QUESTION: Our garbage disposal can't drain the dishwasher discharge fast enough, so there's a momentary backup into the sink. The disposal works fine when used alone, with no backup. The plumbing downstream has been checked and the sink trap replaced. The drain lines appear to be clear. Is it possible to have a partial blockage of the disposal? If so, how is it cleaned out?
ANSWER: Sounds like you have some sort of blockage in the drain system, because the disposer has no way of holding water. To check this, disconnect the power to the disposer, then disconnect the trap.
Look into the disposer's discharge port to make sure it's clear. Then, with a bucket under the garbage disposer, pour some water through it to make sure it flows freely. Reconnect the drain trap and the electrical power.
If the garbage disposer appears to be clear, have a plumber or sewer cleaning company auger out your drain system. Be sure they use a motor-driven auger-type clean head tool and not a hand snake. A snake will puncture a hole in the obstruction but it will not actually clean the insides of the pipe as well as an auger.
Valve May Eliminate Need for Demolition
Q: We will be installing a new sink in our bathroom that, according to a plumber friend of mine, will need to be vented with a new vent line. We've both sized up the situation and agree that running the new line through the existing walls will be a very difficult job entailing major demolition and reconstruction. Is there any alternative to venting the sink?
A: You may be able to use a ventless, or anti-siphoning, valve. This valve opens automatically to admit air, which prevents water from being siphoned from the trap, then closes to block the escape of sewer gas.
The valve installs behind the trap and solvent-welds to 1 1/2-inch diameter plastic pipe. It can be joined to the same diameter metal pipe if its solvent-weld adapter is discarded. Although the valve meets national plumbing code requirements, it may not meet local standards. Check before you install it. The valve sells for about $5 at hardware stores and home centers.
Double-Pane Window Is Costly to Replace
Q: In 1990, we bought a new home with double-pane windows. I accidentally cracked the inner pane on one of the windows. This allowed moisture into the pane, causing fogging. I would like to know how to repair it. Two glass companies said it would cost several hundred dollars, but I'm skeptical. Can you help?
A: Unfortunately, there is no way to fix the pane. It must be replaced. It's not as simple as removing one of the panes, replacing it with a new pane and then sealing it with a caulk gun. Double- and triple-glazed windows have an airtight seal between the panes. This is achieved under carefully controlled conditions at a factory, where the panes are cleaned and sealed together. It's unlikely that a homeowner can duplicate this.
To submit a question, write to Popular Mechanics, Reader Service Bureau, 224 W. 57th St., New York, N.Y. 10019. The most interesting questions will be answered in a future column.