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Darrell Sutherland Posted: Mar 31, 2008 05:36 AM	spraying in a conduit I have a wood doctor outside furnace and think I am loseing heat under ground has anyone sprayed inside a conduit and how far will it go in, or is there a way of extending the nozzle, I am trying to avoid digging up pipes, they are in a syrofoam box wrapped in plastic now any comments would be great thanks Darrell
mason Posted: Mar 31, 2008 08:45 AM	Lotsa concerns in the application you describe. I am not sure what you mean by conduit. I am familiar with electric conduits used to encase wiring. You would not want to install SPF inside those conduits. If you are talking about installing foam to a box that contain the conduits, here are some things to consider; 1. SPF should not be installed in too great a thickness. The exothermic heat will build up and cause the foam's physical properties to be compromised, (splitting, cracking, charring of the foam, in extreme cases catch on fire. Pour in place systems can be used for insulating large voids, but the foam stays liquid for longer periods of time, (cream time 20-60 seconds, rise time 2 to 6 minutes, depending on the formula) 2. What is in the conduit? Any electric connections? While the wiring should be OK with a pour foam, electric junctions may short with the liquid foam. 3. How hot is the conduit? Foam cannot take substrate heats greater than 200 degrees F. 4. While a pour in place foam can effectively travel long distances if the conduit is sloped, if it is horizontal or sloping the wrong way, the foam may not fill it leaving significant voids. Also if stuff is in the conduit, it may prevent the liquid foam from getting to the end and again leave voids. Without more details, I would advise against it.
Circle-D Posted: Mar 31, 2008 02:19 PM	Hi Darrell, Are your pex water lines in conduit? When I installed my Central Boiler outdoor wood furnace I just put the pex tubing directly in the ground. I then held them up as closed cell foam was shot in underneath them, around them and over them. They ended up being in the center of a ball of foam about 12" in diameter. When I piped the pex into my existing oil boiler I installed temperature gauges to monitor heat loss from the outdoor unit to the oil unit. Upon firing the new unit and watching the guages I discover there was 0 heat loss in 160' of underground pex. I surely thought this was false and replaced the guage I had installed in the system. To this day the guage in the cellar never varies from the guage on the outdoor boiler. If I were you,I'd spend the time to dig them up and foam around them. Just my 2 cents as they say.
Darrell Sutherland Posted: Mar 31, 2008 05:02 PM	Thanks guys for your response, The pex or in this case whisbro same thing for most part are in the 4 inch sdr conduit no electrical, I maybe looking at digging them up in which case I could fill the box of styrofoam with spray foam, just was looking to see if there was a product that could be sprayed in thanks again Darrell
Circle-D Posted: Mar 31, 2008 05:21 PM	If both your supply and return are in the same conduit your getting heat transfer(loss) from one to the other where they touch.You'd get a better job if you could insulate them seperately, which would mean draining and removing them from the conduit.....lots of extra work.

Author

Comments

Darrell Sutherland

Posted: Mar 31, 2008 05:36 AM

spraying in a conduit

I have a wood doctor outside furnace and think I am loseing heat under ground has anyone sprayed inside a conduit and how far will it go in, or is there a way of extending the nozzle, I am trying to avoid digging up pipes, they are in a syrofoam box wrapped in plastic now any comments would be great
thanks
Darrell

mason

Posted: Mar 31, 2008 08:45 AM

Lotsa concerns in the application you describe.
I am not sure what you mean by conduit. I am familiar with electric conduits used to encase wiring. You would not want to install SPF inside those conduits. If you are talking about installing foam to a box that contain the conduits, here are some things to consider;

1. SPF should not be installed in too great a thickness. The exothermic heat will build up and cause the foam's physical properties to be compromised, (splitting, cracking, charring of the foam, in extreme cases catch on fire.
Pour in place systems can be used for insulating large voids, but the foam stays liquid for longer periods of time, (cream time 20-60 seconds, rise time 2 to 6 minutes, depending on the formula)

2. What is in the conduit? Any electric connections? While the wiring should be OK with a pour foam, electric junctions may short with the liquid foam.

3. How hot is the conduit? Foam cannot take substrate heats greater than 200 degrees F.

4. While a pour in place foam can effectively travel long distances if the conduit is sloped, if it is horizontal or sloping the wrong way, the foam may not fill it leaving significant voids. Also if stuff is in the conduit, it may prevent the liquid foam from getting to the end and again leave voids.

Without more details, I would advise against it.

Circle-D

Posted: Mar 31, 2008 02:19 PM

Hi Darrell,
Are your pex water lines in conduit? When I installed my Central Boiler outdoor wood furnace I just put the pex tubing directly in the ground. I then held them up as closed cell foam was shot in underneath them, around them and over them. They ended up being in the center of a ball of foam about 12" in diameter.
When I piped the pex into my existing oil boiler I installed temperature gauges to monitor heat loss from the outdoor unit to the oil unit.
Upon firing the new unit and watching the guages I discover there was 0 heat loss in 160' of underground pex. I surely thought this was false and replaced the guage I had installed in the system. To this day the guage in the cellar never varies from the guage on the outdoor boiler.
If I were you,I'd spend the time to dig them up and foam around them. Just my 2 cents as they say.

Darrell Sutherland

Posted: Mar 31, 2008 05:02 PM

Thanks guys for your response, The pex or in this case whisbro same thing for most part are in the 4 inch sdr conduit no electrical, I maybe looking at digging them up in which case I could fill the box of styrofoam with spray foam, just was looking to see if there was a product that could be sprayed in
thanks again
Darrell

Circle-D

Posted: Mar 31, 2008 05:21 PM

If both your supply and return are in the same conduit your getting heat transfer(loss) from one to the other where they touch.You'd get a better job if you could insulate them seperately, which would mean draining and removing them from the conduit.....lots of extra work.

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