dust pipe insulation

[Jim Andrew]

Keep checking the big box stores for any 6" pipe insulation. Nothing available that doesn't involve wrapping. Ideally, some of that foam slitted insulation that they make for water lines, that you just force around the pipe and it kindof just stays around the pipe. My dust piping is in the attic of my shop, wanted to use a 50 gallon drum for the dust collector, and it also lays up there supported on the ceiling joists very nicely. Just cut holes in the ceiling for the drops. But anyway, would be nice to be able to insulate the pipe and haven't found anything.

[Bob Wingard]

It's out there .. either Grainger or McMaster-Carr carry it ... BUT ... hold on to your wallet ... very $$$$$$\

Here's some ... for ONLY about $5.00/ft + shipping ...

http://www.statesupply.com/maintenance-supplies/steam-pipe-insulation/if1053x

[Larry Browning]

Why is it that you feel the need to insulate DC ducting? I would understand heating and ac ducting but dust collection? I am sure there is a good reason it just escapes me. Adn what is the problem with the wrap stuff?

[David Kumm]

Jim, my blower and piping to the filters sits in the attic. Just to make me feel better about not losing heat in the attic I wrapped regular bat insulation around the outlet pipe and sometimes just draped it over the top. The return air is fine and I've never seen any appreciable condensation when I've gone up there and looked. Dave

[Jim Andrew]

Guess it seems inefficient to have a cold dust system in winter and hot in summer. The rest of the shop is insulated, and the air from the dust system is returned to the shop. Thus bringing in cold air in winter, hot in summer. Maybe I'll buy some batts and try to put it around the pipes. Menards has some 22 1/2" on sale this week. 6" x 3.141 equals 18.84" wide. Considering the insulation would be bigger on the outside, maybe I'll just try it whole before cutting.

[Larry Browning]

So how long do you think it will take to get your investment back? Considering that the DC is run only a fraction of the time that a HVAC system is run. And think of the extra hassle insulation will cause when you decide to move the ducting when you rearrange the shop layout.

[Ron Natalie]

Where does the DC exhaust to? If it doesn't exhaust back in to the shop space you've got bigger issues than the duct being insulated.

[Jamie Buxton]

Could you make simple walls flanking your pipe -- maybe just cardboard -- and fill with blow-in insulation? That stuff is really inexpensive.

[Larry Browning]

How long are your runs? unless you have several runs the full length of the shop, I just can't see how your energy loss is going to be anything but minimal. After all we are talking about a 6" duct not a 12" HVAC duct.
If you must do this, I really like Jamie's idea of the cardboard walls filled with the blown in stuff.

[Jim Andrew]

My system exhausts the air back in the shop. When I get in front of the air, it feels like AC in winter, heat in summer. Menards has some 22 1/2" R 13 on sale, think I'll try a bag of that.

[Bob Deroeck]

Jim, I suggest you calculate the heat loss and then decide if it's worth insulating the pipe. Use an overall heat transfer coefficient of 1.5 BTU/hr ft2 degree F. This is based on PVC pipe about 1/8" thick and "still" air in the attic (no wind). Calculate the surface area of the pipe (3.14 x pipe diameter in feet x length of pipe in the attic). For "degree F" use the temperature difference between the shop air and the attic air. For "hr" use the number of hours you are running the dust collector over the winter. Heat loss = 1.5 x A x degree F x hours.

As an example, if there is 30 ft of 6" PVC pipe in the attic with an average attic temperature during the winter of 30 F, a shop temperature of 60 F, and 25 hours per week with the dust collector operating from November to the end of March (5 months x 4.3 weeks/month x 25 hrs/week = 542 hours), then:

Area= 6.25" (pipe OD)/12"/ft x 3.14 x 30 = 49 ft2.

Heat loss = 1.5 x 49 ft2 x 30 F (temperature difference) =2205 BTU/hr

542 hours/year x 2205 =1.2 million BTU/year. Depending on your location and type of fuel and heater efficiency the cost of fuel will range from about $6/million BTU for low cost natural gas to about $60/million BTU for electric heat at 20 cents/KW.

Jim, after you do your calculation you can decide if it's worth your while to insulate pipe. If you do decide to insulate the pipe and the attic is free from rain, I suggest you consider just wrapping 3.5" fiberglass batts lengthwise around the pipe and holding them in place with thin baling wire. Cheap, easy and effective.

Bob

[Chris Ambroson]

Keep in mind that unheated (room temperature air) blowing across your skin at any speed is going to feel cooler than it actually is. Actually, any air less than 98.6 degrees (considering you are a healthy human) will feel cooler. Maybe put a thermometer in the exhaust to measure the difference to the intake. My guess is that over a 30 foot run, you don't lose as much heat as you think you do.

[Bruce Wrenn]

Buy some flex heating duct. You may have to get 8" to fit over fittings in PVC. Break a joint apart, and slip flex over PVC. Reattach joint and pull flex back over fitting.

[Jim Andrew]

Have spiral metal pipe. Would have used plastic, but couldn't find a source for 2729. Assume that metal transfers the cold or heat faster than plastic.

[Larry Browning]

I don't think we are going to talk you out of doing this. Just be aware that this is not going to be cost effective, but it probably will make you feel better about it and that carries quite a bit of value.

[Bob Deroeck]

Jim, use a multiplier of 1.7 for steel pipe instead of 1.5 for PVC pipe. The primary factor affecting heat transfer in your situation is the heat transfer from the outside surface of the pipe to the still air that surrounds the pipe. The thermal resistance of the pipe wall is relatively small for either metal or PVC pipe.

Bob

[Craig Michael]

Keep checking the big box stores for any 6" pipe insulation. Nothing available that doesn't involve wrapping. Ideally, some of that foam slitted insulation that they make for water lines, that you just force around the pipe and it kindof just stays around the pipe. My dust piping is in the attic of my shop, wanted to use a 50 gallon drum for the dust collector, and it also lays up there supported on the ceiling joists very nicely. Just cut holes in the ceiling for the drops. But anyway, would be nice to be able to insulate the pipe and haven't found anything.

What you want is called is an insulation called ductwork sleeves. They are 5' round sleeves of fiberglass insulation with the plastic sleeve around the outside, foil type too (I like that MUCH better). It just slides on like a open ended sock. Here are a few links to show what it's like. HD might have it, ditto lowes. Check the price there vs. a local hvac supply house. Most of the time for anything like that the supply house will have better pricing. None of the places will be very expensive, it's just a little insulation and a cover.

http://www.slcbungalow.com/?p=52

http://www.flexmasterusa.com/LinkClick.aspx?fileticket=pnSkBEYdaE8%3d&tabid=68