Drain pans for W/D, water heater, etc.
I got some interesting feedback on this topic at JLC and figured I would check here to see what you guys do.
As we are prepping a slab I am thinking about everything that needs to go under there. The laundry machines and water heater are on the first floor and are in tiled areas, but most of the house is bamboo flooring.
Normally I am a fan of drain pans under things that might leak. The water heater in my shop is on the second floor, above my office, and you bet it’s in a drain pan, with pipe to the exterior. The unit is in heated space and the drain pan line constitutes a small but direct air leak to the exterior.
For the current house there is of course no floor framing, so a drain line would have to run thru the slab. No problem, we could rough that in underslab and tie into it later. I was also wondering why one couldn’t simply run it thru the slab and if there’s a leak it would drain into the very large amount of gravel under the slab. Third option is to install a floor drain with a trap primer.
Anyway, the upshot seems to be that almost no one really installs drain pans. Do you put them on your jobs? If so, how do you get them out thru a slab?
Replies
I have them installed. Only thing is that in the case of a slab floor I have them run the drain out of the side of the pan and to the exterior. Granted this is not as good as a bottom drain, but I'm comfortable with it. If it is a framed floor, the drain is out the bottom of the pan, which still would let a little water set in the pan - if there were a leak - since the fittings they install to the pans have a lip on the interior of the pan. Houses I'm building now, the direct vent gas water heaters are in the garage, so no pans. The washer still gets one.
One thought regarding your idea of just running drain pan outlets under the slab into the gravel, this could give a good leak path for soil gas like radon - maybe not a concern in your area.
Plumbers have asked me why do you want a washer pan on the first floor (with no living space below)? Something I've learned the hard way.: A leak anywhere in the finished area of the house is a huge bummer...
Right, like the dishwasher or refrigerator w/icemaker in a house with wood floors.
I wonder if you couldn't route the drains to a small sump. Either equip the sump with just an alarm, or add a small sump pump. (Of course, you might be required to provide a vent for the sump, plus meet other regs about sump pumps in your area.)
If it's going to get formal, it seems easier to just tie into the rest of the fixture drains with the floor drain/trap primer setup. I have installed sewer ejectors and I suppose one of those would work, but they have been ~40 gallon size and take up some space (also vented as you say). This house barely has room for the DHW and heating.
A trap quard should work to make it a primerless trap and run in into a drain.Or you could also run it outside, where elevations allow and that TRap guard will keep out the air..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.