Radon mitigation discharge pipe

[George]

Our radon outlet pipe ends in a down-facing elbow, above the 2nd story roof. When I installed it, I put a screen over the outlet, thinking to prevent bugs and birds from nesting. In recent bad weather, the screen got plugged with snow, stopping the discharge. I pulled the screen off. Now, I'm wondering whether a screen is necessary. The airflow is fairly strong, and cool in the summer, which I think would discourage bugs. Birds, ... who knows?

If anyone has experience in these matters, I'd appreciate hearing.

Thanks, George

[Jim Elbrecht]

No experience with radon mitigation pipes-- but I know Mr. Murphy and his law all too well.

Sure as heck, as soon as that screen comes off, the fan dies and critters start lining up to get into your basement.

I would use 1/4" hardware cloth as a fair compromise between critters I could handle in the basement and allowing a free flow of air.

I just had a thought-- how did snow block it? Presumably there is a fan blowing air that is likely at *least* 25 degrees above freezing. Am I mistaken in thinking that those radon fans blow continuously? If your basement is colder than that- you might want to address *that* problem.

Jim

[Tomsic]

I left the screen off of a dryer vent one time and a few weeks later the flapper that should have closed to keep the air from backflowing into the dryer didn't close. I stuck my hand up and into the vent to see what was blocking the flapper and promptly got stung for my trouble. Wasps had moved in and weren't happy with the invasion. Lesson learned.

Tomsic

[CRNG]

On Mon, 28 Jan 2013 06:58:04 -0500, George wrote in Re Radon mitigation discharge pipe:

How about installing the screen a couple of inches up into the elbow? That should protect it from snow.

[trader4]

I don't know about the radon vent, but I found it very curious that the install manual for my Rheem condensing furnace says that you can't put ANYTHING over the

2" vent pipes that extend outside. Apparently the concern is the effect George described, ie snow/ice freezing up over any screening. The obvious downside is that there is a free and open route into either the exhaust or intake. The latter would allow a rodent into the unit compartment with the wiring, gas valve, etc. It would seem to me the risk of something bad happening, including blocking the vents without some kind of screen, is at least as great as the snow problem.

[Jim Elbrecht]

-snip-

With the furnace it makes sense, as that is an intermittent airflow [and very moist airflow, to boot] . But am I behind the times thinking a radon vent runs 24/7?

Jim

[Stormin Mormon]

Years ago, I got a call to a house with no heat. The problem turned out to be that mice had come in the exhaust vent tube. They got into the furnace compartment, unable to escape. They turned thier attention to chewing wires, and that stopped the furnace from running. The dead mouse smell was overpowering. Really awful.

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I found it very curious that the install manual for my Rheem condensing furnace says that you can't put ANYTHING over the

2" vent pipes that extend outside. Apparently the concern is the effect George described, ie snow/ice freezing up over any screening. The obvious downside is that there is a free and open route into either the exhaust or intake. The latter would allow a rodent into the unit compartment with the wiring, gas valve, etc. It would seem to me the risk of something bad happening, including blocking the vents without some kind of screen, is at least as great as the snow problem.

[krw]

They don't take air from your basement, rather from under the slab. If a critter were to crawl down one, they wouldn't end up in the basement (see: sentence #1). There isn't a lot of air coming out of these (see: sentence #1).

[hrhofmann]

But there is always some leakage from the basement into the radon exhaust system, and that means there is some place some small size critters could get into the house proper.

[homeowner]

Just a thought. Add a reducer (expander) to expand the end of pipe to 4", put screen over that. Glue the pvc part on to pipe, or just add a sheet metal screw or two. Use a coarse screen. That way you got more surface area. I'm guessing you now have a 1.5 inch pvc pipe. I dont know anything about radon piping.

1/4" hardware cloth will keep birds out, but not bugs. Better than nothing I guess..... A 1/8" screen would be ideal, if they make such a thing.

The expanded pipe should shed snow better too.

[krw]

There shouldn't be any such leakage. Nope, not if it's installed by anyone with more than a single-digit IQ. The pipe should be completely sealed from above the roof to below the slab. The system won't work if there are leaks. The whole idea is to pull a partial vacuum under the slab.

[krw]

You're right but there isn't much air flow. The idea is to pull a vacuum under the slab so any radon under the slab will be pulled out. I'm not sure there would ever be enough moisture to cause a problem, though.

[hrhofmann]

If the OP has a fairly strong air flow as stated, I would bet my pension there are some leaks somewhere. Radon just doesn't come out of the ground that readily. The vacuum sucks air into the system from all the cracks around the basement floor and walls, bringing any radon oozing thru the dirt along with it. If there were no leaks in the foundation anywhere, there would be no way for the radon to get into the basement, it would just flow around the foundation and work its way into the atmosphere all around the sides of the basement, and the OP wouldn't need an abatement system.

[gregz]

I always loose OP. I don't understand how it could plug. Warmer air. I was going to screen mine since my radon level is low in summer and fan turned off. Of course, my pipe goes up inside the house as I installed it. Don't know how OP is placed. I only used 1.5 inch pipe, works fine.

Greg

[George]

Aggregated reply:

- The screen was window screen, so quite fine pitch. And, the pipe is

3".

- After more thought, it might not have been snow plugging it. It's been cold (for here), down to 0F at night. It might be that the moist air from the sump just froze on the screen.

- IMO, it's impossible that anything could get into the basement. But, if a (stupid) bird got over the elbow, and then fell down the riser to the fan, ... yuck.

- I could put coarser screen over it, to keep birds out. But, I'm concerned that might just make it more appealing to (say) yellow jackets. double yuck.

Alas, George

[gregz]

Strong flow might mean anything. Radon leaks through cement, even if there are no visible cracks. The amount of airflow is also dependent on how much free area there is around intake. A large pit of large rocks can pull a bunch of air. If soil is water saturated, flow will decrease.

Greg

[krw]

Irrelevant. The statement "there is always some leakage from the basement to the radon exhaust system" is false. There had better not be, or the system won't work.

Define "that readily".

Wrong. Concrete doesn't form a hermetic seal. That's the whole problem. The solution is to get rid of it *before* it can percolate through the concrete. Give it a lower resistance path the the outside air, than through the house.

Again, there should be NO WAY for an animal to get down the pipe, thought the pump, into the basement. The thing would have to be broken off.

Have you ever actually seen these things?

[homeowner]

I tend to agree it was frozen moisture. Snow could not get on the underside too easily. 1/4" hardware cloth is all I can suggest. In summer, add fine screen, and take it off in winter....

[Stormin Mormon]

You realize that require climbing to the roof twice a year?

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I tend to agree it was frozen moisture. Snow could not get on the underside too easily. 1/4" hardware cloth is all I can suggest. In summer, add fine screen, and take it off in winter....

[homeowner]

The rain gutters need to be cleaned anyhow.....

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