What are these for?

[CoChris]

Should there be a cover for it?

Some trailer have a problem with syphoning water out of the tank when traveling and will put a cover/cap/plug on the over flow to prevent the syphoning when traveling. If you do that, be sure to remove the cap/plug before filling or using water from the fresh tank.

Chris

[Flleek77]

Thank you! Great information!

[IBEW Sparky]

Some trailer have a problem with syphoning water out of the tank when traveling and will put a cover/cap/plug on the over flow to prevent the syphoning when traveling. If you do that, be sure to remove the cap/plug before filling or using water from the fresh tank.

Chris

That is exactly why I put the ball valve on mine. When I removed the dump valve from the bottom of the tank I could see up inside the tank and took some pictures and measurements. Everyone says that overflow pipe comes out the top side of the tank but it doesn't, it actually comes out the side of the tank as close to the top as possible. The tank is approximately 8" tall and the bottom of the overflow port is about 2" down from the top of the tank.... this could result in a significant amount of water loss while traveling. Looking at other threads on here for resolutions I found that others had installed a "T" fitting and extended the overflow pipe to the front propane compartment and then up a few feet so the water would not flow out . I tried that method first but was unsuccessful because it created a long "pipe trap" filled with water that the pump struggled to pull air back through. I fill my tank until water flows out the overflow and then shut my overflow valve preventing water loss while traveling.... ALWAYS gotta remember to open it back up if when you get to your dry camping destination. I did find that I don't need to open it up for a few bathroom stops along the way.

Here's a few pictures looking up through the dump valve threaded port towards the overflow port out the side of the tank.

[Keebler]

@Flleek77

I extended my fresh water tank dump valve and the overflow pipe to a more convenient access point. They are mounted on a bracket that I attached to the rear stabilizer jack.


Attachment 37157


I also reworked the low point drain lines so they are easily accessible.



Attachment 37158

Your work is meticulous!

[Timmer]

Some trailer have a problem with syphoning water out of the tank when traveling and will put a cover/cap/plug on the over flow to prevent the syphoning when traveling. If you do that, be sure to remove the cap/plug before filling or using water from the fresh tank.

Chris

We put a valve on ours for this reason. We were losing 25-30% going down the road.

[Richter]

Should there be a cover for it?

I put a small piece of nylon screen over the opening. Not a “cover”, but something to keep any bugs out. With the screen, it still allows the overflow to work and also allows air to replace the water that is used from the tank. I just wrapped the screen over the end and put a zip-tie around it all to keep it in place.

[IBEW Sparky]

@Keebler

Thanks, I try my best. Lots of years in construction and the old back ain't what it use to be... some of these mods are a necessary evil.

[luvmyrv]

Our brand new Grand Design that we just picked up 3 weeks ago has 2 lengths of that same blue pex right next to the fresh water dump valve. I wonder if they incorporated a 2nd line into the system to separate the overflow from the fresh air intake? Can't figure out why I have 2 lines there.

[Canyonlight]

Our brand new Grand Design that we just picked up 3 weeks ago has 2 lengths of that same blue pex right next to the fresh water dump valve. I wonder if they incorporated a 2nd line into the system to separate the overflow from the fresh air intake? Can't figure out why I have 2 lines there.

That sounds like the design change suggested a few months ago by some fellow GDRV owners who are retired Engineers, to GDRV to prevent the overflow of the fresh water tanks when full.

I would be curious to see the pictures of your 295 as this is the first I have heard of it being in production.

Dan

[luvmyrv]

That sounds like the design change suggested a few months ago by some fellow GDRV owners who are retired Engineers, to GDRV to prevent the overflow of the fresh water tanks when full.

I would be curious to see the pictures of your 295 as this is the first I have heard of it being in production.

Dan

The 295 has been in production since at least 2019....or are you referring to the use of the 2 pex lines I referred to in my post?