Condensation in DC lines

Jim DeLaney

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[size=+1]Anybody else encounter this problem?

My dust collector sits in the far corner of the shop, with the lines (all 4" PVC) running up into the unheated attic, and across the trusses to ceiling drops for the bandsaw, router table, planer, etc.

Well, it's been a bit cold here lately - nothing drastic, just in the 20's. Yesterday, I started to run the router table, and could hear a funny noise in the flex hose drop. When I disconnected it, about a quart of water - and gummy chips and dust - poured out of it. Apparently, the cold air has caused that much condensation in the lines, and the droop loop in that flex line was the low point in the system, which collected it all.

Gummy mess in the line, and of course, reduced efficiency in the collection. I'm also a bit concerned that sucking that much moisture and wet sawdust into the DC may lead to mold and mildew in the collector bag.

Right now, the drops are disconnected, to drain and dry. Ayybody else got this problem. Any suggestions for mitigating it, other than bringing the lines back down into the heated portion of the shop?[/size]
 
Wow Jim, it never occurred to me that that might happen. In hindsight it makes perfect sense. Are the attic pipes accessible enough to wrap them in insulation? Maybe parting the ceiling insulation beneath them to allow them to warm enough to not cause condensation?

Just my simplistic view - Fortunately there are greater minds hereabouts and someone will have a great answer.
 
[size=+1]Rennie,
I don't think parting the insulation under the ducting would be practical, since I'd lose a lot of heat from the shop that way.

As for wrapping them, I'd essentially have to re-plumb - remove the piping, maybe ad a bit of height for clearance, and then wrap it. Also, wrapping it would make it much more difficult to open it up if a clog occurs.

I may try just laying some insulation bats on top of it, but I doubt that will be very effective.[/size]
 
jim, the simple solution is to process more lumber;) ....the sawdust will keep your lines dry and polished on the inside if you run enough through em......
 
After I wrote that I should have gone back and done an edit - what I was thinking and what I was writing did not say all together the same thing.

When I was thinking "split the insulation" below the pipe I was visualizing cutting it and pulling it back a few inches to either side to expose the pipe to the warm ceiling below. Then you would "tent" new bats over the pipe and a foot or so to either side (clear as mud?).

This should keep your pipes warm enough to control the condensation without sacrificing heat from the shop.
 
Jim, the only thing that comes to mind is adding insulation over them. This can be done by either rolls or blow in. This would also help keep the shop warmer. Hope this helps.
 
[size=+1]
Also, wrapping it would make it much more difficult to open it up if a clog occurs.

size]

Jim, you don't have to take the lines apart to free up a clog, if you will get a (Non Powered) plumbers snake like one I have that is about 40' long, (IIRC) and the same size diameter as the powered ones, (about 1/2") and it has a slip handle that you slip over it and fasten a thumb screw to turn it. Just turn on the DC, and then go to the opposite side of the clog and insert the snake through one of the tool connections and feed it in and twist it. When you bore through the clog, the airflow will suck it on into the DC. Be sure to put a tape around it to mark it at a length less than the distance from where you are putting it into the duct and the DC, so you don't run it in too far and get it into the impeller.
 
Simple solution is not to run the DC in cold weather but obviously that is the lesser solution than you are looking for. My suggestion is to put a trap (double ogee curve) in the line to collect the condensation. Then put a simple oneway valve in the bottom of the trap so allow to drain off the condensation. My guess is that while running the DC moves the air too quickly for condensation to form but the instant it shuts down the warm moist air that has been drawn in, starts the condensation. With the trap, the water would be collected and allowed to drain (similar to the condensation drain in you home AC unit. It would require that the piping be pitched toward the trap, etc. but I think it would be simple solution.

Worse case after that might be the collection of dust adhereing to the moist walls of the piping.

Although the piping into the attic cleared the clutter from your shop, it created this problem. "Best laid plans of mice & me.... " :huh: Seemed like a good idea at the time.

The one way valve could be a hole in the bottom of the trap with a rubber flap that would open for the water to drain and be sucked over the hole by the DC when it is turned on. Actually may not even need a valve as a small hole would allow drainage an might be a mimimal amount of leakage for the DC.

Another solution might be to use a series of gate valves to draw outside air into the pipes to replace the warm moist air when you shut down.
 
...the lesser solution than you are looking for. My suggestion is to put a trap (double ogee curve) in the line to collect the condensation. Then put a simple oneway valve in the bottom of the trap so allow to drain off the condensation...

[size=+1]Yeah, that might work. Worst case would be the drain hole freezing over, or the condensation being great enough to overfill the drain pan and leak onto the insulation and upper side of the drywall. Four 90° elbows ought to do it (eight, actually - I have two separate lines up there). Wonder how much the elbows will restrict the airflow?[/size]
 
Jim, Why not put a T in the lines at a low point w/ the T pointed down, close off the bottom and put a valve on it, then you can just use it as a condensate drain like an air line condensate drain.

[size=+1]Yeah, that'd probably work. It's about 2° up there right now, though. Maybe on Sunday. It's supposed to get up to 34° then.[/size]
 
Jim,

Seems you're getting a lot of suggestions on how to get the water out. I still maintain it's better to keep it from ever forming in the first place. Why treat symptoms?
 
Jim,

Seems you're getting a lot of suggestions on how to get the water out. I still maintain it's better to keep it from ever forming in the first place. Why treat symptoms?

[size=+1]Rennie,
In this case, it's better to 'treat the symptoms' because the alternative would be to re-plumb, with the piping brought inside the (heated) shop, hanging in view, under the ceiling. For aesthetic reasons, I really don't want to do that if I can avoid it.[/size]
 
jim, installing drops or moisture traps will cause lots of turbulence, unless you`ve got one heck of a blower i`d look for a way to keep the moisture from forming in the first place.......either insulation, heating the lines or something? how about a small fan to keep air moving through the system when it`s cold outside? tod
 
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