Two Overflow Tubes?

**Dale G** · 03-27-2023, 08:06 AM

I have a 2023 Reflection 337RLS and there are two blue tubes right next to the freshwater holding tank drain valve. I know the front one is the overflow because when I sanitize the tank and fill it up completely water comes out of it when the tank is full. There never is any water that ever comes out of the other tube. Is it a vent for the freshwater tank, or if it is not a vent, what is its purpose? The manual refers to overflow "tubes", as in plural, but water never comes out of the second tube. Does it not have water coming out of it until the tank is REALLY full?

Thanks,
Dale

**Canyonlight** · 03-27-2023, 08:26 AM

Dale - a previous forum member who is a retired Engineer worked with GDRV to design and implement a change to the fresh water tank to prevent water from flowing out of the tank when filled full which many members have expressed concern over for years.

I do recall seeing the design but not a picture of one on a GDRV. I suspect this is what you are referring to. Post a picture/pictures if it works for you to do so.

Dan

**Dale G** · 03-27-2023, 09:53 AM

Originally Posted by Canyonlight

Dale - a previous forum member who is a retired Engineer worked with GDRV to design and implement a change to the fresh water tank to prevent water from flowing out of the tank when filled full which many members have expressed concern over for years.

I do recall seeing the design but not a picture of one on a GDRV. I suspect this is what you are referring to. Post a picture/pictures if it works for you to do so.

Dan

Dan,
Thanks for the response. In the picture, the water comes out of the forward blue tube when the tank is full. Nothing comes out of the back one. I am very quick to shut off the water as soon as there is a sign of water starting to come out.
Thanks,
Dale

**Canyonlight** · 03-27-2023, 10:48 AM

Dale - to add to my original post no problem filling tank until water comes out of the overflow......that's the primary reason it is there. This said, GDRV used to (and maybe still does) in the Owners Manual state to owners/users to monitor the fresh tank gauge and when it indicates full to stop filling. Hmm, most of us here think this is a PYA legal statement to prevent possible issues overfilling the tank and possible issues. The great majority of us long time campers have always relied on the tank overflow as an indicator of full and to promptly stop filling.....long before gauges existed. However, folks can get distracted when filling and this is when possible problems can happen.

What was happening to a number of folks was that the water did not quit flowing out of the overflow thus allowing in some cases several gallons of water to exit the fresh water tank. It became a siphoning effect with a water fall trailing the camper or running all over the campsite....yikes ! The full tank after several minutes became 3/4 or so full......not good especially if dry camping for sometime where fresh water is important. A non-happy camper syndrome can occur !

If you conduct a search on siphon or siphoning I suspect you will be able to read several of the these posts and learn how valuable to new vent tube is to prevent this and glad you have the new design.

Dan

**Dale G** · 03-27-2023, 12:05 PM

Originally Posted by Canyonlight

If you conduct a search on siphon or siphoning I suspect you will be able to read several of the these posts and learn how valuable to new vent tube is to prevent this and glad you have the new design.

Dan

Dan,
So, the extra tube is a vent then. I have actually ordered an inline water meter so I don't have to rely on the overflow tube to tell me when the tank is full. The only time I fill it that full is in the Spring when I am sanitizing the system. I don't like to use the full light on the panel because the water will flow for a number of minutes once the light says it is full, which it is not. Normally I only travel with 5-10 gallons of water in the freshwater tank so we have it if we need it. The new meter will be great for this as well, so I don't have to guess when I have the right amount of water.
Thanks for the info,
Dale

**Canyonlight** · 03-27-2023, 01:03 PM

Originally Posted by Dale G

Dan,
So, the extra tube is a vent then. I have actually ordered an inline water meter so I don't have to rely on the overflow tube to tell me when the tank is full. The only time I fill it that full is in the Spring when I am sanitizing the system. I don't like to use the full light on the panel because the water will flow for a number of minutes once the light says it is full, which it is not. Normally I only travel with 5-10 gallons of water in the freshwater tank so we have it if we need it. The new meter will be great for this as well, so I don't have to guess when I have the right amount of water.
Thanks for the info,
Dale

Dale - I think GDRV techically calls it an "Anti-siphon tube" or something to that effect. It was implemented to production on all models effective about 5/2021.

Details of the research, design, etc. are available on the other GDRV technical forum.

Moderators, I hope it is OK to state this....as the information is valuable to help all owners especially those many with the siphoning challenges experienced over the years.

We also use a water meter at times......was nice initially to confirm that we could actually get 54 gallons of water in our tank as the stated size.

Dan

**LMagelitz** · 03-27-2023, 02:23 PM

Just took a GD factory tour today…should have taken a pic, but the vent/overflow comes out the side of the tank near the top, elbows up above the tank, elbows over, tees down with one pex pipe, then continues a short distance and elbows down with the second pex pipe. Makes sense that would stop a siphon.

**Canyonlight** · 03-27-2023, 03:23 PM

Originally Posted by LMagelitz

Just took a GD factory tour today…should have taken a pic, but the vent/overflow comes out the side of the tank near the top, elbows up above the tank, elbows over, tees down with one pex pipe, then continues a short distance and elbows down with the second pex pipe. Makes sense that would stop a siphon.

Larry - thanks, for sharing this ! The tours are quite informative and enjoyable to take. We learned much when we did one in 2018 as I'm sure you did as well.

Your description is right on and helpful to Dale and others I am sure.

Dan

**Dale G** · 03-27-2023, 05:05 PM

This is all great information and I appreciate the help. We also did the tour back in 2019. At the time we had an Imagine 2670MK, but we had desires to one day get a Reflection 337RLS, so we took the Reflection tour. As it turned out, the 337 was what they were building at the time, so we got to see how our future fifth wheel was made. I think seeing how they made the unit helped with our decision on which fifth wheel, and brand, we wanted.

Thanks again for helping with my question,
Dale