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  • Grey Tanks - Open or Closed

    Hello All,
    I have a question regarding the Grey Tanks on a 2020 GD Imagine 2670MK.
    We are currently on a Seasonal Site and connected to City water.
    Is it OK to leave one or both of these tanks open..?
    I have a Rhino Blaster hooked up all the time and use the Tank Cleanout connection every time the Black tank is emptied.
    Thanks in advance,
    Randy G​
    2021 GMC Sierra Evolution 3.0 Turbo Diesel
    2020 Gran Design 2670 MK
    Randy & Janice
    Tow Vehicle - 2021 GMC Sierra, 3.0 Turbo Diesel
    2020 Grand Design Imagine 2670MK

  • #2
    In my opinion it’s best to keep the valves closed. One for flushing the slinky with a big whoosh after dumping black. Also, when others dump there may be gasses that want to come up into your tanks via the sewer system. While gas will theoretically exhaust via the roof vent best not to let ‘em in. Plus these campground systems are not exactly sealed everywhere. Who knows what might be crawling around down there. Ha.

    Comment


    • #3
      It's recommended to not leave the valves open due to the possibility of critters finding their way up into the plumbing system of the unit. Likewise, leaving the grey tanks open can also lead to solids being left behind. While grey water is not a heavy with solids, they are there.
      Joseph
      Tow
      Vehicle: 2018 GMC K2500 Denali Diesel
      Coach: 303RLS Delivered March 5, 2021
      South of Houston Texas

      Comment


      • #4
        Further to the previous comments (which I agree with) . . . leaving the grey gate valves open will allow the gate valve seals to dry out. You don’t want this. Better to let the grey tanks fill and empty them by cycling the gate valves.

        Rob
        Cate & Rob
        (with Border Collies Molly & Angel)
        2015 Reflection 303RLS
        2022 F350 Diesel CC SB SRW Lariat
        Bayham, Ontario, Canada

        Comment


        • #5
          I agree with all of the above. However, I leave my grey tank open, except when traveling or dumping the black tank.

          We are full timers and can fill the grey up in two to three days, so it became a daily task to empty the grey using the cable pull which has a 180-degree tight bend in it. After numerous times when the valve did not close completely no matter how many times I pushed on the cable, and replacing and rerouting the cable twice to ease the bend, I gave up and started leaving the valve open when connected to a sewer.

          As noted above, I do close the valve when dumping the black tank, whether it actually closes completely or not I don't know. But it seems to close enough to keep the solids out of the grey tank.
          John
          2018 Momentum 395M
          2018 Ram 3500 Dually
          Every day is a Saturday, but with no lawn to mow.

          Comment


          • #6
            Originally posted by Cate&Rob View Post
            Further to the previous comments (which I agree with) . . . leaving the grey gate valves open will allow the gate valve seals to dry out. You don’t want this. Better to let the grey tanks fill and empty them by cycling the gate valves.

            Rob
            I never let my tanks dry out since this also prevents issues with the sensors. Our sensors still work like new even though they provide an estimation at best. Minimal water is left in the tanks after flushing or anti-freeze in the winter to keep the tanks and seals wet. The cable systems seem like an additional hassle where my good ol fashion direct T handle valves just work. The seals can be sprayed with CRC food grade silicone to easy in their operation but should still stay wet to prevent deterioration.

            Jim
            2017 Imagine 2600RB
            2015 GMC Sierra 4x4

            Comment


            • #7
              JBill9694John, You should put one of the https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 at the interface between the flex hose and the camper. This will allow you to leave the grey valves open, but close the system from the public sewer. Since it's outside of the camper, much easier to deal with and will give you a little extra storage since the lines to the valve will also be included in the volume.
              Joseph
              Tow
              Vehicle: 2018 GMC K2500 Denali Diesel
              Coach: 303RLS Delivered March 5, 2021
              South of Houston Texas

              Comment


              • #8
                Yes, Joe, I have this on both drain lines. Not because of leave the grey tank open when connected, but because I've been surprised by the sploosh too many times when setting up. And it isn't always grey water that splooshes. Why we can't have idiot lights to tell us when the valves are closed, I don't know. I mean its not critical like on a submarine or something, but still depending on pushing what amounts to a stiff string to close a valve is not a sure thing. By the way, has everyone figured out that when the cable springs back after you pushed on it that doesn't mean that the valve is closed. It means that the cable and it's sheath deflected somewhere along the line, probably at a bend and then returned to its relaxed position.

                Anyways, the front drain line for the grey and black tank exits under a slide and I have to go to my knees to access it when we are set up. Not something me knees want to do daily. Also, even though we work to avoid it, sometimes we do get into freezing temperatures and having a pipe full of water outside the heat zone is not something I want to risk.

                I'm not saying that what I'm doing is right for everyone, but it is right for me. I do encourage everyone with the cable attachments to do all that they can to make bends gradual and to anchor the sheath every 2' if not more often. If the cable springs back after the cable is pushed in, force is going to flexing the cable and the sheath, not to closing the valve.

                John
                2018 Momentum 395M
                2018 Ram 3500 Dually
                Every day is a Saturday, but with no lawn to mow.

                Comment


                • #9
                  We are at a full hookup site at this time and both valves will remain off until the tanks are full. Same routine as in any other site to open the black then follow up with the grey when needed. Then close both valves until we need to open them again.

                  Once we get ready to leave I will go through the same process but will follow up with a thorough cleaning with the black tank flush, then set the tank up for the next trip. There really is no need to leave the valves open to risk sewer gasses from entering the rig. Remember under certain conditions with the bathroom exhaust fan turned on, flushing can pull in gasses from the tank. With an open black tank valve, you could be pulling in gasses from the campground in this situation.

                  Leaving the grey valve open adds risk in a situation where the AAV could be leaking and allow sewer gasses to enter the rig.

                  Jim
                  Last edited by MidwestCamper; 09-30-2022, 01:41 PM.
                  2017 Imagine 2600RB
                  2015 GMC Sierra 4x4

                  Comment


                  • #10
                    All my drain lines to the grey tank have P-traps in them, including the shower. I would need a much more powerful vent fan, something along the lines of a jet turbine, to pull the water from the P-traps so that sewer gas could enter trailer.

                    My black tank drain valve is closed except when draining the tank.
                    John
                    2018 Momentum 395M
                    2018 Ram 3500 Dually
                    Every day is a Saturday, but with no lawn to mow.

                    Comment


                    • #11
                      If you leave the grey tank gate valves open, you are venting the campground sewer system through your trailer roof vent. This may not be a problem, but not something that I would leave open all the time.

                      Rob
                      Cate & Rob
                      (with Border Collies Molly & Angel)
                      2015 Reflection 303RLS
                      2022 F350 Diesel CC SB SRW Lariat
                      Bayham, Ontario, Canada

                      Comment


                      • #12
                        Originally posted by Cate&Rob View Post
                        If you leave the grey tank gate valves open, you are venting the campground sewer system through your trailer roof vent. This may not be a problem, but not something that I would leave open all the time.

                        Rob
                        This is why I've followed your advice (posted long ago in another thread) about establishing a "trap" in the stinky slinky line. There are times I have to leave the valves open (like when the DW is using the washer since it uses so much water--very easy to overwhelm the storage capacity). The trap in the stinky line keeps out the gasses and (hopefully) unwanted visitors living in the campground's sewer.
                        Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                        2017 Ford F-350 DRW, '19 315RLTSPlus

                        Comment


                        • #13
                          Even with traps, a leaking AAV valve will allow campground gasses to enter the rig. Bad enough to have our own gasses leaking in if the valve was questionable but I would not want everyone else's gasses too. It not difficult to open the tank valves when the tank is full. Our Imagine has close to 75 gallons of grey capacity. Sewer gasses up the grey stack can also be breathed in at the campsite under the right conditions.

                          Jim
                          2017 Imagine 2600RB
                          2015 GMC Sierra 4x4

                          Comment


                          • #14
                            Originally posted by MidwestCamper View Post
                            Sewer gasses up the grey stack can also be breathed in at the campsite under the right conditions.
                            This is very true . . . on our Reflection 303, the vent stack is directly behind the opening end of the bathroom hatch. Definitely a what were they thinking? construction detail. If the wind is blowing the wrong way we have to keep that hatch closed, even with the gate valves closed.

                            Rob

                            Cate & Rob
                            (with Border Collies Molly & Angel)
                            2015 Reflection 303RLS
                            2022 F350 Diesel CC SB SRW Lariat
                            Bayham, Ontario, Canada

                            Comment


                            • #15
                              Sewer systems, unless sewage needs to be pumped to an uphill location, are gravity flow, non-pressurized system designed to operate with pipes about half full. This means that they are already vented to the atmosphere. Yes, gasses can and do build up in the sewer system, but my point is that they are already being vented to the atmosphere, whether or not my grey tank drain valve is open. As the system is already properly vented, presumably, my vent stack is not drawing an appreciable amount of gasses from other vents. Even though methane is lighter than air, most of it will exit out other lower vents before it rises to my stack.

                              Let me return to my statement in post 8, that what I'm doing may not be right for everyone, but it is right for me. I have no plans to change how I do things, either.

                              Also from post 8, the real crux of the problem is the cable pull for the valve. None of my three pulls were properly routed or secured. If someone is having trouble getting their valves to close, or are getting spring back when closing the valve, I would first start with how the cable is routed and secured.

                              Another point about eliminating spring back is that the length of cable between the handle and the sheath should then be a constant that can be measured and marked when the valve is closed. If on subsequent operation the cable does not move to this mark, then something is blocking the valve (partially open the valve and flush the tank) or there is a problem with the valve itself.
                              John
                              2018 Momentum 395M
                              2018 Ram 3500 Dually
                              Every day is a Saturday, but with no lawn to mow.

                              Comment

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