Plumbing Clothes Washer Drain Hose Direct to Drain Pipe?
Shawn Barnhart
replacement of a very old laundry room sink.
Is it sane to direct-plumb the washing machine drain line into a drain pipe,
with the appropriate trap and a check valve? Presume that I use a check
valve and a trap to prevent backflow into the washing machine.
I can't see why it wouldn't be sane -- there's no reason that the drain
needs to hang off on the sink like Grandma used to do, especially
considering that even our old washing machine doesn't have that creepy
suds-saver setting that Grandma's used to.
Speedy Jim
No, you can't simply connect a trap to any drain pipe. There are
serious issues of venting that need to be considered. Without that,
the new trap could self-siphon or other traps (sink, e.g.)
downstream could be sucked dry by the flow from the washer.
If you're removing a laundry tray, how about connecting the
washer drain hose into the now-vacant drain? The washer should
discharge into a vertical 2" standpipe (open at the top) and no
check valve is needed.
Jim
Shawn Barnhart
"Speedy Jim" <vo...@nls.net> wrote in message news:3CCDCC...@nls.net...
> No, you can't simply connect a trap to any drain pipe. There are
> serious issues of venting that need to be considered. Without that,
> the new trap could self-siphon or other traps (sink, e.g.)
> downstream could be sucked dry by the flow from the washer.
>
> If you're removing a laundry tray, how about connecting the
> washer drain hose into the now-vacant drain? The washer should
> discharge into a vertical 2" standpipe (open at the top) and no
> check valve is needed.
The drain was going to be re-used with a new single-bowl stainless
kitchen-type sink mounted in a cabinet that would provide some much-needed
storage space. Direct-plumbing the washer would save a lot of wear on the
sink.
From my almost-scientific observation of the volume and pressure of the
washing machine discharge, I can't see a vertical open pipe draining fast
enough. And what about sewer gas? Wouldn't an open standpipe let that in?
The drain pipe used before for this application is a 1 1/2" pipe which
appears to go to the roof.
My choices seem to be:
1) Connect washer to sink drain upstream from sink trap. Need 2
checkvalves -- one to keep washer water out of sink, one to keep sink from
backflowing into washer? This would seem to work to me. Trap would keep
out gas, check valves would make sure water when the right places.
2) Connect downstream from sink trap?? Sewer gas in the washer?
Speedy Jim
I wasn't clear enough. The standpipe still needs a trap where it
joins the drain. Washers do produce quite a large flow and you
have to be careful how it is tied in. I don't know what your
1 1/2" pipe to the roof is, but probably a vent for some fixture
(the sink?). Connecting a washer discharge into this pipe
*may* cause problems for the fixture trap downstream. Can't tell from
here. These are tricky issues and there are a lot of considerations
which are hard to describe in text. You might want to look into
some DIY plumbing books.
Jim
Shawn Barnhart
"Speedy Jim" <vo...@nls.net> wrote in message news:3CCE05...@nls.net...
> Shawn Barnhart wrote:
> I wasn't clear enough. The standpipe still needs a trap where it
> joins the drain. Washers do produce quite a large flow and you
> have to be careful how it is tied in. I don't know what your
> 1 1/2" pipe to the roof is, but probably a vent for some fixture
> (the sink?). Connecting a washer discharge into this pipe
> *may* cause problems for the fixture trap downstream.
It is a vent pipe. Since this is a basement, its possible I could connect
the washing machine so that nothing else is downstream. The 1.5" drain pipe
drops into the concrete basement floor about 1 foot below the place where
the old sink connected. Nothing is connected after that.
You're right in that I need to more about this, problem is plumbing is like
voodoo compared to wiring, at least to me.
D Thompson
>Is it sane to direct-plumb the washing machine drain line into a drain pipe,
>with the appropriate trap and a check valve? Presume that I use a check
>valve and a trap to prevent backflow into the washing machine.
>
What you need is called a washing machine outlet box. Standard equipment in
homes today. The outlet box provides hot/cold water shutoff valves, and an open
outlet for the discharge hose to plug into. This leaves a proper air gap that
prevents backflow and syphoning of the washing machine. They are very
inexpensive at any home center. Better ones have one-throw valves that shut off
the hot and cold water with one handle. The whole thing is designed to be
recessed into a standard stud wall if you want to finish the area.
DT
Shawn Barnhart
"D Thompson" <dth...@coreNOSPAM.com> wrote in message
news:aamds9$o0m$1...@sulawesi-fi.lerc.nasa.gov...
I did more investigating and from what I've figured out the way to do this
is a 36-48" standpipe, minimum of 2", with a trap at the bottom. Apparently
the magic is making sure that your standpipe connects to a pipe of equal or
greater size.
It was suggested that even with a 2" drain pipe I might want to consider a
3" standpipe for extra overflow protection. A 48" pipe with a 3" diamter is
only 1.4 gallons.
The bummer for me is that while the connection in the concrete floor is 2",
the drain pipe is only 1.5", which is going to require some cutting and
replacement to make this work.
Kpiog
> is a 36-48" standpipe, minimum of 2", with a trap at the bottom.
Apparently
> the magic is making sure that your standpipe connects to a pipe of equal
or
> greater size.
>
> It was suggested that even with a 2" drain pipe I might want to consider a
> 3" standpipe for extra overflow protection. A 48" pipe with a 3" diamter
is
> only 1.4 gallons.
Better check with your local building inspector for the right answer... I've
never heard of anyone using a 3" pipe for a washing machine. Our area
requires a minimum of 1 1/2" which is what most people use around here.