Slow Draining Gray Tank

[littleapple]

Just purchased a new Imagine TT and seem to have a problem with the gray tank draining correctly (this trailer only has one gray tank). This is my fourth trailer and my experience draining gray tanks has always been that they drain pretty fast and with enough force to flush out the sewer hose after draining the black tank first. However, this new gray tank drains at about half the volume (when the tank is clear full) that I have experienced with my past trailers (all of the drain plumbing is the same size as on my other trailers). So, I don't get enough flush force/volume to adequately flush out the sewer hose after draining the black tank, and it takes a long time to drain (haven't actually timed it yet) which creates a problem at the dump station when others are in line behind me. The gate valve lever seems to be working correctly. I have an endoscope that I can use with my cell phone, but I can't get it to go past two 90-degree bends to get up to the valve. So, while I will be taking the trailer back to the dealer in a couple of weeks for several warranty items and will mention this issue, I was just wondering if anyone else has experienced this problem with your gray tank(s).

[Second Chance]

There have been problems reported when a cut-out disc (created when the holes for the vents are cut in the tanks) is allowed to fall into the tank and left there. The disc can then make its way to the outlet with the flow of liquids and either partially or completely block the outlet. The fiberoptic scope is a great way to find out whether or not this is the case - too bad you can't get it past the bends. Does the valve handle seem to travel it's full stroke length?

BTW - welcome to the forum and the Grand Design family. You can create a signature block with your RV and tow vehicle information (see mine below). That way you won't have to repeat that information whenever you post or ask a question - and others won't have to ask. You can create a signature by going to:

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Rob

[NB Canada]

Mine doesn’t drain with a big rush either
I noticed this more this year than last though

[stroguy]

Mine is slow as well. I try to get it to full and the wife tells me the sink is ot draining fast. Then it has a good rush for half an empty and then slows considerably.

[littleapple]

Thanks for the welcome! Yes, the valve handle has the same stroke as the black tank.

[Second Chance]

Thanks for the welcome! Yes, the valve handle has the same stroke as the black tank.

It sounds, from what others are saying, that the slowness may be a "feature" of that model. Perhaps your dealer can shed some light when you take it in.

Rob

[Ynot4me2]

On mine, it will start off with a good flow, then at the end it's what I call a never ending trickle. When ever I get a reason to drop the coroplast, I'll investigate the gray tank. Maybe it's on an angle or maybe there's not enough angle on the drain tube.

[FlyStar]

I get the same. Bug rush then the never ending trickle. When it trickles I shut the valve and move on. Not especially patient.

[Second Chance]

On mine, it will start off with a good flow, then at the end it's what I call a never ending trickle. When ever I get a reason to drop the coroplast, I'll investigate the gray tank. Maybe it's on an angle or maybe there's not enough angle on the drain tube.

I get the same. Bug rush then the never ending trickle. When it trickles I shut the valve and move on. Not especially patient.

The gray tanks on our 310 do the same thing. I think it's because they are very wide/flat/shallow tanks (as most are, now). As long as there's several inches of liquid in them, there's enough pressure to drain decently; when it gets down to the dregs, the trickle goes on... I do as @FlyStar does - close the valves and move on.

Rob

[USA in a Chevrolet]

Just purchased a new Imagine TT and seem to have a problem with the gray tank draining correctly (this trailer only has one gray tank). This is my fourth trailer and my experience draining gray tanks has always been that they drain pretty fast and with enough force to flush out the sewer hose after draining the black tank first. However, this new gray tank drains at about half the volume (when the tank is clear full) that I have experienced with my past trailers (all of the drain plumbing is the same size as on my other trailers). So, I don't get enough flush force/volume to adequately flush out the sewer hose after draining the black tank, and it takes a long time to drain (haven't actually timed it yet) which creates a problem at the dump station when others are in line behind me. The gate valve lever seems to be working correctly. I have an endoscope that I can use with my cell phone, but I can't get it to go past two 90-degree bends to get up to the valve. So, while I will be taking the trailer back to the dealer in a couple of weeks for several warranty items and will mention this issue, I was just wondering if anyone else has experienced this problem with your gray tank(s).

One thought worth trying is to go up on the roof, if you are comfortable with that, & use a garden hose to flush out the roof vent. Be sure to leave the grey tank valve open. If the vent pipe fills up it was never connected or is clogged with who knows what. I had this problem with a black tank in a former fifth wheel & I suspected I had filled the tank too far before flushing & the vent was clogged.