Precept Fresh Water Fill

[SherpaTravels]

Does any Precept 31UL owner know where the fresh water inlet is in the tank?

Our 2015 model has the tank strapped firmly up against the floor of the coach. I have examined the five exposed surfaces of the tank and see no way for fresh water enter to the tank.

There is one fitting on the bottom of the tank near the rear of the tank on the driver side and three fittings for the three overflow drains on the top of the tank near the front on the driver side.

What am I missing?

[Grumpy]

You use the manifold valves in the utility center to switch where the water goes.

[SherpaTravels]

Thanks, Grumpy, but my question was "where is the fresh water inlet in the tank?", not how to fill the tank.

I know the tank has to fill from the top but I cannot how that happens on our 2015 Precept 31UL. The top of the tank is strapped tightly to the floor of the coach.

[Vicr]

It's the same connection as city water. Hook your hose up turn the knobs to what the chart says and fill away.

[Robbbyr]

I don't have a Precept but it wouldn't surprise me if it is plumbed the same way as my rig.

The water fill to my tank is the exact same pipe as the water out on the bottom. When my valves are aligned to fill the tank, water comes into the tank via that pipe. When you align the valves to use the tank/pump, the water flows the opposite direction and exits the tank through the same pipe and into the pump. All determined by the valves.

I have the same three overflow ports and hoses on top.

[SherpaTravels]

Rob,
I think you have come closest to answering my question which was not how to fill the tank, but where is the fill fitting is on the tank. Jayco customer service told me the tank was filled from the top. On my tank I cannot see how that is possible.
I've crawled around the tank and believe my tank has only one fitting on the bottom and the three overflow fittings on the top.
Yours seems to be the same.

[Robbbyr]

A way you can find out for sure, I discovered this myself.

By peering up in one of my exterior compartments I can see my freshwater tank; that bottom inlet fitting; and the three overflow hoses. Perhaps there is a place you can see the same.

Now to winterize my coach I first blow out all my lines with air. To do so I rigged up an air adapter that has male garden hose threads (so as to screw into the city water connection) and on the other end it has a male air quick-disconnect fitting. I can screw this adapter into my city water connection and hook up an air line which I regulate down to about 20-25 psi maximum. I do this to purge the water in my plumbing, I then refill my system with RV antifreeze. Overkill - probably!

But when I have water in my freshwater tank I can align my valves for city tank fill, then turn on the air (as if it were city water coming in) which flows into that bottom line to/from the water tank. It bubbles furiously in the tank as you might imagine, confirming that line is the water inlet. Now doing this is not part of my winterizing routine, I discovered it by accident once not realizing my freshwater tank wasn't completely empty. Now I make sure it is indeed empty before I proceed!

[Grumpy]

Sorry I misunderstood.

As Robbbyr said it's normally filed using the same water line on the bottom that the pump draws from. That is why they use the manifold system to switch the direction of flow.

[SherpaTravels]

Thanks, Grumpy and Rob R.
It's clear to me now that the one fitting on the bottom of the tank is the only fitting attached to the RV plumbing and is used for both filling and for draining.

New question: Have you any idea why there are three overflow tubes? The reason I started looking into how the tank was plumbed was to find a way to stop the water from siphoning out when the tank was filled. Once the siphoning starts it doesn't stop until almost 1/3 of the water is emptied out.

Jayco has a suggested fix for this but I'd appreciate any ideas you have. Thanks.

[Robbbyr]

I was told there are 3 to prevent overpressurizing the tank since full city water pressure can be directed to the tank. As compared to the traditional gravity fill you need more vent capacity than fill!

As far as the siphoning this seems to be an issue across the different models, you are not alone as a Precept owner. Some owners have used valves in the lines, shutting them after filling and opening them before use. I'm considering that myself, but one mistake might result in a ruptured tank.

I am going to research and see if I can find a low-pressure vacuum/pressure relief valve, one that would stop siphoning but allow water to be drawn from the tank without collapsing it. But it would also prevent overpressurizing the tank when filling. I know they make such a device for other applications, just have to see if it could be applied to a RV fresh water system.

What did Jayco suggest?

[SherpaTravels]

Jayco has a document titled, “Breaking the Siphon on a Fresh Water Tank” which they sent me. It says: “To keep the tank from siphoning, remove one of the overflow lines off at the top of the tank, install a 45 degree elbow pointing upwards, and then connect a short piece of the line (4”) to the 45 degree elbow.” The photos in the document make this more clear.

This would not work on my tank as there is no access to the fittings on top of the tank without cutting a hole in the floor of my RV. I called Jayco customer service and found the recommended plan B is to shorten one of the three overflow lines (to a foot or two) and secure it to the bottom of the RV floor. The end of it would not be higher than the top of the tank, but would be close.

I’ve read most of the online solutions but could not understand why the siphoning would continue after the water level dropped below the overflow intakes. Jayco customer service explained that the seemingly rigid tank collapses because of the vacuum created by the siphoning keeping the overflow fittings down against the water. Who would have thought?

[Robbbyr]

Thanks for the info. Hope you can get your siphoning resolved.

I can get to the fittings on mine, might have to try that fix.

[Rje]

We can’t get water in our fresh tank.