quote:

Originally posted by Mikito:
Seriously. Take a look at trap primers. Keeping the trap full of water is what they are designed to do.
I am sure you can retrofit without having to remove old floor drain since you have access underneath.

Is there a type or model you recommend for this? There seem to be a number of designs. The simplest that would work would be what I would prefer.

I am not a plumber but was a construction superintendent managing commercial projects.

That being said I would get one of the piston type trap primers (with no rubber diaphragm) along with a P trap which has the threaded hole for the trap primer line.

The trap primer is a pressure activated valve which opens briefly whenever there is a pressure drop from another fixture being used. Thus keeping the drain trap filled with water. It needs to be mounted at a water line that sees regular use. Then run water line to the floor drain.

The only possible fly in the ointment is it looks like the trap primer valve need to be mounted 12" above the drain they are servicing.

Some thing like PPP P2-500 P-2 Primer Automatic Trap Primer Valve

And
MI-600 ABS/PVC "P-Trap" Trap Seal Primer Connectors

The "stack" is the main vertical pipe rising out of the floor. It is supposed to be vented to atmospheric pressure, preferably above the roof line, but into the garage rafters is better then nought. Above the flood rim of the sink at least. Possibly topped with an in-line vent.

If you have no vent, as soon as negative back pressure "a vacuum" forms behind draining water, the issue starts. It will suck air from the easiest source. In your case, that has been the closest fixture to the standpipe. If the floor drain was not there, air might be sucked through the standpipe or through a sink trap - the famous "my sink gurgles when the washing machine is emptying" syndrome. Typically, when a large cross section of stack experiences copious quantities of water in free fall, the stack sucks air from the stack vent ... and pushes a column of air before it, out through the curb trap vent. Just like a subway car in an underground tunnel. Same smell, for some reason.

It is sounding like, perhaps, you have four fixtures on an unvented line. If you A] pipe the floor drain to the big vertical pipe running out of the floor, the "stack", and B] if the floor drain trap is still sucked out, add a vent, the issue should go away.

The easiest way to add a vent is to add a tee between the garage sink drain at the wall and the garage sink trap. Place this tee on its back with the center connection pointed up. Pipe this opening with 1.25" minimum preferred ABS around the sink lip, at least 6" above the flood rim level of the sink. Into the rafters is better, as it will vent sewer gas. Through the roof is best. In-line as noted above is Option III.

Woodman, I am sorry to bother you with all these questions. Thank you for your kindness in taking the time to help me.

Given the ceiling of the garage is finished, there is living space above it, and the roof is a tile roof, Option III with an in line (pop up?) vent seems the most realistic option. The only other thing I can think to do would be to run a vent into the garage ceiling and out into the soffit. I suspect that might not work, meet code, or be good practice.

Looking further...

Another trap primer type is just a line going from a sink p trap to the floor drain trap. Probably cheaper but you would have to be a able to run a line that can gravity flow between the two fixtures.

quote:

Originally posted by Mikito:
Looking further...

Another trap primer type is just a line going from a sink p trap to the floor drain trap. Probably cheaper but you would have to be a able to run a line that can gravity flow between the two fixtures.

Mikito, thank you, for posting these details about the p trap primer.

Not at all, D.O. - It's like a puzzle, one of the early text-based computer games, like Zork (1977). They are now called "interactive fiction computer games.

Nothing will be fixed until you (re)move the "branch off the branch" - the floor drain. The standpipe is calling for air when the laundry machine drains, and it will suck air from the closest source.

If you do a poll, and 100% of the people who look at the poll respond, I'd bet not 1/500 has an actual floor drain in their laundry room. Machines do not leak; modern hoses usually do not burst.

Nothing beats braided stainless steel hoses for washer washer lines. What's in the basement? What if the floor drain simply emptied onto the floor below, in the unlikely event a meteorite hits the washing machine?

No problem.
My information was just addressing how to keep a seldom used trap filled with water.

Obviously listen to the actual plumbers about fixing it so it vents properly.

quote:

Originally posted by Woodman:
What if the floor drain simply emptied onto the floor below, in the unlikely event a meteorite hits the washing machine?

Given the issues they've had with this house, I would not feel comfortable saying unlikely, but trust me at this point I am sold on not having a floor drain in a laundry room.

I think I finally get what you are saying. In the absence of a properly plumbed vent to the atmosphere, the floor drain is acting as the vent, and will continue to do so the way it is plumbed.

I seriously have no problem cutting the floor drain connection on the bottom out altogether, other than it will be obvious from below during an inspection if they ever sell the house.

Since it's only an emergency drain and not used regularly maybe just cut it out from the system and plumb it to feed to the outside of the house into a drywell or just put a screen on it to keep bugs and critters out and let it drain onto the earth.

There is a small sink in the laundry room. I checked it today, and that one has a inline vent, too, but it isn't helping because it drains into a different stack. The kitchen sink and island sink both have inline vents. That's three inline vents within 20 feet of each other. I'm wondering if all the vents on the roof are for show.