamping rigid ducting to dryer?
« Reply #12 on: September 09, 2021, 07:54 PM »
Thanks, everyone. I've learned some new stuff about ducting now.. should be handy if I can ever get an actual shop. :-). Happily, i was able to arrange the elbows to avoid any 90 degree turns and also avoid having to cut any of the rigid duct pieces.

Putting some snips in the piece that goes over the dryer vent did the trick - the clamp tightened up much better. 

I did use tape on the joints, but it didn't look like the one you all are showing. It was listed as dryer vent installation tape - felt more like packing tape. Is this the incorrect tape for this purpose?

Offline Packard

  • Posts: 623
Re: clamping rigid ducting to dryer?
« Reply #13 on: September 10, 2021, 08:51 AM »
A few points.

1. The photo I posted was lifted off the internet.  It is not my installation.
2. My hookup was similarly very low to the floor. 
3. I had to pull the dryer from the wall to install the elbow there. I also installed two sections of straight pipe before I pushed the dryer back to the wall.  Once I had the dryer back against the wall it was one more elbow and then out the wall. 
4.  You want to install to the dryer first and install enough straight pipe to allow easy working for additional sections.
5.  Cheese and I seem to agree that the aluminum tape is first-rate.
6.  Unlike water inlet pipe, there is no pressure on the pipe.  The dryer is not likely to be moved until it is time to replace it.  So damage due to movement is unlikely.  I really have no worries about the taped joints failing.
7.  When I replaced the old  flex pipe (vinyl) there was lots of lint in the interior, probably due to the fact that the interior is not perfectly smooth.
8.  Everything I read said "no screws" and "no pop rivets" to join the pipe sections.  The protruding ends will trap bits of lint which will grow to larger mounds of lint.  So use the aluminum tape. 
9.  The  aluminum tape was easy to  find at Lowes.  It was displayed along with the ducting materials.  It feels like really thick aluminum foil. I'm pretty sure it is the same stuff that they use for solar tubes for skylights.
10.  I see that 3M makes the foil tape in 3.5 and 4.6 mil thickness.  I don't recall which I used.

Offline Sparktrician

  • Posts: 4186
Re: clamping rigid ducting to dryer?
« Reply #14 on: September 10, 2021, 03:53 PM »
A few points.

<SNIP>
7.  When I replaced the old  flex pipe (vinyl) there was lots of lint in the interior, probably due to the fact that the interior is not perfectly smooth.
</SNIP>
 

Around here, the vinyl flex pipe is a code violation.  Much better to use the corrugated aluminum pipe.   [smile]
- Willy -

  "Show us a man who never makes a mistake and we will show a man who never makes anything. 
  The capacity for occasional blundering is inseparable from the capacity to bring things to pass."

 - Herman Lincoln Wayland (1830-1898)

Offline Packard

  • Posts: 623
Re: clamping rigid ducting to dryer?
« Reply #15 on: September 10, 2021, 04:16 PM »
The vinyl flex was a residue from the previous owner of the house. I replaced it when it showed signs of old age. The aluminum flex pipe will last longer, but I think the corrugated interior will trap lint just as well.

Offline Cheese

  • Posts: 8879
Re: clamping rigid ducting to dryer?
« Reply #16 on: September 10, 2021, 05:50 PM »
The aluminum flex pipe will last longer, but I think the corrugated interior will trap lint just as well.

It will, that's the reason I go to great extremes to avoid using any of the corrugated HVAC/Venting products.

Install a new/clean run of smooth wall round duct vent, run the dryer for a year and come back & look inside...the walls will be coated with a thin layer of dryer lint. Examine it again another year later and that coating of lint will be thicker than it was the year before and it continues to grow thicker year after year.

The humidity in the exhaust air from drying the clothes will collect on the duct wall surface and will attract dust, lint, & whatever and this eventually needs to be removed with a brush. I installed smooth wall duct work throughout the entire vent system but I still have to clean mine every 3-4 years.


« Last Edit: September 10, 2021, 05:52 PM by Cheese »