Floor Drain Primers

[xserver]

I have a floor drain in my laundry room attached to a primer. A plumber noticed that the primer had stopped working so the drain was dry. The primer was installed with the house when I bought it new 10 yrs ago.

He said these primers are worthless and only last 6 months. He said I should just remove it and not bother with it. Is this true?

[Randyj]

nope...not true.

[Gencon]

Agreed. Where is the primer being fed from, the laundry faucet?

That dry trap can allow poisonous gasses into your house, and some really stink.

[hj]

Many of them do not work from the day they are installed, but inspectors like to see them. The only ones guaranteed to work are those that the water to the faucet runs through them, not set off line screwed into a tee.

[Randyj]

All the (few) trap primers I've seen are mounted vertically on a loop as high as possible in the room/above the fixture where it serves the trap. It operates by detecting the change in water pressure. If it is mounted in an area that seldom if ever has a water pressure change (flushing a toilet or opening a faucet) then it is not going to be working often enough to keep a trap wet. I'd bet there are thousands of plumbers out there who don't have a clue how trap primers work or how to install them.... I only have a vague idea about them.

[xserver]

It's teed off the laundry faucet. I believe the water supply runs from the ceiling, then to the laundry faucet, then to the primer.

The primer looks for a pressure drop, which happens when the washer fills, right?

[Randyj]

Yep. If the water is feeding down I don't know how this would affect the physics of the water pressure. It may need to come from near the bib then go back up to the ceiling then a line back down to the trap. If the water is feeding from the top then it may not have much of a pressure drop. I would also suspect that high water pressure might negate the effect of the washing machine valve opening.

[srdenny]

Replace the primer with a new one. Cut the water line on the discharge side of the primer, unscrew the primer, disonnect the cut piecre from the old primer, flush the line real well (at least 3-4 gallons worth), install the new primer, screw on the piece from the old primer, solder a stopless coupling, turn on the water and check for leaks. The old primer was probably clogged by debris in the house lines when new. Installing a shut-off valve upstream and a union downstream of the primer is a good idea for future maintenance.

[hj]

The problem with the pressure drop operated ones is that if the line is large enough and the faucet's flow is low enough, there will not be a pressure change to operate it.

[xserver]

Thanks for all the info!

Now I've discovered that the primer ISN'T EVEN HOOKED UP to the water line! If I want it to work I have to cut the wall and tap into the water line. Argh!

[Randyj]

Don'tcha luvit when a plan comes together!

[srdenny]

Thanks for all the info!

Now I've discovered that the primer ISN'T EVEN HOOKED UP to the water line! If I want it to work I have to cut the wall and tap into the water line. Argh!

Is the primer presently hooked up to anything, or is it just capped off?

[Cass]

How about replacing the water in the trap with RV anitfreeze.

[hj]

If it is not hooked to the water line, what is it hooked to? I doubt that it is just hanging inside the wall.

[xserver]

It's just hanging there and not capped off.

[Rancher]

Hmmm I got a shower with a drain in it that is never used, we just pour a cup of water down it from time to time.

Cass, I like that idea, with the antifreeze evaporate? How about some 10W-30 shaken up in a jar of water and then quickly poured down the drain, then the water would never evaporate...

Rancher

[markts30]

I don't know about motor oil, but one guy I work with swears by linseed oil...
I would just hesitate to use anything that might react with the plastic....
I don't know enough about the chemistry of oil and plastics to know what might be safe...