April 26, 2010

            Dear Ken:  Our shower drain seems to ALWAYS smell like sewer gas.  Is it something that can be fixed easily, like maybe a clogged drain?    Kathy

            Your diagnosis is right on.  Showers that the two of you use seven days a week almost always fill up with strands of hair and soap scum.  Eventually that material can siphon the water out of the trap, letting in gas from the city sewer main.   You need to clean that drain out with a strong chemical.  I like plumber's acid.  It's a strong form of sulfuric that will eat its way through that clog.  There is a brand called Liquid Lightning that's available at some Wal Marts and Home depots;  Ace Hardware has their own version.  You dump in the recommended amount, cover the drain with an old plastic storage bowl and wait the recommended time.  After that, you flush the pipes with cold water for about five minutes.  Works great, but only for plastic pipes.  If you have galvanized steel, cast iron or lead drains, or are on a septic tank, use an appropriate so-called bio-active or eco-friendly product instead.  They take more material and take a little longer, but seem to work OK.    

            Dear Ken:   We have lived in our tri-level for 10 years.  Since day one, there's been a musty odor in the family room.  We have covered the crawl space in plastic-what else can we do?    Milt

            Just because you covered the crawl space with plastic sheeting doesn't mean that it's perfectly dry.  There's always a little moisture working its way to the surface.  When it hits the plastic, it condenses;  that's why the underside of the sheet always seems a little cool to the touch as well as slightly damp.   Also, that same moisture can be infiltrating up through your carpet and pad on its way to ultimate evaporation into invisible vapor.

            The cure for this is almost always additional ventilation.  Hang a box or desk fan in front of one of your crawl space vents-blowing out-and run it 24/7 for a few days.   Keep the crawl space door open for this test, so drier room air will be pulled through and exhausted outdoors.  I'll bet the musty odor will diminish after awhile.   Then you can buy a timer, plug the fan into it and set it to run for a few hours each morning.  It will also help to cut a hole in the crawl space door and cover it with a screen. 

            One caveat:  Make sure that the furnace and water heater get their combustion air from anywhere BUT the crawl space.  Otherwise, you may starve them for air-which can let fumes into the house.  Of course, you have a working carbon monoxide detector, don't you?

            Dear Ken:  Should you have the ducts cleaned in a 30 year old house?  Lucille

            It depends how dirty they are.  Use a little swivel mirror and a strong flashlight (after dark) and you can see for your self.  If there is a  layer of dusty crud, it may help to clean them.   Ask for a recommendation from your furnace guy.  The EPA doesn't necessarily recommend this, because there is no evidence that duct cleaning improves health.  Here's a great web site to check out:  http://www.epa.gov/iaq/pubs/airduct.html.

            Remember that there's no substitute for changing your furnace filter monthly.  Use the accordion style, not the cheap fiberglass kind.

            Dear Ken:   I recently updated my sprinkler system to electric valves,  I put them in one of those green plastic boxes with soil around it.  Can I stuff bats of fiberglass inside the box this fall.  Will it attract critters?    Vic

            I wouldn't do it.  You're right:  Mice or other small creatures will invade the box and set up housekeeping.  The box and its cover are enough protection.  After you turn off the water supply, cycle the clock through all the valves for a few seconds each so the water will drain away from the box.

            The most vulnerable part of the system is that copper or PVC pipe manifold hanging on the outside of your house.  You can insulate them if you want, but it won't help much.  That's because there is no heat source impinging on the manifold, so eventually the insulation and the pipes reach the same cold temperatures over night.  On the other hand, if you build a box around them touching the house, a small amount of conducted heat will flow into that space, adding a layer of additional protection from freezing.   But you must drain the system anyway, because the wind will eventually freeze the pipes no matter what.