Trap Primer Question

[Mculik5]

Hi.

I'm renovating our second floor bathroom, which also houses our washer and dryer. One of the improvements I'd like to make is installing a floor drain to prevent catastrophe in the event the washer fails and dumps water all over the floor.

Given that the intent is that this drain won't be used, I'd like to install a trap primer to keep the trap sealed.

The joists are 2x10 (so 9" of actual depth) and the subfloor is 1 1/8". So, I've safely got about 9 1/2" of height for the install of a KERDI-DRAIN, 2"-1 1/2" reducer and trap. Plus, I need to get the trap primer line in there.

To do that, I found this - https://www.pppinc.net/products/acc...ompression/precision-priming-adapter-pvc.html

But, it adds significant height to the assembly, even if I cut it down.

What are some of the other methods for getting the trap primer line plumbed to the trap? Can you drill and tap a hole somewhere in the assembly and add a fitting? Or is the use of some kind of adapter like the one I linked to required?

Thanks.

 

[Terry]

That looks like it would glue into the p-trap and then allow the vertical from the drain into the top.

 

[Sponsor]

 

[Mculik5]

@Terry - That's exactly right. My issue is that with that part installed, the total assembly height exceeds the joist + subfloor height. The attached diagram might help clarify the situation.

So, my question is, is there an alternative method to get water into the trap from the trap primer that doesn't involve this extra piece? What is customary in the field? Does everyone use these primer adapters? Is there another method that's common? Could I just drill/tap the PVC someplace above the trap, install a fitting and connect the water line that way?

Thanks for your help!

 

[James Henry]

Google trap primer tail piece.

 

[James Henry]

You can buy a floor drain with a trap primer plug built in.

 

[Mliu]

The trap primer tailpiece pictured in the post above this one is for capturing water from the lavatory drain; it provides the prime water for the floor drain trap.

 

[Mliu]

OP, what kind of floor are you installing this floor drain into? Zurn makes a PVC floor drain with a built-in trap primer port. You just knock out the PVC plug if you want to use a primer. You can see the threaded port on the side of the blue body:

 

[Mliu]

Or, you could forget the trap primer and install one of the new trap seal devices. Like Rectorseal's SureSeal:

These are easier to maintain than trap primers (which are a big problem if they fail or if the primer line gets clogged). The rubber flapper in the trap seal helps prevent the water in the trap from evaporating, and even if it does dry out, the seal prevents sewer gas from escaping the drain.

Since it's unlikely this drain would ever be used, I'd install a trap seal AND pour some RV antifreeze into the trap. The RV antifreeze will not evaporate.

 

[Mliu]

If you're really concerned about a leak or overflow from your washing machine, I strongly suggest you install a washing machine drain pan under your washer:

This one is stainless steel so it looks really nice, but it's also more expensive. If the washer will be in a laundry closet, you could use a less attractive (and less expensive) one made of galvanized steel.

 

[James Henry]

The trap primer tailpiece pictured in the post above this one is for capturing water from the lavatory drain; it provides the prime water for the floor drain trap.

He said he wanted to install a trap primer. I was showing him an alternative. Haphazard post on my part.

 

[Mculik5]

Thanks for all the feedback.

@mliu - I'm taking your suggestion - SureSeal and antifreeze. I'm installing a 2" Kerdi-Drain. Ordered a SureSeal online and it arrived yesterday. Fits perfectly and seems like it might provide some measure of backflow prevention, too.

I'm using Ditra on the floor and Kerdi-Band on the first few inches of wall (with tile baseboard), so no need for a washer drain pain.

Thanks all for the help!

 

[Mliu]

Just be sure to use RV antifreeze, not engine (automobile) antifreeze. RV antifreeze is used for winterizing potable water lines in RVs and is non-toxic (in fact, it's food grade).