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Successfully eliminated “P” trap under sink with Hepvo valve

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  • YanniLazarusYanniLazarus Member Posts: 366
    this is my installation in aT@B320S 2020 model.   With the drain on the left of the sink it was hard to get a straight shot to the corner waste line to work.   Using a 1 1/2" threaded plastic nipple (black plastic) just below the sink drain kept everything as high as I could get it,  and the drain line is as short as possible.   Very happy! 
    Yanni Lazarus 2020 T@B320S, 2018 RAV4 Adventure, Central CT
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  • DalehelmanDalehelman Member Posts: 2,414
    You should have been able to connect the Hepvo directly to the bottom of the sink. There by gaining another 3 or 4 inches. 

    1. Hash  T@B Fun
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  • YanniLazarusYanniLazarus Member Posts: 366
    I couldn't get that to work- my sink drain is closer to the corner than yours,  so your horizontal run came low enough on the stack to get the fittings to work.   I just dropped mine the 1 1/2 inches for the nipple.  My drain location made it harder. 
    Yanni Lazarus 2020 T@B320S, 2018 RAV4 Adventure, Central CT
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  • YanniLazarusYanniLazarus Member Posts: 366
    Hmmm. Plus the fittings. So you are right. Probably around 3 inches lost- but since my drain is closer to the corner,  overall not so bad. 
    Yanni Lazarus 2020 T@B320S, 2018 RAV4 Adventure, Central CT
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  • DudleeDudlee Member Posts: 24
    I was wondering if pulling the sink up and rotating it 180 to get the drain away from the corner would be worth it.  The install photo of jkjenn Looks like that’s what the crew did?
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  • DalehelmanDalehelman Member Posts: 2,414
    Still looks good.
    1. Hash  T@B Fun
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  • YanniLazarusYanniLazarus Member Posts: 366
    I think if I were smarter and used other fittings it might have worked a bit better.   The slip fittings I used required some minimum tubing lengths.  I do think keeping the horizontal run as short as possible is best (and laziness) kept me from exploring rotating the sink. 
    Yanni Lazarus 2020 T@B320S, 2018 RAV4 Adventure, Central CT
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  • ReenieGReenieG Member Posts: 283
    @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.

    @ScottG Yes, I have no doubt the pic I took which Dalehelman circled is MY undersink piping. :D I guess my "confusion" is that in that pic I posted of my T@B where Dalehelman circled, I don't see a vent. I will have to actually LOOK and see for myself I suppose, lol. 

    2018 T@B 320S / 2024 Chevy Blazer RS AWD / Phoenix, AZ
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  • VictoriaPVictoriaP Member Posts: 1,496
    ReenieG said:
    @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.

    @ScottG Yes, I have no doubt the pic I took which Dalehelman circled is MY undersink piping. :D I guess my "confusion" is that in that pic I posted of my T@B where Dalehelman circled, I don't see a vent. I will have to actually LOOK and see for myself I suppose, lol. 

    @reenieG The circled area in that pic IS part of the vent stack, the 90° elbow above where the sink drain attaches to the vertical pipe leads to the horizontal pipe behind the toilet and exits (vents) out the driver’s side of the trailer. 

    2019 320s BD Lite, white with blue (“Haven”)
    2015 Subaru Outback 3.6r (unsafe 200lb tongue weight limit until 2020 models)
    2020 Subaru Outback XT
    Pacific NW
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  • Kr@ckenKr@cken Member Posts: 146
    Another newbie question. What would I want to replace my P trap. Is this something that is recommended?
    Kr@cken
    2020 T@B 320 Boondock
    Factory Victron Solar, Norcold 3 way Fridge
    Clueless about everything electronic
    2020 Subaru Ascent 
    Bainbridge Island, Wa
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  • Sharon_is_SAMSharon_is_SAM Member Posts: 10,060
    It is done to free up space under the sink as the “p” hangs down lower and the Hepvo can be mounted parallel to the floor.  What kind of trap do you have under your sink in the 2020 Boondock?
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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  • Travelin3DTravelin3D Member Posts: 174
    I just did this mod in June on my 2020 320 BDL. Here’s a before and after.

    Richie, Mickie and Satchmo
    2020 320S Boondock Lite (silver w/blue)
    2019 Subaru Ascent Premium
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  • GatorEggGatorEgg Member Posts: 482
    Nice.  But the ptrap keeps my Keurig kcup secure in there. 😬
    2022 TAB 400 Boondock, 2019 Toyota Tacoma Sport 4x4
    2018 TAB 320 Boondock (previous)
    Odessa, Fl.  

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  • TXMacDadTXMacDad Member Posts: 2
    Our sink mod in 2014 T@B 

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  • rcarlson1957rcarlson1957 Member Posts: 264
    Finished mine yesterday. 
    2018 TAB 320S Silver/Black w/100ah Lithium/Bluetti Solar Battery & Portable Solar Panels
    2020 Honda Ridgeline RTL (AWD) Lunar Silver Metallic w/Bluetti Charger 1
    North Texas - Retired Air Force/Corporate Trainer
    Trips - 48  Mileage - 63,452
    "Our favorite trip will always be our next one"
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  • Denny16Denny16 Member Posts: 5,431
    Looking good...   =)
    cheers
    2018 TaB400 Custom Boondock,  Jeep Gladiator truck, Northern California Coast.
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  • ReenieGReenieG Member Posts: 283
    edited September 2021
    I finally did mine. There was alot of buildup in the p-trap, probably from water evaporation when storing. Just hoping this all doesn't leak! I'm always leery of plumbing fittings when I glue them together, although it's more me than them.
    I'm planning on replacing the faucet with a mod I saw from Facebook (link to faucet) and possibly replacing the sink, (link to sink) since it would prob still be doable. (sink is reportedly 1" deeper) Since I used a flex drain fitting I may still be able to mod the sink, although I'm still considering the microwave install under the sink which I think might be sink OR microwave, not both. We'll see after the faucet install.

    2018 T@B 320S / 2024 Chevy Blazer RS AWD / Phoenix, AZ
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  • ReenieGReenieG Member Posts: 283
    edited September 2021
    @Dalehelman @LittleBoyBlue I like your mod appearances better than mine. Not sure why mine looks slanted in the final pic. Hmmm... It looks like your mod might have been easier to do with those white connections. If mine leaks, I'm copying yours, lol.
    2018 T@B 320S / 2024 Chevy Blazer RS AWD / Phoenix, AZ
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  • GPS_JonGPS_Jon Member Posts: 2
    edited April 7
    I did this one.   My first post   2019 320 SBD. The sink didn’t let me route directly to the drain. 

    Is the black drain pipe securely mounted to the grey tank?  Mine isn’t and can be lifted up and down inside lower cabinet. 
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  • ScottGScottG Administrator Posts: 5,654
    Good question. My guess--and that's all it is--is that the black drain enters the grey tank through a rubber flange of some sort. This would allow a bit of movement as the trailer gets banged six ways from Sunday rolling down road.
    2015 T@B Max S (320)
    2015 Nissan Frontier SV V6 4x4
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  • AnOldURAnOldUR Member Posts: 1,707
    edited April 4
    @GPS_Jon
    Another non-plumber person who used the rubber couplers rather than PVC glue.
    I kept the p-trap. Swung it to the back out of the way.

    Stockton, New Jersey
    2020 nuCamp T@B 320S * Jeep Wrangler
    60,865 camping miles through the end of 2025

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  • GPS_JonGPS_Jon Member Posts: 2
    edited April 5
    AnOldUR said:
    @GPS_Jon
    Another non-plumber person who used the rubber couplers rather than PVC glue.
    I kept the p-trap. Swung it to the back out of the way.

    I like your setup.  More room without spending money on the waterless trap. I used the Fernco couplers so I could rotate the sweep and not use a T. I might have gone with your approach if I saw it first. Either way, for the extra room in that cabinet it’s worth the modification. 

    I filled up the sink and pulled the stopper.  The sink drained quickly and most of the water went into the grey tank.  There was maybe two cups on the ground.  My black pvc pipe must not be seated in the tank.  I’ll have to pull the shroud and see if I can get eyes on it.  The plumbing I added had no leaks.  
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  • ScottGScottG Administrator Posts: 5,654
    edited April 6
    GPS_Jon said:
    ...
    I filled up the sink and pulled the stopper.  The sink drained quickly and most of the water went into the grey tank.  There was maybe two cups on the ground.  My black pvc pipe must not be seated in the tank.  I’ll have to pull the shroud and see if I can get eyes on it.  The plumbing I added had no leaks.  
    In light of this, I retract my earlier guess about the rubber flange. Given the amount of leakage I'd say your drain pipe has parted ways with your grey tank. Please report back what you find and, if applicable, how you fix it.

    2015 T@B Max S (320)
    2015 Nissan Frontier SV V6 4x4
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  • pthomas745pthomas745 Administrator, Moderator Posts: 4,504
    Back in December, @jimcenname installed this "bottle trap" in his trailer.  Looks like a simpler install to me, someone with very limited plumbing experience.


    Looks like this:


    2017 Outback
    Towed by 2014 Touareg TDi
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  • jimcennamejimcenname Member Posts: 343
    pthomas745 said:
    Back in December, @jimcenname installed this "bottle trap" in his trailer.  Looks like a simpler install to me, someone with very limited plumbing experience.


    Looks like this:


    It's still working well for me. No leaking. 
    2019 T@B400
    TV: 2017 Nissan Frontier SV 4X4
    Southern California
    Full-timer since 2019
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