Gravity fill mod needed

[Modmike]

Is it possible to fill the fresh water tank using the city water inlet and a valve?

I seem to remember that some cvs have this option. How does it work? Is it just a valve?

Thanks.

[ScottBrownstein]

Originally Posted by Modmike

Is it possible to fill the fresh water tank using the city water inlet and a valve?

I seem to remember that some cvs have this option. How does it work? Is it just a valve?

Thanks.

Yes...and some tubing. My Bounder had such a feature. It is a bypass that goes from the high pressure side of the water pump to the intake side of the water pump. When you have city water hooked up it pressurizes the plumbing system. The pump has a check valve on its output side to hold the system pressure. If you put in a bypass, the city water pressure will go around the pump and fill the tank.

[youroo]

Originally Posted by Modmike

Is it possible to fill the fresh water tank using the city water inlet and a valve?

I seem to remember that some cvs have this option. How does it work? Is it just a valve?

Thanks.

If you have a OSS you only need a Hose to reach the F/W fill opening! Youroo!!

[Modmike]

Originally Posted by ScottBrownstein

Yes...and some tubing. My Bounder had such a feature. It is a bypass that goes from the high pressure side of the water pump to the intake side of the water pump. When you have city water hooked up it pressurizes the plumbing system. The pump has a check valve on its output side to hold the system pressure. If you put in a bypass, the city water pressure will go around the pump and fill the tank.

Brilliant, and easy! Thanks!

Does it also eliminate all of the venting issues? I suspect it will because the gravity fill tube acts as a super vent.

Any downsides to this mod? Why aren't all the RVs plumbed this way?

[Modmike]

Originally Posted by youroo

If you have a OSS you only need a Hose to reach the F/W fill opening! :thumbs: Youroo!!

What is OSS?

[bubbles]

Originally Posted by Modmike

What is OSS?

Outside shower (OSS). And no internal plumbing work involved with this type of setup.

[Modmike]

Originally Posted by bubbles

Outside shower (OSS). And no internal plumbing work involved with this type of setup.

I do have one but don't understand how that would work. Can you elaborate with less acronyms please?

Thanks!

[abjb]

Originally Posted by Modmike

Is it possible to fill the fresh water tank using the city water inlet and a valve?

I seem to remember that some cvs have this option. How does it work? Is it just a valve?

Thanks.

I'm curious, why would you want to?
Sounds like a LOT of work just to avoid cutting a hose to a couple of feet and using a funnel + our pump is in a very hard to reach area.

[Modmike]

Mine is VERY easy to reach and second gravity fill is such a pain, especially with the vent needing burping and then back siphoning.

Definitely doing the mod this aft unless someone can explain the OSS methodology.

[bubbles]

It is assumed you have the outside faucet in your external hookup bay and making a short piece of hose long enough to reach between your fresh water input port and that faucet with the applicable connections (readily available) on the ends and using the outside shower faucet valves to route the water from it to fill the holding tank. Of course I'm just trying to elaborate on the suggested input from someone else. I don't quite understand why you would want to try and do what it sounds like to me. If you have pressure to the city water inlet why not just hook to tank fill port? Confused I am.

[abjb]

Originally Posted by Modmike

Mine is VERY easy to reach and second gravity fill is such a pain, especially with the vent needing burping and then back siphoning.

Definitely doing the mod this aft unless someone can explain the OSS methodology.

It is a true pain, 5 gal at a time and I only had two 5 gal water cans.

[Modmike]

Originally Posted by bubbles

It is assumed you have the outside faucet in your external hookup bay and making a short piece of hose long enough to reach between your fresh water input port and that faucet with the applicable connections (readily available) on the ends and using the outside shower faucet valves to route the water from it to fill the holding tank.

That's what I thought. I have everything I need so I am doing the bypass. If I leave the gravity feed open while I fill it will vent and I will get a full tank. Worse that can happen is that it will overflow through vent.

Woohoo!

[ScottBrownstein]

Originally Posted by Modmike

Brilliant, and easy! Thanks!

Does it also eliminate all of the venting issues? I suspect it will because the gravity fill tube acts as a super vent.

Any downsides to this mod? Why aren't all the RVs plumbed this way?

If you have a gravity feed (that is what the Bounder had) it usually has a small vent behind the same door. However, you are right, if you aren't using the gravity feed it is really a super vent, as long as you take the cap off!!!!

Nice thing about this design is all you have to do is open the bypass, fill the tank and then close it again. No hoses to connect or store.

[Kadiddle]

Similar but slightly different challenge in the FR3s, at least the 2015. Mine did NOT come with a gravity feed for the fresh water tank. Just a separate input that one has to overcome the backflow valve pressure to pretend any sort of gravity feed. For one campground I go to, I needed a way to get water from a jug into the tank. So....

I not only put in a bypass around the pump as discussed above I also set it up so the winterizing/antifreeze hose could be used to pump water from a jug/pail/etc. into the fresh water tank. The former saves having to move the city water hose and the later allows me to pump without having to lift/balance a large vessel for pouring. Note the winterize hose gets sanitized in the spring when I use it to suck in a bleach/water mixture.

[RVnut]

What I have done to feed fresh water from a jug into the tank is I got a regular RV water pump and put 12 foot wires with alligator clips on it and two 4 foot pieces of hose on each end with a male hose connector on the outlet to hook on the fresh water tank connector.. Hook up the wires and away you go.. I carry two ten gallon tanks for back up

[Modmike]

SO it turns out I have no gravity feed. The only to fill the tank is from the fresh water fill which requires a pressurized hose.

No need to modify anything.

Funny thing though, if you overfill, the overflow works perfectly, and then keeps on working, until it empties a quarter of the tank. Never let the overflow go full bore, if you do, break the syphon by opening a tap.

Tank design is crap. Thee must be at least 8 gallons that can never be used because the intakes are 1" off the bottom. Could have installed clunks for crying out loud.

[bubbles]

Originally Posted by Modmike

SO it turns out I have no gravity feed. The only to fill the tank is from the fresh water fill which requires a pressurized hose.

No need to modify anything.

Funny thing though, if you overfill, the overflow works perfectly, and then keeps on working, until it empties a quarter of the tank. Never let the overflow go full bore, if you do, break the syphon by opening a tap.

Tank design is crap. Thee must be at least 8 gallons that can never be used because the intakes are 1" off the bottom. Could have installed clunks for crying out loud.

It's actually the vent for the holding tank but does let you know when the tank is full. If you have room near your tank to add a loop in the vent tube pointing up it should prevent the syphoning from happening. Sometimes though there just isn't enough room to accomplish this. I was confused by what you were wanting to do as I have not heard of any GT's that had a "gravity fill" port for the holding tank but maybe the 2016's had added one.

[KenHwy61]

Originally Posted by Modmike

SO it turns out I have no gravity feed. The only to fill the tank is from the fresh water fill which requires a pressurized hose.

No need to modify anything.

Funny thing though, if you overfill, the overflow works perfectly, and then keeps on working, until it empties a quarter of the tank. Never let the overflow go full bore, if you do, break the syphon by opening a tap.

Tank design is crap. Thee must be at least 8 gallons that can never be used because the intakes are 1" off the bottom. Could have installed clunks for crying out loud.

That is true. I added a second water tank and spent lots of time messing with tanks and water lines and vents. You will never get the rated tank capacity. They don't fill to the top and do leave an inch on the bottom.They also tend to siphon especially when the vent line isn't high enough. To further confuse the matter, the water heater is usually included in the advertised total fresh water capacity but can't be used because once your fresh water tank is empty there is no pump pressure. If have an advertised 50 gallon capacity you probably only have 35 gallons usable water. You can move the tank outlet line to the bottom drain port to get more water. Just use a tee so the drain can still be used.

[clutchd]

I removed my drain from the tank, added a "t" fitting. One end still drains the tank, the other goes to the water pump feed. I get all my water usable. I also used a ball valve instead of a cap for the drain and did the same for the low point drains. Very easy to do

[Modmike]

Originally Posted by bubbles

It's actually the vent for the holding tank but does let you know when the tank is full. If you have room near your tank to add a loop in the vent tube pointing up it should prevent the syphoning from happening. Sometimes though there just isn't enough room to accomplish this. I was confused by what you were wanting to do as I have not heard of any GT's that had a "gravity fill" port for the holding tank but maybe the 2016's had added one.

On my 364 there is a clear overflow tube with a loop attached to the top of the fresh water tank. It WILL siphon if the loop is full of water. Holding tank overflow is in my shower, yuck!

The tank does bulge from the top when full so maybe we are sort off getting rated capacity. I am looking for a slightly bigger tank that will fit through the door but no luck yet. May get up to 75 gallons if lucky, the stock 50 gallon one is ridiculous.