how do you fill your water tank?

[jostby]

I recently bought a '20 303RLS with what's supposed to be a 54 gallon fresh water tank. Took it on its maiden voyage last weekend and I'm pretty sure I must have only filled it half full even though the indicator said full.
The salesperson said to fill it until it comes out of the overfill. The manual says to only put in capacity as stated and to NOT overfill it (5 gallon pail at a time maybe?) We were only out a couple days with only 1 short on/off type shower and only had about 2 gallons that drained when we got home (and it said LOW the last day). It said 1/3 tank almost immediately after we first got to our camp spot.
Has anyone cut some sort of access hole to see tank level? Do you fill it slowly after it reaches 2/3 full until it burps out the vent? What works for other "dry" campers?
Our last camper had a 40 gallon tank and would last us over a week under similar conditions. Thanks for any help,
Jeff

[Cate&Rob]

jostby
Hi Jeff,

The panel indicator lights are notorious for being wrong. The overflow is there for telling you when the tank is full. I would invest in a meter for your water hose. Empty the water tank and fill it until it overflows. Your hose meter will tell you how much water that is.

Rob

[Retgw2]

I recently bought a '20 303RLS with what's supposed to be a 54 gallon fresh water tank. Took it on its maiden voyage last weekend and I'm pretty sure I must have only filled it half full even though the indicator said full.
The salesperson said to fill it until it comes out of the overfill. The manual says to only put in capacity as stated and to NOT overfill it (5 gallon pail at a time maybe?) We were only out a couple days with only 1 short on/off type shower and only had about 2 gallons that drained when we got home (and it said LOW the last day). It said 1/3 tank almost immediately after we first got to our camp spot.
Has anyone cut some sort of access hole to see tank level? Do you fill it slowly after it reaches 2/3 full until it burps out the vent? What works for other "dry" campers?
Our last camper had a 40 gallon tank and would last us over a week under similar conditions. Thanks for any help,
Jeff

Quite a few folks have reported that by time they reach a destination their fresh water tank is nearly empty even though is was filled at the beginning of their journey. I'm not sure is this is still happening with the newer models, but the culprit seems to be caused by a siphoning action occurring via the overfill tube while traveling. The easy fix to this is to add a shut off valve to the bottom of the overfill tube, like a sharkbite valve fitting that can be found at the big box stores. It is just important to remember to only shut it off while traveling and make sure it is fully open while filling the freshwater tank or pumping water from the tank.

[ncitro]

Quite a few folks have reported that by time they reach a destination their fresh water tank is nearly empty even though is was filled at the beginning of their journey. I'm not sure is this is still happening with the newer models, but the culprit seems to be caused by a siphoning action occurring via the overfill tube while traveling. The easy fix to this is to add a shut off valve to the bottom of the overfill tube, like a sharkbite valve fitting that can be found at the big box stores. It is just important to remember to only shut it off while traveling and make sure it is fully open while filling the freshwater tank or pumping water from the tank.

I second this. I found before I installed the valve I could see water flowing out of the overflow when I would go around banked curves. Just remember to open it.

[Guest]

Quite a few folks have reported that by time they reach a destination their fresh water tank is nearly empty even though is was filled at the beginning of their journey. I'm not sure is this is still happening with the newer models, but the culprit seems to be caused by a siphoning action occurring via the overfill tube while traveling. The easy fix to this is to add a shut off valve to the bottom of the overfill tube, like a sharkbite valve fitting that can be found at the big box stores. It is just important to remember to only shut it off while traveling and make sure it is fully open while filling the freshwater tank or pumping water from the tank.

I believe its more slosh rather than siphoning. I also attached a Tee on the overflow and a valve below this, and am seriously thinking attaching a half inch line from the Tee (currently capped off) to the vent on the gravity fill on my Imagine.

Jim

[Guest]

Pictures of Tee (intended to connect to gravity fill) and the overflow shut off valve. Very important to open this valve when filling the tank or when the pump is turned on, or tank damage is likely.

Once the vent line is connected to the Tee, there will be no risk to tank damage if the valve is accidentally left closed while filling or while running the pump.

Jim

[ncitro]

I believe its more slosh rather than siphoning. I also attached a Tee on the overflow and a valve below this, and am seriously thinking attaching a half inch line from the Tee (currently capped off) to the vent on the gravity fill on my Imagine.

Jim

Slosh is my guess too. I have tried a few things to automate the valve with no luck (I have a terrible memory). I purchased the check valve discussed in "the other place", but have not tried that yet. I wish they had run the vent line to the roof lol. Would solve all the issues.

[boyscout]

It is just important to remember to only shut it off while traveling and make sure it is fully open while filling the freshwater tank or pumping water from the tank.

jostby this can't be emphasized too much. Another way to say it is that the valve should only be closed while you are on the road, and open at ALL other times. A warning taped over your landing gear controller might be a good idea... you can't use your landing gear to unhook until you've opened that valve.

Another consideration alerted by OffToHavasu is that if your trip involves significant changes in elevation it would be wise to stop at intervals to open the valve to equalize pressure.

The overflow is there for a reason; having it closed when it needs to be open could be very expensive.

That said, a 3/4" Sharkbite valve installed on the blue PEX pipe of the overflow system will probably resolve the problem you've seen; a thirty-second install.

https://www.homedepot.com/p/SharkBit...00LF/202270643

Good luck.

[Cate&Rob]

The open/close of the tank vent could be changed from a manual valve to a 12V signal with a solenoid valve (if someone wanted to do this)

I use the attached valve on my city water feed. It is controlled by the electric water heater switch. When we leave the trailer we turn off the water heater and this also shuts off the city water supply. (We were really bad at always remembering to walk around back and turn off the water faucet when we leave the trailer)

So . . . how best to control the tank vent? One idea would be a limit switch on the landing gear. If the landing gear is down, the trailer is stationary and the tank vent is open. If the landing gear is up, the trailer is (or can be) moving and the vent is closed. This only works if you never use water from the tank or fill the tank when hooked to the truck.

Another idea would be to power the tank vent whenever the water pump is turned on. This covers using water but does not cover filling the tank. A second manual switch beside the fill location could cover opening the vent when filling, but it would not be automatic. Diodes would be involved in this plan because you would not want to back feed the water pump with this second switch.

Just some random ideas . . .

Rob

[howson]

Just some random ideas . . .

I'll see your random ideas and raise you one.

How about a sensor that if water is flowing (in or out of the tank) the valve is opened. No movement of water, valve is closed.

Bonus material: loss of 12v power or battery is low? Valve fails open.

[Cate&Rob]

I'll see your random ideas and raise you one.

How about a sensor that if water is flowing (in or out of the tank) the valve is opened. No movement of water, valve is closed.

Bonus material: loss of 12v power or battery is low? Valve fails open.

Good ideas! Lots of flow switches on Amazon. Tankless water heaters use these. Powering to close the valve rather than open it (fail open) will take a little thought . . .

[ncitro]

Good ideas! Lots of flow switches on Amazon. Tankless water heaters use these. Powering to close the valve rather than open it (fail open) will take a little thought . . .

I am liking these. Double switch might be good so you could vent it at altitude as suggested. We frequently stop for the night and stay hooked up, so that would be needed anyway.

I am going to be pulling the back half of the coroplast at some point to look at my bunkhouse heating duct, and plan to work on improving this then. I have not looked at the tank yet, is the water connection 3/4" pex same as the vent, or 1/2"?

[ncitro]

The open/close of the tank vent could be changed from a manual valve to a 12V signal with a solenoid valve (if someone wanted to do this)

I use the attached valve on my city water feed. It is controlled by the electric water heater switch. When we leave the trailer we turn off the water heater and this also shuts off the city water supply. (We were really bad at always remembering to walk around back and turn off the water faucet when we leave the trailer)

Rob

Probably starting to be a bit of a hijack, but I assume you placed this somewhere in the manifold after the split for filling the tank? Otherwise you would need to turn on the electric water heater to fill your fresh tank correct?

[Guest]

jostby this can't be emphasized too much. Another way to say it is that the valve should only be closed while you are on the road, and open at ALL other times. A warning taped over your landing gear controller might be a good idea... you can't use your landing gear to unhook until you've opened that valve.

Another consideration alerted by OffToHavasu is that if your trip involves significant changes in elevation it would be wise to stop at intervals to open the valve to equalize pressure.

The overflow is there for a reason; having it closed when it needs to be open could be very expensive.

That said, a 3/4" Sharkbite valve installed on the blue PEX pipe of the overflow system will probably resolve the problem you've seen; a thirty-second install.

https://www.homedepot.com/p/SharkBit...00LF/202270643

Good luck.

This is why I want to install a vent line. I can turn off the valve for travel to prevent water loss from slosh and still protect the tank under virtually all conditions,

Jim

[Canyonlight]

I recently bought a '20 303RLS with what's supposed to be a 54 gallon fresh water tank. Took it on its maiden voyage last weekend and I'm pretty sure I must have only filled it half full even though the indicator said full.
The salesperson said to fill it until it comes out of the overfill. The manual says to only put in capacity as stated and to NOT overfill it (5 gallon pail at a time maybe?) We were only out a couple days with only 1 short on/off type shower and only had about 2 gallons that drained when we got home (and it said LOW the last day). It said 1/3 tank almost immediately after we first got to our camp spot.
Has anyone cut some sort of access hole to see tank level? Do you fill it slowly after it reaches 2/3 full until it burps out the vent? What works for other "dry" campers?
Our last camper had a 40 gallon tank and would last us over a week under similar conditions. Thanks for any help,
Jeff

In addition to all the feedback shared, here are some things we have learned with our 54 gallon fresh tank on our 303. We can fill several more gallons into the tank after the gauge reads full until water comes out of the blue overfill. We mainly dry camp and where we use the campground shower facilities for this purpose, our tank will continue to read full for a few days when we use water for just flushing the toilet, brushing teeth, doing dishes etc.

Also consider this, I do not know where the fresh tank monitor probes are located (if one of our technical folks know this would be good to learn and share here) but if the RV (thus the tank) is not level, that could easily impact gauge readings vs actual tank load of water. When you think about a fairly wide and long container vs depth just doing a test with a cake pan and one can see where tilting the pan just abit will impact water levels from one end to the other. Sure one end would be near the top but the other end could be near the bottom.

All this said, I would be curious how level your RV was when you filled the tank. Also knowing how much more water you can fill after the gauge reads full using the meter ads suggested by Rob would be interesting. You may be surprised that it could add up to several gallons.

Lastly on our 303 when tank tank begins to read 1/3 left we may have close to 1/2 or more of a tank just because of how the probes are placed in the tank. It takes some time to go to reading empty at which point there are several gallons left. We have used water as noted above for a couple to a few days and still have a few gallons of water drain from the tank when we pull the lever to empty.

Dan