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Topic: Fast fresh water tank fill (sort of gravity) (Read 598 times) previous topic - next topic

Fast fresh water tank fill (sort of gravity)

I wanted a faster way to fill the fresh water tank and potentially do gravity, if needed (gravity will work but may be slower).  The gravity fill wasn't a huge requirement, because I have a winterizing valve on the intake of my water pump----I can use that to suck from other sources and fill the tank.

I am one that avoids drilling holes in machines at all costs, and the idea of drilling a hole in a water tank for a new way to fill it seems absurd. So I thought of a few ideas. One idea was to use the vent hose as a fill. But, obviously water going in, means air must go out.....so I was thinking to put a smaller hose inside the 1 1/4" overflow hose. But this would've been a pain in the but.

While I was pondering and looking around at the plumbing, I realized I've been a fool and not considered the gravity tank drain.  On my RV, the tank drain is 1/2" pex that comes right out the bottom of the tank, goes to a ball valve, and then out the bottom of the basement.

To do a temporary trial, I hooked up a garden hose to the drain and filled the tank backwards through the drain. It went much faster and I didn't have to go into the bathroom to open the fill valve.

My permanent mod will involve putting a TEE upstream of the existing tank drain valve. Then I will step up to 3/4 or 1" pex and send it over to the wet bay and put a full flow ball valve over there and a hose hookup. The larger size and lack of elbows should allow much faster tank filling.....and no need to go in the RV when I forget to turn the tank fill on.  Also, I will be able to leave a hose hooked up and not have to put a cap on each time, etc. Much easier evolution.
1998 U270 34'

Re: Fast fresh water tank fill (sort of gravity)

Reply #1 –
Quote from: krush –
It went much faster and I didn't have to go into the bathroom to open the fill valve.
 . . .
and no need to go in the RV when I forget to turn the tank fill on.
It might not have been on the U270, but my U295 has another fill switch on the sewer bay panel. It is *possible* those wires might still be in the wire harness going to that area. Not trivial to get to, but rewarding if it is there. If not, maybe you can route a pair of wires from the other fill switch.
 
Good luck,
 
Trent
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Fast fresh water tank fill (sort of gravity)

Reply #2 –
Trent, there is no fill switch on the u270. It's a manual valve under the bathroom sink.
1998 U270 34'

Re: Fast fresh water tank fill (sort of gravity)

Reply #3 –
Thanks; now I understand your problem. Good luck!
 
Trent
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Fast fresh water tank fill (sort of gravity)

Reply #4 –
Have you taken a look at the water tank where the overflow pipe is attached?  On my 2004 there are 2 threaded holes next to each other.  One is used for the overflow.  I removed the plug fitting in the other hole and drilled a hole in the cover over the tank and then ran a hose, valve and extension.  If no extra hole in tank, mounting a tee does the same thing.  Makes filling super fast. 
Larry Rubin
2004 U295 38' build 6278
2014 Jeep Cherokee

Re: Fast fresh water tank fill (sort of gravity)

Reply #5 –
Quote from: Larry Rubin –
Have you taken a look at the water tank where the overflow pipe is attached?

I've look up in there, and never saw another hole. I'll double check though. The vent/overflow (same thing) is behind the hot water heater and it's very cramped.

Can't put a Tee in the vent line to fill because air must get out....might blow up the tank if filling too fast.

I'll pull the cover on the driver's side and see if there is a hole there.
1998 U270 34'
 

Re: Fast fresh water tank fill (sort of gravity)

Reply #6 –
Quote
Can't put a Tee in the vent line to fill because air must get out....might blow up the tank if filling too fast.

Don't know if it will work but it might with a large enough tee diameter. 
Hole in tank -> hole size nipple -> expansion fitting to get a larger diameter -> large diameter tee with one open leg up and one open leg horizontal -> overflow attached to tee up leg -> fill attached to tee horizontal leg.  The overflow will have to go up several inches before it starts down to reduce fill water from directly going into the overflow.  The pinch point at the entrance to the tank is still there but maybe the large diameter fittings will allow enough air to pass to fill at a moderate speed interrupted by escaping air bubbles. 

A shut off valve on the fill line will prevent water from coming out that way after you have filled.

(You might find a tee with one leg the size of the existing tank hole and the others larger.  This eliminates the expansion fitting.)
Larry Rubin
2004 U295 38' build 6278
2014 Jeep Cherokee