Successfully eliminated “P” trap under sink with Hepvo valve

MuttonChops · March 2018

dsatwork said:

@Sandiegogal Our next mod......this will eliminate the weird smell in the trailer. HepvO® valve.... who knew this even existed? The HepvO® valve means enhanced plumbing design and system efficiency, without compromising performance or risking the escape of foul air into the living space from the drain or sewer.

This appears to be a great product to increase usable cabinet space and will be added to my project wish list. Everyone however should remember a sink HepvO valve only addresses half the weird smell problem.

The Shower Floor Drain has another P-type drain that can/will dry out.
Amazon lists a waterless trap designed for shower floor usage, Wirquin Slim Extra Flat Low Profile Shower Trap. Would expect installing that one is a bit more than a Saturday afternoon project.

There is also a commercial liquid product to seal off the drain so the water does not evaporate. It does require reapplication after the drain is flushed but might be helpful on long periods of storage . . . of course it's not cheap.

Everprime by waterless.com Long Lasting - No Evaporation

Think I'll just try to remember to keep the traps wet for now.

LittleBoyBlue · April 2018

Thanks for all of your information about the parts that Home Depot carries. I ordered them online and picked the up at my local store. Bought the HepvO online from Amazon and got a good deal since it was an "open box" but new. The one hiccup I ran into is my 2018 T@B S sink has the drain off set and there wasn't enough room to connect everything. Good new was Home Depot carried the additional part and it wasn't expensive. A flex tube to allow me to connect everything. Photos are attached. Got lots of room now. No leaks

Here's the part number for the flex coupling.

Model # C3522355

Internet #205154096

Store SKU #1000049742

Homebodyatheart · April 2018

@LittleBoyBlue I really like your mod! My sink is also offset (2107 Tab320S) and this would give me some more space. Thanks for sharing!

Dalehelman · April 2018

@LittleBoyBlue
Nice work.

dougm · April 2018

I have a 2018 T@B 320S and appreciated @LittleBoyBlue pointing out that in his 2018 model there was not enough space between the sink drain and the vertical ABS drain pipe and to connect the hepvo and 90 degree elbow combo. I was able to use to two 90 deg 1 1/2" PVC elbows that I found at my local ACE hardware store. I learned that this slip joint to tube configuration is called a waste arm. I hope this mod will be helpful to others wishing to install a Hepvo to save space under the sink. It creates a lot of new usable space under the sink and seems to work great. With the help of the pictures, parts list and excellent guidance provided by @Dalehelman, once I had all of the parts in hand, it took only about an hour to complete this mod.

Ace 1-1/2 in. Tube x 1-1/2 in. Dia. FPT Plastic Waste Arm(ACE101AW)

http://www.acehardware.com/product/index.jsp?productId=28944706

Image: https://us.v-cdn.net/5021717/uploads/editor/ie/cx2ir3lp3hw9.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/44/8psxhl33es36.jpg

Dalehelman · April 2018

@dougm nice work.

dougm · April 2018

Thank you @Dalehelman for leading the way!

BrianZ · May 2018

Once again, thank you @Dalehelman, for the inspiration to do another of your mods, and to other contributors like @ChanW and @dougm for your solutions using alternative parts & configurations. I used a combination of all your tips to get it done yesterday.

Image: https://us.v-cdn.net/5021717/uploads/editor/c9/bo62gtz93cdc.jpg

Here's my before & after shots showing how we went from only 3 inches of space left under the drain to 10 inches.

Image: https://us.v-cdn.net/5021717/uploads/editor/kl/mju8rvc2i3fy.jpg

This shows what was removed. I made sure to dry-fit everything together before cutting the pipes, including making sure the parts could be telescoped together in order to expand them to fit between the pipes' cut ends. I also tried to leave as much pipe remaining as possible, in case future repairs ever become necessary.

Image: https://us.v-cdn.net/5021717/uploads/editor/nz/de5ba3al6ila.jpg

View from inside right of cabinet. To clarify where the various parts are used & how they are connected, I have labeled the types of joints made and the location of parts numbered by sources listed below (Amazon & Lowe's)..

(1) HEPVO 1-1/2 TRAP, Amazon: $33
(Note: the included straight adapter piece was not used, just the elbow)

(2) NIBCO 1-1/2-in dia ABS Trap Adapter Fitting

Item # 75356 Model # CL5801-7, Lowe's: $1.80

(Qty: 2, glued to cut ends of pipe with pvc cement)
(3)Keeney 1-1/2-in Plastic Slip Joint End Outlet Continuous Waste

Item # 25032 Model # 125-16WK, Lowe's: $5.98

(includes drain outlet & elbow)
(4) Keeney Mfg. Co. 1-1/2-in Plastic Elbow Coupling

Item # 172271 Model # 104AWK, Lowe's: $4.99

(a second elbow)
(*) = 2.5" pieces of pipe cut from leftover pieces trimmed from the long arms of the elbows. The bottom of the vertical drain was trimmed also. Note that I chose to reverse the direction of the lower elbow so the extra joint would be in the vertical section.

I was able to use the same drain outlet (3) that Dale used, but in the intended orientation without modification, since I had to mount it lower anyway due to the later model T@Bs' drain being located closer to the pipe, as previously noted.

Image: https://us.v-cdn.net/5021717/uploads/editor/t7/01k2tmbeqbao.jpg

Another view of the entire finished space, including my DIY towel rack. It's made from a bent 3/8" aluminum rod & hanger tabs made of strips cut from a clear plastic coke bottle and a couple of screws. I could have made it a bit shallower, but this is not a full roll either.

BrianZ · May 2018

PS: Regarding that issue about whether a vent pipe is required by the Hepvo waterless trap, I came across a story (in an Amazon review maybe) where someone was dissatisfied after installing the device on pipes without any vent. Apparently, the pipes got heated by the sun, causing air inside to expand which pushed on the rubber bladder inside, turning it inside out so it became a one-way valve in the opposite direction, so the drain could no longer drain!

I just found it funny that someone would install a trap in non-standard plumbing and then complain about its performance. Maybe that's one application where a water traps might have an advantage, but situations can be vary.

Dalehelman · May 2018

@BrianZ
Awesome write up.

ChanW · May 2018

Thanks for the creative thinking on @Dalehelman's project here @BrianZ and @dougm! I'd almost given up on the idea, cuz I couldn't got it into that space.

I'm a bit jealous though, because our drain pipe goes out the front left bottom corner of the cupboard, rather than the rear, as yours do...

Michigan_Mike · August 2018

I decided to create added space under the sink via Linda's prodding in the new T@B 400. Seriously, cutting out new, never used plumbing and risking a nick in the new trailer!!!?

Ummm, okay honey!

So I completed this mod prior to leaving on our shakedown trip a week ago and wanted to pass along some information/observations and tips if you will. My special thanks to Dale and the many others who contributed as this is a great-space-saving 5-star mod and is something the factory should do as it falls into line with "limited space" thinking and is beneficial too.

I recommend that people look the area over closely as there are control cables for the Alde, Kool Kat, etc. running inside the cabinet wall area that could be damaged when cutting the pipe, but this process can be done easily with just being aware that it's there and in close proximity.

Here is a shot of the air admittance valve that was at the top of my sink plumbing and it seemed to hover in the spot beneath the counter-top after I made the cut with my small hand-held hacksaw. I tugged on it and it dropped down so I was amazed to see it and realized then that things wouldn't be too bad going forward with this mod. So as noted in the photo below I unscrewed the valve from the fitting as space seemed to be limited in the area.

Image: https://us.v-cdn.net/5021717/uploads/editor/vj/qqv87mzrqak7.jpg

So once I cut out the pipe and the air valve dropped down this is what it looked like after I cleaned out the area with a damp paper towel and cloth and removed all the fine black plastic pipe particles. The particles do cling to the wall and cabinet sides, so the damp cloth does help and easily cleans things up.

Image: https://us.v-cdn.net/5021717/uploads/editor/hf/pimgp2330uex.jpg

From that point on it basically is cleaning the pipe ends, applying glue to the pipe and installing the 1-1/2" ABS DWV Hub (found these parts at Lowe's), plastic tee fitting, cutting/adapting some small pieces of pipe to join things together, installing the Hepvo valve and tightening things up.

Image: https://us.v-cdn.net/5021717/uploads/editor/ch/dai6ctuaotj6.jpg

I did take the old fitting below the air admittance valve, cut off the female threaded end and joined the valve to the T fitting as I was unable to find a 1-1/2 threaded piece. You can see this in the last photo below.

It does take some fiddling around, measuring, unscrewing, refitting, etc. but it's worth the effort and contorted position your body is in and after a few ibuprofen you'll feel like a million dollars once it's done!

Image: https://us.v-cdn.net/5021717/uploads/editor/kc/n4my0913xekz.jpg

And this is what sits below the sink today.... Tada!!!!!!

Image: https://us.v-cdn.net/5021717/uploads/editor/4c/kjbpr8yzc1lm.jpg

Dalehelman · August 2018

@Michigan_Mike
The one YouTube video I watched said that you can eliminate air vent in your application. The application in my T@B required reconnecting the vent pipe since it also vents the black tank.

Michigan_Mike · August 2018

Dalehelman said:

@Michigan_Mike
The one YouTube video I watched said that you can eliminate air vent in your application. The application in my T@B required reconnecting the vent pipe since it also vents the black tank.

I didn't want to take any chances and figured I better leave it in place. Once I figured out the threaded end issue it went well as my feet were getting tired looking for a threaded female end at Lowe's. That's a great mod Dale and it didn't take long for Linda to use up the available space!

Dalehelman · August 2018

I left the vent on Verna’s when I did hers as well. Happy life.

jkjenn · April 2019

@Dalehelman, once again thanks for a genius mod. Austin and the crew installed the Hepvo valve for me. What a difference, especially since my freshwater tank is in the bottom cupboard, so the top one is all I have.

ReenieG · September 2020

I found this pic on Amazon. I don't know what type of trailer this is, but my question is, does it matter if the HepvO valve is vertical or horizontal? This looks like a really nice clean install. I'm hoping to make enough room for a microwave under my sink, like @Marco did and I'd like to try something like this.

Image: https://us.v-cdn.net/5021717/uploads/editor/x2/estabhxduoj4.jpg

Sharon_is_SAM · September 2020

I just watched an install video and they said it can be installed horizontally or vertically.

Dalehelman · September 2020

Correct it will work either way. The picture does not show a vent pipe. T@Bs have a vent that needs to be maintained at least on the 320s. The 400 and the new cassette toilets may not.The vent pipe vents both gray and black tanks.

ReenieG · September 2020

jkjenn said:

@Dalehelman, once again thanks for a genius mod. Austin and the crew installed the Hepvo valve for me. What a difference, especially since my freshwater tank is in the bottom cupboard, so the top one is all I have.

@jkjenn who are "Austin and crew"? Inquiring minds... you know...

@Dalehelman, where is the vent pipe on this thing or did jkjenn's "crew" install remove or relocate it? My 2018 T@B 320S is in storage so I'd have to drive over there to have a(nother) look but I don't see it in my pic... I also saw on another earlier post that you first shortened the length of the P trap and then rotated it back, but looks like you now added the Hepvo valve or is that a different trailer? Any thoughts on the pros and cons you can share on the 2 different setups? TIA

Image: https://us.v-cdn.net/5021717/uploads/editor/0b/4vq7k70lbnwd.jpg

Dalehelman · September 2020

ScottG · September 2020

Hepco or not, I agree with Dalehelman that the vent on the 320 needs to be maintained.

The drain from the kitchen sink is also the vent (and the only vent) from the grey tank. It joins a similar pipe rising from the black tank just after it passes through the wall at the top of the cabinet. A single pipe then continues to the vent opening on the driver's side of the trailer.

ReenieG · September 2020

ScottG said:

Hepco or not, I agree with Dalehelman that the vent on the 320 needs to be maintained.

The drain from the kitchen sink is also the vent (and the only vent) from the grey tank. It joins a similar pipe rising from the black tank just after it passes through the wall at the top of the cabinet. A single pipe then continues to the vent opening on the driver's side of the trailer.

@ScottG, I'm not disagreeing, I just don't see a vent in the pics. So, to me, it doesn't look like these mods or my 320 has one. Maybe if I actually looked at the pipes?

ReenieG · September 2020

Sharon_is_SAM said:

I just watched an install video and they said it can be installed horizontally or vertically.

@Sharon_is_SAM do you have a link to the video?

Sharon_is_SAM · September 2020

https://youtu.be/de9n5YbZBTw

This is a different one, but it shows the actual packaging with vertical or horizontal.

Sharon_is_SAM · September 2020

@ReenieG - although the valve itself does not need a vent, the plumbing on the TaBs share a vent and if the sink trap is altered, the plumbing still must be vented.

Sharon_is_SAM · September 2020

ReenieG said:

ScottG said:

Hepco or not, I agree with Dalehelman that the vent on the 320 needs to be maintained.

The drain from the kitchen sink is also the vent (and the only vent) from the grey tank. It joins a similar pipe rising from the black tank just after it passes through the wall at the top of the cabinet. A single pipe then continues to the vent opening on the driver's side of the trailer.

@ScottG, I'm not disagreeing, I just don't see a vent in the pics. So, to me, it doesn't look like these mods or my 320 has one. Maybe if I actually looked at the pipes?

@ReenieG

Dale’s picture has the vent pipe circled. The black pipe extends to a vent on the side of the TaB. This pipe also vents the black tank.

This TaB 400 sink mod picture has the vent to the left, just barely viewable.

ScottG · September 2020

ReenieG said:

ScottG said:

Hepco or not, I agree with Dalehelman that the vent on the 320 needs to be maintained.

The drain from the kitchen sink is also the vent (and the only vent) from the grey tank. It joins a similar pipe rising from the black tank just after it passes through the wall at the top of the cabinet. A single pipe then continues to the vent opening on the driver's side of the trailer.

@ScottG, I'm not disagreeing, I just don't see a vent in the pics. So, to me, it doesn't look like these mods or my 320 has one. Maybe if I actually looked at the pipes?

@ReenieG, I agree with regard to the original pic you posted--there is no vent on the sink drain, and that suggests the Hepco valve itself does not require a vent to function properly.

Regardless, the grey tank itself must still be vented to prevent pressure from impeding drainage. I assume in your pic (which is not a T@B) the grey tank is probably vented in another location that is more convenient for the layout of that particular camper.

If you go look at your 320 I'll bet a nickel it looks like the pictures Dalehelman posted with the vent in place.

Dalehelman · September 2020

I tried eliminating the gray water vent. If you do the air in the tank has no where to go when the sink drains so it will bubble up through the shower. Along with any fumes in the gray tank. Not good.

Dalehelman · September 2020

ReenieG said:

I found this pic on Amazon. I don't know what type of trailer this is, but my question is, does it matter if the HepvO valve is vertical or horizontal? This looks like a really nice clean install. I'm hoping to make enough room for a microwave under my sink, like @Marco did and I'd like to try something like this.

This is not a T@B installation.

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Successfully eliminated “P” trap under sink with Hepvo valve

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Model # C3522355

Internet #205154096

Store SKU #1000049742

Ace 1-1/2 in. Tube x 1-1/2 in. Dia. FPT Plastic Waste Arm(ACE101AW)