Change Location of Black Water Tank Flush Nozzle

[howson]

ncitro & Cate&Rob,
Learned something new today--thanks for the discussion.

[ncitro]

ncitro & Cate&Rob,
Learned something new today--thanks for the discussion.

Anytime. Again none of this helps the OP, and I am disappointed it came down this way, but unsurprised. I would be shocked if the tanks do not come to GD with the ports already set in them. That does not mean it should not be different, and better, but it is what it is. When I replaced the fresh tank in my old rig, I found two or three tank supplier, and all either offered with ports or without, but for the volume GD has in tanks, to save the labor I am sure they come already ported.

[JBill9694]

This may open up a whole new can of worms but thinking about which part of the tank it is critical to clean I believe it is outlet. If the nozzle is located at the back (furthest from the outlet) it might not move the material all the way out of the tank and instead would build a little dam. Think about what happens when we hose down a sidewalk or driveway, if we don't continually advance the hose we end up with a line of leaves, twigs, dirt, and whatever else is on the surface. Some water will get through this row but not the solids. Now if the RV is used seasonally this row will have a chance to dry out and harden, make it even harder for the next season material to move over and through it. In time this dam could drastically block the outlet to the point where even the initial draining of the tank is not effective at removing solids.

Now with the nozzle is at the front of the tank, right at the outlet it, will clean that area and make sure that there is a clear path for future initial drainings to carry solids out of the tank. Yes, there may be a film of crud left in the tank away from the outlet and in a seasonal use RV this crud may dry and harden but it is not impacting the initial draining of the tank.

[ThePowells]

This may open up a whole new can of worms but thinking about which part of the tank it is critical to clean I believe it is outlet. If the nozzle is located at the back (furthest from the outlet) it might not move the material all the way out of the tank and instead would build a little dam. Think about what happens when we hose down a sidewalk or driveway, if we don't continually advance the hose we end up with a line of leaves, twigs, dirt, and whatever else is on the surface. Some water will get through this row but not the solids. Now if the RV is used seasonally this row will have a chance to dry out and harden, make it even harder for the next season material to move over and through it. In time this dam could drastically block the outlet to the point where even the initial draining of the tank is not effective at removing solids.

Now with the nozzle is at the front of the tank, right at the outlet it, will clean that area and make sure that there is a clear path for future initial drainings to carry solids out of the tank. Yes, there may be a film of crud left in the tank away from the outlet and in a seasonal use RV this crud may dry and harden but it is not impacting the initial draining of the tank.

Okay, what happens when you try to use a weak stream and push against a wall? This what is happening in my case. Their isn't a stream but more like the mist or fog setting on a garden sprayer.

[howson]

Okay, what happens when you try to use a weak stream and push against a wall? This what is happening in my case. Their isn't a stream but more like the mist or fog setting on a garden sprayer.

Jerry,
Back in post 31 (I had to re-read this thread!) there was a mention of determining the water pressure in the line hooked up to the flush. Was there ever a reading obtained?

As documented extensively here, the system is a simple one so testing should also be easy. I'm treading into territory where I'm bound to make a mistake, so hopefully Cate&Rob can confirm (or correct/add to) the steps below:

1) Start with the a water line hooked up but with it shutoff just past a pressure gauge (so there's a starting measurement with no flow).

2) Turn the shutoff to "on"--what's the pressure gauge reading now?

a) If it's at or near the original reading, there's a restriction somewhere in the system. Valve? Kinked line? Clogged sprayer? It will take some troubleshooting to isolate.
b) Pressure drops significantly, but there's little to no flow means the water source (pressure/volume) is poor.

I'd be happy to hook up a pressure gauge and volume meter to compare numbers if you're interested. I'm sure others here can do the same, too, as many of us already have these items in our plumbing kits.

Let me know...

Howard

[Cate&Rob]

Attached is a picture of a black tank flush "nozzle" (taken by Brian Country Campers at a recent factory tech training session for moderators of this forum) This picture has been posted somewhere on another thread. A picture taken through the gate valve opening of a new tank. In this case, the flush nozzle is spin welded into the far end of the tank. (Note the debris in the tank from drilling the toilet pipe and vent access holes.)

As you can see, this is hardly a directed flow device and would quite likely result in a general "mist" of water as mentioned earlier. If this were a focussed jet of water and if it were directed at the gate valve, this might help . . . but regardless of where in the tank this flush is located, it is never going to spray down the interior of the tank as many envision. It is simply a way to introduce a generous amount of water to keep things dissolving and flowing as discussed earlier in this thread.

Rob

[howson]

Cate&Rob ,

That nozzle doesn't appear to be any of the three tested in the linked video below. I found it interesting that the "Tornado" did so poorly at 40psi, and the difference between the Camco and Valterra was so dramatic.

Edit: Re-reading this thread I see you mentioned in post 41 that the sprayer is from B&B, and in the linked document provided the part is a "ABS Tank Spray Head" part # 571 or "Rotomolded Tank Spray Head" part #631.

[ThePowells]

Jerry,
Back in post 31 (I had to re-read this thread!) there was a mention of determining the water pressure in the line hooked up to the flush. Was there ever a reading obtained?

As documented extensively here, the system is a simple one so testing should also be easy. I'm treading into territory where I'm bound to make a mistake, so hopefully Cate&Rob can confirm (or correct/add to) the steps below:

1) Start with the a water line hooked up but with it shutoff just past a pressure gauge (so there's a starting measurement with no flow).

2) Turn the shutoff to "on"--what's the pressure gauge reading now?

a) If it's at or near the original reading, there's a restriction somewhere in the system. Valve? Kinked line? Clogged sprayer? It will take some troubleshooting to isolate.
b) Pressure drops significantly, but there's little to no flow means the water source (pressure/volume) is poor.

I'd be happy to hook up a pressure gauge and volume meter to compare numbers if you're interested. I'm sure others here can do the same, too, as many of us already have these items in our plumbing kits.

Let me know...

Howard

Nope, not yet. My flush line hose goes, starting at the manifold where out tank is, thru 1 inch PVC for 30 feet in a straight line, to a freeze proof hose bib w/ the 3/4 valve and then 25 feet of 3/4 water hose to the connection. My pump kicks in @ 50 PSI and off @ 56. When I am flushing, the pump does cycle, so I know that I am getting at least 50 PSI to the connection. When I get back in there and can look, I may give serious consideration to drilling out the center of that thing they call a sprayer. I think that my best solution may be adding a clean out just above the where the poop goes in and using a higher pressure wand periodically. Hopefully in a couple of weeks, this will be much less of a headache when I get both tanks bypassed.

[JBill9694]

Nope, not yet. My flush line hose goes, starting at the manifold where out tank is, thru 1 inch PVC for 30 feet in a straight line, to a freeze proof hose bib w/ the 3/4 valve and then 25 feet of 3/4 water hose to the connection. My pump kicks in @ 50 PSI and off @ 56. When I am flushing, the pump does cycle, so I know that I am getting at least 50 PSI to the connection. When I get back in there and can look, I may give serious consideration to drilling out the center of that thing they call a sprayer. I think that my best solution may be adding a clean out just above the where the poop goes in and using a higher pressure wand periodically. Hopefully in a couple of weeks, this will be much less of a headache when I get both tanks bypassed.

Instead of adding a cleanout to the top of the tank, I know of others who have just inserted a home made (PVC) wand down the toilet. Just be sure that you turn the valve off before you bring the wand back up. It reads like your on a well with relatively low pressure, are you thinking about running the water through a pressure washer?

[ThePowells]

Instead of adding a cleanout to the top of the tank, I know of others who have just inserted a home made (PVC) wand down the toilet. Just be sure that you turn the valve off before you bring the wand back up. It reads like your on a well with relatively low pressure, are you thinking about running the water through a pressure washer?

Actually I have already added a cleanout where the vent comes out of the black tank and I can remove the cap on top and can remove the plug and can get a wand down into the black tank and spray towards the outlet. I just was thinking about the possibility but realize that with flush attachment in the tank that we have, more pressure it probably a moot point. howson I put the pressure regulator on the line today. 60 PSI static and 35 at full flow.

[Popga]

The BW tank in my Solitude is leaking and will need to be replaced. Grand Design installed the back flush nozzle on the lower end of the tank just above the 3" dump outlet. The flush nozzle should be installed on the opposite (upper) end of the tank so the flushing water can sweep solids/paper toward the dump opening, not away from it. This explains why I can never really get the tank discharge to clear when I dump and back flush the tank.

My dealer will be ordering a new tank from GD sometime soon. I am asking someone at Grand Design to ensure my replacement tank has the back flush fitting mounted on the tank end opposite the discharge opening. I will happily provide the extra 1/2" tubing for the dealer tech.

howson

This is an older thread, but I wanted to post a reply now that I have some more knowledge on the subject.

Because I was not paying attention while flushing my black water tank, I blew the tank up...Twice!

I will complete a thread on those replacements and what I learned eventually.

After reading this thread, changing the the flush out nozzle to the "upstream" side, away for the discharge made perfect sense. Push the poo out. That's what I did for my first tank replacement. What I noticed over the year, was it did not help at all. In fact, I was worse. The nozzle failed to clean up the tanks in the area away from the drain and did not push anything out.

When I destroyed that tank and had to replace it, I moved the nozzle back to its original position near the discharge. It works better. Shooting the water to the back side and letting it drain down to the discharge actually does a better job of cleaning the tank.

Sometimes they actually do things right! Even when it intuitively makes no sense...

Cheers to my last tank replacement. If I do it again, I'll be hanging up my keys.

Erik