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Creative Ways to Vent Radon

Post in 'The Green Room' started by velvetfoot, Jul 10, 2006.

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  1. velvetfoot

    velvetfoot Minister of Fire

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    I am trying to think of a way of installing a stealthy sub-slab radon venting system. The pipe chase on my house appears to have room for another vent pipe (I have oil and wood stove chimneys in there now). Could I run a plastic pipe in that chase? If it doesn't get any closer than the wood in there, shouldn't it be safe, or would I have to use a metal pipe (the air is said to be humid, esp. in winter, so I'm not sure if rusting would be a concern). Would I need a metal vent above the chase's top? It seems like a good way to go because since it is enclosed all the way the humid air may not condense and freeze like it can do on an ugly outside installation. I really don't want to do a roof penetration on the metal roof, and also routing through the interior would be a problem. There is also a possibility that the passive approach will work and I won't have to add a fan.

    Thanks for any ideas. I'm getting more pressure to do something about this, although the numbers don't concern me that much (currently 2.3 upstairs and ~6 downstairs (with window closed and dehumidifier running)), but I think it got up to 12 at one point in the basement. Interestingly, I believe the furnace operation in winter sucks some of the zoomies out through the stack.

    Note: Since I have the radon monitors I will be putting the fan in the basement where it can easily be accessed. I understand that EPA has written they prefer a system where the piping inside the house under vacuum in case of links, but that was before these new-fangled detectors. In EPA's guidelines it seems the only place they like to have the fan is in the attic (noise, accessability) or outside (ugly, maintenance, freeze ups).

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  2. Sandor

    Sandor Minister of Fire

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    How is you basement sealed up?

    Are the expansion joints by the walls caulked? Are the walls waterproofed? Are any penatrations sealed tightly? (well, hvac, sewer) Floor painted with epoxy paint?
  3. saichele

    saichele Minister of Fire

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    Seems like ypou might have more success with the heavier grade flex pipe for ductwork. It's metal, Aluminum I think. Non combustible, corrosion resistant, and somewhat flexible.

    Stick a 4" cap at the top to fht chase and drop in some sections of dryer vent. Fit a 'pusher' fan at the bottom, and run a line subslab.

    Of course, Sandor's right - start by blocking passages into the basement - cracks, any exposed earth (crawlspace), sump, and so on. In fact, if you have a sump with subslab drainage, it's the perfect collection network.

    Steve
  4. velvetfoot

    velvetfoot Minister of Fire

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    Sandor,

    The basement is a 3-year old poured full-height basement. There are some cracks in the walls, but not too many in the floor. There is no sump pit and there is a small joint around the perimeter of the floor. I plan on caulking the floor and wall cracks and the perimeter joint. I am somewhat ambivalent about coating the walls and floors. Those coatings are stinky (unhealthy to apply?) and not cheap and the EPA's stance is that they aren't reliable and the results not long-lasting because the vapor pressure will find the smallest opening and the coating will be defeated. They do want you to caulk the cracks and joints though. On the other hand, the coatings could increase the efficiency of an active system.

    There is a substance marketed on the web call RadonSeal, but I have not been able to find anything objective about it.
  5. velvetfoot

    velvetfoot Minister of Fire

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    Steve,

    I can't say I'm familiar with the method or materials you propose. The usual pipe used is 3 or 4 inch pvc, or sometimes rain gutter downspout for aesthetics. I don't think I've ever seen this flexible aluminum pipe you're talking about. A concern is internal pipe fluid friction so that the fan can move the air efficiently.
  6. saichele

    saichele Minister of Fire

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    We had one in our old house out of PVC, looked like the electric service conduit. Actually ran right up beside said conduit. And it filled with condensation every winter. Had to shut off the fan for a fw seconds every week or so and let it drain. Probably if the pitch had been rght back to the sump it wouldn;t have been an issue.

    The dryer vent is a semi-rigid corrugated stuff. Like flexible chimney but much lighter grade (but higher than the foil stuff). Available at Home Cheapo, Lowes, etc., as well as Ace and True Valu.

    You don;t need to generate a lot of vacuum, just more than your house generates. Punch a hole in the slab, excavate a bit of soil by hand to create a well space, run the duct inthere and seal it off with a poly carbonate panel and silicone caulk. Then one of those in-duct vent fans, and the venting right up to the roof. I'd probably stick a 'clean out' in somewhere between the stack and the fan to catch any condensate.

    Note that venting the basement itself is a loser. What's driving this is the slight negative pressure generated by HWH, furnace, and the natural 'chimney effect' of the house. Unless you can somehow create positive pressure with the venting, you're probably just making it worse.

    The subslab is an interceptor - it just grabs the radon before it gets into the living space.

    Steve
  7. velvetfoot

    velvetfoot Minister of Fire

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    Thanks Steve.

    There already is a 3" pvc conduit stub punched through the slab for radon mitigation, as per the previous owner. It is located near the boiler, and as such, probably isn't in an ideal location for running the pipe or for possibly generating additional vacuum near the boiler air intake (which I am thinking of changing to outside air). My experience thus far this summer is that humid air is sucked into the basement and condenses on cool things, which lowered the values downstairs to below 4 but also increased it somewhat upstairs.

    I theorize that under slab venting will work, but I want to come up with a aesthetic, stealthy solution. I am keeping open the coating option, but as I said, the results might not be totally successful, it will be really stinky to apply, and I imagine surprisingly expensive.

    I figure I can put a timer on the fan and monitor the numbers.
  8. velvetfoot

    velvetfoot Minister of Fire

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  9. Turner-n-Burner

    Turner-n-Burner New Member

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    I had just written a long post about radonseal, but the forum software ate it.

    Short version. I was skeptical, but tried it anyway. it went down easily, and seemed to work well. my basement was noticiable drier than before, but I did get some dampness this past May just as the rivers in the area crested. My immediate neighbors both had several inches of water that they were continually pumping. I don't even have pumps.

    I haven't retested my radon yet. I'll try and do that soon and post the results. I'm thinking of doing another application just to seal the floor against another 100 year flood.

    -Dan
  10. velvetfoot

    velvetfoot Minister of Fire

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    Thanks Turner. Did you need a respirator to apply it?
  11. Turner-n-Burner

    Turner-n-Burner New Member

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    No - no respirator. just a clean basement, and a couple of pump sprayers. One for water, one for the product. It does help to have someone help you. One to spray the water, the other to spray the product.

    -Dan
  12. velvetfoot

    velvetfoot Minister of Fire

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    Well, I just may have succeeded with a temporary setup. I got the lowest power Fantech unit I could, 14 watts (yes, I am still miffed about running a kW-guzzling dehumidifier in the summer :-} . I just got my first reading - the electronic radon meter takes 48 hours for the first reading, and gives you long term, which is average to date, and short term, which is the last seven days. It was 1.6, down from about 9. The first floor is down to .3. This might go up a bit in the next few days - who knows, but I hope the basement will stay below 4 and that the first floor stays low to keep the Mrs. happy. This is with the radon fan mounted on a rubber coupling to the 4" (not 3") stub up, which was just a pipe to the gravel below with no pit or anything and pushed through flexible, corregated black plastic drain pipe to an exit through a board placed in the basement window. All joints and the window/board interface were duct taped. I have not mounted the vacuum gauge I bought - I will do that next.

    I noticed that the draft regulator damper on the oil burner vent pipe did not move - unlike in the winter when the 'stack effect' is more prevalent. I took this as a good sign that there is not that much vacuum being imparted to the basement space as a result of the radon fan, even though I have not caulked any cracks yet. Perhaps an outside air supply to the burner won't really be needed (but I still may do it, lol).

    There is a link to my temporary installation below. Remember, it took very little time to do and is just a proof of concept kind of thing. I still need to creatively vent it, but I may not get more creative than the basement window, lol.

    PS: As I said in another thread, the system is very quiet. The fan is very quiet and I think the large 4" pipe contributes to the quiet with low air flow.

    PPS: That pipe on the bottom of the first picture is just an extra and is not connected to anything.

    http://velvetfoot.com/coppermine/thumbnails.php?album=7
  13. saichele

    saichele Minister of Fire

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    1) good system, cheap and (apparently) effective.

    but

    2) Someone (such as the next buyer's inspector) is likely to cry foul. There are specific requirements as to wher it can be discharged, relative to windows and roof, and there are a bunch of marking requirements. Mine had the Danger Radioactive stickers all over it. Don;t know how big a concern that is to you. If you're planning to die in this house, this might postpone it a bit...

    Steve
  14. velvetfoot

    velvetfoot Minister of Fire

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    As I said, I have an electronic monitor in the basement and first floor. If something goes awry, hopefully I will get warned. If the next owner does not like my system he can install his own. I plan on using 4" schedule 40 pvc but don't currently plan on having it run up the side of the house.
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