Is this HD double sink drain kit from HD a good idea? Will I need a vent when it replaces the old S trap that never seemed an issue?

[JamieRI]

I have an S-trap, no cabinet floor, a new tankless RO filter, and the following goals:

1. Push the plumbing under the kitchen sink to the back wall so I can put slide out organizers, perhaps like this HD Organizer
2. Cram my new tankless RO filter in there too
3. Reduce S-Trap risk that theoretically exists
4. Meet code too!

My story: I purchased and installed a new tankless reverse-osmosis filter with remineralization filter to lessen the heavy metals and pesticide my water company reports. The floor of the cabinet was rotted so I tore it out expecting to replace it with plywood. Along with this project, I thought it would be nice to replace the wastewater plumbing with pipes routed along the back of the cabinet so that organizers can be put in for better undersink storage. I read about the S-trap risks and non-code compliance problem.

Home Depot sells This Sink Drain Kit with horizontal waste arms that looks appealing as it adapts to a variety of situations as the HD drawings show. In my case, there is a disposal, dish washer, RO filter waste tube, and a waste-water exit through the floor of the cabinet. The kit shows P trap, but I would need to put an elbow at the end to run it into the basement, through the existing hole. Since the cabinet does not have a floor at the moment, I might be able to put the trap very low so that the horizontal piece is low enough to allow me to put a plywood deck above it, along with my drawers. Problem with that is there is no vent, however the vertical run to the basement is pretty short. If I added a vent, it would need to go where I want to put the plywood deck, right?

So, is the HD rig known to be a good product?
And what sort of venting would be needed to strictly meet the plumbing code?
I show before and after ripping out the cabinet floor and installing the RO filter. I also show my basement wastwater pipe.

Thanks!
Jamie

 

[Riickk]

I can't speak to anything else, but years ago I put an RO system in - Water tap at sink, and feed to icemaker.
Before I bought it, checked with Seller, and learned I could put it in the basement (high-up), and it would still work. Ther's lots of fine detail work to put it in that cabinet, but it's easy to run 1/4" tubing up from the basement to wherever you want or need it.
.

 

[Helper Dave]

I don't like where the branch piece for the dishwasher drain is in that kit. It's too low. It should be right up by your sink like it is now. With it so low, I'd worry your trap could back up just far enough without the sink backing up, and then you could get water backing up into your dishwasher without the visual feedback of your sink not draining. Just the force from a garbage disposal could send water up that way, too. Yeah, most dishwashers these days have check valves to not allow water coming back in, but better not to test them unnecessarily, in my opinion.

You can buy the traps, the y-branch, extensions, and whatever else you might need separately for about the same money, if not cheaper; then you're getting enough flexibility to set it all up better.

Keep in mind you'll need a good 3-4" of straight pipe after the p-trap to avoid another s-trap situation. If you're going into the wall, that'll be easy to manage. Not sure where you're coming through in the basement if you go down that route. Just make sure you won't hit a floor joist (or any wiring).

Also, don't deck over the top of the trap--at least it sounds like that's what you're aiming for. If that trap ever leaks, you're just soaking your floor. Better to replace a cabinet base in that event, instead of having to redo your subfloor.

Couple things to just double check in your local plumbing code. Can you use AAVs? That'd make venting the sink easier. Do you need an air gap for the dishwasher drain? You don't have one now, but a lot of places require them (it's a little nub that sticks above the sink, so you'd need to drill a hole in your sink or counter to make that happen). You could do a trapped stand-pipe for the dishwasher and filter drains otherwise, but that means having a 2" pipe and trap in there, too, and that'll need to go down to meet the drainpipe in the basement. Doesn't sound like you wanted to ADD things under your sink, though. lol

Sorry if that's over-complicating things, but if you're interested in getting everything to code, may as well research that, and make sure it's all done correctly.

 

[Diehard]

I don't like where the branch piece for the dishwasher drain is in that kit. It's too low. It should be right up by your sink like it is now. With it so low, I'd worry your trap could back up just far enough without the sink backing up, and then you could get water backing up into your dishwasher without the visual feedback of your sink not draining. Just the force from a garbage disposal could send water up that way, too. Yeah, most dishwashers these days have check valves to not allow water coming back in, but better not to test them unnecessarily, in my opinion. The dishwasher hose should be looped as high as possible within the cabinet.
Residential...

Commercial...

You can buy the traps, the y-branch, extensions, and whatever else you might need separately for about the same money, if not cheaper; then you're getting enough flexibility to set it all up better.

Keep in mind you'll need a good 3-4" of straight pipe after the p-trap to avoid another s-trap situation. If you're going into the wall, that'll be easy to manage. Not sure where you're coming through in the basement if you go down that route. Just make sure you won't hit a floor joist (or any wiring). You'll need a vent.

Also, don't deck over the top of the trap--at least it sounds like that's what you're aiming for. If that trap ever leaks, you're just soaking your floor. Better to replace a cabinet base in that event, instead of having to redo your subfloor.

Couple things to just double check in your local plumbing code. Can you use AAVs? Based on the IPC, which appears to be for Delaware, allows them. That'd make venting the sink easier. Do you need an air gap for the dishwasher drain?No! You don't have one now, but a lot of places require them (it's a little nub that sticks above the sink, so you'd need to drill a hole in your sink or counter to make that happen). You could do a trapped stand-pipe for the dishwasher and filter drains otherwise, but that means having a 2" pipe and trap in there, too, and that'll need to go down to meet the drainpipe in the basement. Doesn't sound like you wanted to ADD things under your sink, though. lol

Sorry if that's over-complicating things, but if you're interested in getting everything to code, may as well research that, and make sure it's all done correctly.

Some good points to consider but I added my 2 cents, in red.
Also, here's a link to the IPC which appears to be for Delaware.
https://codes.iccsafe.org/content/IPC2018?site_type=public

 

[JamieRI]

I included my replies in-line below in bold

Helper Dave wrote:
"I don't like where the branch piece for the dishwasher drain is in that kit. It's too low. It should be right up by your sink like it is now. With it so low, I'd worry your trap could back up just far enough without the sink backing up, and then you could get water backing up into your dishwasher without the visual feedback of your sink not draining. Just the force from a garbage disposal could send water up that way, too. Yeah, most dishwashers these days have check valves to not allow water coming back in, but better not to test them unnecessarily, in my opinion.

I agree, thank you.

You can buy the traps, the y-branch, extensions, and whatever else you might need separately for about the same money, if not cheaper; then you're getting enough flexibility to set it all up better.

I am not shopping in stores these days. Online Home Depot had longer delivery times on many of their discrete parts, this kit came faster than anything and seemed to be quite configurable. It arrives today.

Keep in mind you'll need a good 3-4" of straight pipe after the p-trap to avoid another s-trap situation. If you're going into the wall, that'll be easy to manage. Not sure where you're coming through in the basement if you go down that route. Just make sure you won't hit a floor joist (or any wiring).

Was planning to put the trap as far back and down at the floor, making it possibly 24" from the sink basin to the trap weir. The trap arm would run forward toward the front of the cabinet, under my new, removable floor and then turn down the existing hole to meet the horizontal pipe in the basement.

I don't understand why 3-4 inches of trap arm provides relief to my S trap. Does this length of run eliminate siphoning?

Also, don't deck over the top of the trap--at least it sounds like that's what you're aiming for. If that trap ever leaks, you're just soaking your floor. Better to replace a cabinet base in that event, instead of having to redo your subfloor.

I understand this. The cabinet floor I tore out was rotten particle board from a previous copper waste pipe leak that I repaired years ago. But the storage benefit of it being under my new floor is quite appealing, however. Given how the RO filter system, old rotting copper pipes are, etc., I should assume it is IF not WHEN there will be a leak. I can at least put one of my three wireless leak sensors from my Guardian Flood Prevention System there, I don't need two at my boiler. Once the parts come later, I will do a dry fit of all this.

Couple things to just double check in your local plumbing code. Can you use AAVs? That'd make venting the sink easier. Do you need an air gap for the dishwasher drain? You don't have one now, but a lot of places require them (it's a little nub that sticks above the sink, so you'd need to drill a hole in your sink or counter to make that happen). You could do a trapped stand-pipe for the dishwasher and filter drains otherwise, but that means having a 2" pipe and trap in there, too, and that'll need to go down to meet the drainpipe in the basement. Doesn't sound like you wanted to ADD things under your sink, though. lol

The RI code is IPC and AAVs are allowed. I think it would need to attach at the point the trap arm would turn down into the basement, right? Then it has to poke through my removable new cabinet floor right where I want to put a pull-out organizer. Perhaps I could run it horizontally back and then up the back to the AAV? I don't have the wye for that... Or I could skip meeting venting code requirements. If I do that, could test for siphon by draining a sink full of hot water and using my thermal imaging camera to observe the water level in the trap? (like I said, I have never observed odor in the kitchen with the existing S trap there. The basement drain has a 3" roof vent to the right of the picture I attached. Maybe that is obscuring a siphon problem by keeping that pipe vented.

I read IPC 802.1.6 as requiring air gap OR affixing the hose at sink rim or counter. I'll make that change.

Sorry if that's over-complicating things, but if you're interested in getting everything to code, may as well research that, and make sure it's all done correctly.

I am an electrical engineer. Complicated is fun!
Thanks for your thoughtful reply!

 

[JamieRI]

Some good points to consider but I added my 2 cents, in red.
Also, here's a link to the IPC which appears to be for Delaware.
https:/ [QUOTE="Diehard, post: 124186, mem...PC2018?site_type=public[/FONT][/SIZE][/QUOTE]

Thanks, Diehard, I see where you said "You'll need a vent" and I agree if I stick with meeting code, or if not but there is a proven siphon happening. That means I need to buy more parts and put it off, which I can. Also thanks for the looping the hose requirement. I didn't understand the theory behind the code at first, but I think maybe it is to allow the hose to drain out after the dishwasher completes, and keep any kitchen or disposal waste from flowing or siphoning backwards toward a dishwasher that may lack a check valve.

 

[JamieRI]

I can't speak to anything else, but years ago I put an RO system in - Water tap at sink, and feed to icemaker.
Before I bought it, checked with Seller, and learned I could put it in the basement (high-up), and it would still work. Ther's lots of fine detail work to put it in that cabinet, but it's easy to run 1/4" tubing up from the basement to wherever you want or need it.
.

I will re-consider this idea. I am worried about all the stuff under there, yet I was worried about the added head of probably 3 more feet. One RO vendor said they run slowly as it is and didn't recommend putting it downstairs. I can test adding three feet by just holding the end of the discharge hose over my head toward the sink. They flow rate also decreases over time I think. I am new to these filters.

 

[frodo]

My goodness that plumbing is UGLY

These are my thoughts

Go under the floor an cut the 2'' pipe.. pull every thing you have installed out
bring the 2'' UP through the floor. install a 2 x 1 1/2'' wye. point the side outlet [1 1/2] of the wye to the back RH corner of the cabinet. Install a clean out fitting on the top of the wye.

at the back ,of the cabinet, install a 1 1/2'' tee with . then continue the 1 1/2 pipe UP and install an AAV
as lose to the bottom of the cabinet as possible

Out the side of the tee. install a 1 1/2'' x 1 1/2'' slip joint trap adapter
install a 1 /2'' ptrap in that adapter
install a 1 1/2'' continuous garbage disposal waste
TURN the disposal to line up with the continues waste. REMOVE the existing elbow that is bolted to te disposal. hook the continues waste to that opening

Re route the dishwasher drain hose to the disposal. remove the ''knock out'' in the disposal install the hose.

on top of the tee at the ptrap. install a wye branch tail piece. hok the RO tube to that
hook the sink to the top of the wye branch using a flat tail piece

 

[JamieRI]

My responses in bold
frodo wrote
"Go under the floor an cut the 2'' pipe.. pull every thing you have installed out
bring the 2'' UP through the floor.

install a 2 x 1 1/2'' wye. point the side outlet [1 1/2] of the wye to the back RH corner of the cabinet. Install a clean out fitting on the top of the wye.

Does this create a 24" run of waste pipe at 45 degrees? Is that OK?
Also, it would be in the space I would like to put a pull-out organizer. Could I instead use a reducing tee and run that horizontally to the back right of the cabinet, a 90 up to a tee for the P trap and continuing up to the AAV?

at the back ,of the cabinet, install a 1 1/2'' tee with . then continue the 1 1/2 pipe UP and install an AAV
as lose to the bottom of the cabinet as possible

Out the side of the tee. install a 1 1/2'' x 1 1/2'' slip joint trap adapter
install a 1 /2'' ptrap in that adapter
install a 1 1/2'' continuous garbage disposal waste
TURN the disposal to line up with the continues waste. REMOVE the existing elbow that is bolted to te disposal. hook the continues waste to that opening
I like the continuous garbage disposal waste. Straight, and elevated.

Re route the dishwasher drain hose to the disposal. remove the ''knock out'' in the disposal install the hose.
Love this.

on top of the tee at the ptrap. install a wye branch tail piece. hok the RO tube to that
hook the sink to the top of the wye branch using a flat tail piece

So, this is clean, sturdy, and not hard to do once I buy more parts. I was hoping to push the P trap to the back of the cabinet by using the HD rig, which does put the right sink offset from the trap, but that always happens with one sink in a double sink anyway, right?

Thanks Frodo!

 

[frodo]

My responses in bold
frodo wrote
"Go under the floor an cut the 2'' pipe.. pull every thing you have installed out
bring the 2'' UP through the floor.

install a 2 x 1 1/2'' wye. point the side outlet [1 1/2] of the wye to the back RH corner of the cabinet. Install a clean out fitting on the top of the wye.

Does this create a 24" run of waste pipe at 45 degrees? Is that OK?
Also, it would be in the space I would like to put a pull-out organizer. Could I instead use a reducing tee View attachment 23992and run that horizontally to the back right of the cabinet, a 90 up to a tee for the P trap and continuing up to the AAV?

at the back ,of the cabinet, install a 1 1/2'' tee with . then continue the 1 1/2 pipe UP and install an AAV
as lose to the bottom of the cabinet as possible

Out the side of the tee. install a 1 1/2'' x 1 1/2'' slip joint trap adapter
install a 1 /2'' ptrap in that adapter
install a 1 1/2'' continuous garbage disposal waste
TURN the disposal to line up with the continues waste. REMOVE the existing elbow that is bolted to te disposal. hook the continues waste to that opening
I like the continuous garbage disposal waste. Straight, and elevated.

Re route the dishwasher drain hose to the disposal. remove the ''knock out'' in the disposal install the hose.
Love this.

on top of the tee at the ptrap. install a wye branch tail piece. hok the RO tube to that
hook the sink to the top of the wye branch using a flat tail piece

So, this is clean, sturdy, and not hard to do once I buy more parts. I was hoping to push the P trap to the back of the cabinet by using the HD rig, which does put the right sink offset from the trap, but that always happens with one sink in a double sink anyway, right?

Thanks Frodo!

YES....Per code you could use a tee and 90 to offset to the back of the cabinet
BUT..A tee and 90 do not give you the sweep that a 45 degree offset does
In plumbing, the less offsets the better.

Instead of offsetting the wye to the back corner
use the wye. but offset Directly back. just like you wanted to do with a tee and 90
this will give you the room for your shelf. and still put your piping tucked back out the way