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Old 08-06-2015, 02:53 PM   #21
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Originally Posted by Dave Tremont View Post
That could be my issue also. that could also explain why the drain will allow the tank to empty as it would not have a screen on it.
That was not the case for me. My tank only has the one outlet. The drain is in line prior to the pump. I would get a drip here and there when I would open the drain, but it took days to get most of the water out of the tank with the drain open, until i cleared it. Now the FW is empty by the time I get home from most trips

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Old 08-07-2015, 08:55 AM   #22
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Tank Plumbing Mysteries Solved!

Okay, so after thinking about it for a long time, I decided to just figure all this out once and for all. I started a new thread on the subject: http://www.jaycoowners.com/forums/f3...tly-29665.html

For reference, my trailer is a 2014 Jay Flight 28 BHBE. My trailer has 86 gallons fresh water capacity (2-40 gal tanks, and the HWH). Since my trailer is completely open on the bottom, everything is relatively easy to see and trace.

The tanks are plumbed as follows: Each tank has a drain in the absolute bottom of the tank that flows to two 1/2 turn plastic valves labeled on the outside skirting of the trailer as a "Low Point Drain". Teed into the drain line from the rearward tank is the water pump pickup. This is all on the curb-side of the trailer.

On the street-side of the tanks, there is a 1.5" (?) equalization hose that is tapped into the side of each tank. This hose simply runs from one tank to the other and is there so that the tanks will fill "equally".

At the top of the tanks on the street side, there are two 1/2" (?) hoses to equalize air between the tanks; they also just run from one tank to another. At the top of the forward tank only are two air vent hoses that route behind the steps and allow air to enter and escape as the tank is filled or emptied.

Sorry about the low-light conditions of the pictures, I did this at about 9:00 at night after loading out my trailer for a trip.

This is from the street-side, looking at the rearward tank. You can see where the tank drain is tapped on the far left, and the line you see that looks like it's going into the propane block (teed between the tank drain and the tee for the drain valve) is the water pump pickup line, it goes straight up to the pump which is under the sink. You can see the rearward drain valve in the upper right foreground.

Here you can see the forward tank drain, and the forward tank drain valve.

This is the water equalization hose on the street side of the tanks.

These are the air equalization hoses (also on the street side) between the two tanks.

This is back on the curb-side from under the stairs. These are the two air vent hoses tapped into the top of the forward tank.

The fresh water gravity fill is up on the curb-side of the trailer above all this and goes into the top of the tank like normal, with it's standard vent line.

So, there you have it. Mystery solved, sort of. This is how it's plumbed on my trailer, as they say, YMMV.

The one big question I STILL have is this: Because of the location of the pump pickup line (teed into the primary tank's drain line), the pump should always be able to pick up water if there is water in the tanks that can be drained.

However, this is not the case. The pump will stop pulling water LONG before the tanks stop draining. And not just one drain, but both drains, and more importantly, the rearward drain where the pump pickup line is plumbed. How can this be?

The only thing I can figure is that there is not enough pressure? The pump is pulling more water than can be drained?

I have some mod ideas brewing here to make all this better ...


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Old 08-08-2015, 11:10 AM   #23
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Thanks for all those photos.
Your set-up is quite a bit different than mine, but also some similarities.
My FW pump draw also comes from the drain lines. The only thing that I can figure is that your pump is actually creating suction, whereas your drains are just gravity feed. That might be the difference. The FW tanks are very long and wide, but not really very deep. With the pump actually sucking water, it could be that it is pulling enough that it is creating a vortex (bathroom tub spiral) above the inlet and sucking both water and air. However, this is just a guess.

Look at the math: You have 2 40 gallon tanks. So for one tank, at full capacity you have 40 gallons. You also said that you have 16 gallons left when you can't get anything more to go through your FW pump. Divided by 2 tanks, that is 8 gallons per tank. Eight gallons is 1/5 of the 40 gallon capacity. If your tank is 8 inches tall (this is just a guess) then when you have only 8 gallons left, it is taking up the bottom 1.5 inches of your tank. 1/5 of 8 inches is 1 3/8 inches. That's not a whole lot of depth of water for your pump to suck from and it could be sucking in some air as well. And all this is assuming that the bottom of your tank is perfectly level. From your photo, I think I see 3 metal straps holding your tanks. I don't know if you took the photos when the FW tanks were full or empty. My tanks had the same 3 straps and they were bulging considerably between those straps when the tanks were full. So it is possible you may have an amount of water that never drains from your tanks or is available as fresh water to your pump. I added 2 additional steel straps to each tank between the 3 that were already there. No more sagging.
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Old 08-08-2015, 03:40 PM   #24
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Dewey, you have hit on the most likely cause of the issue.

The water pump does create suction and is self priming, which is why all valves for bypass must be closed. The water draining out of both tanks will inevitably have a vortex created when the water in the tank gets to a low enough level and the water pump is pulling/sucking the water. When this happens air is pulled through the vortex. Even a small amount of air will disrupt the suction ability of the pump. With the two tanks and the equalization hoses between the two tanks, plus the overflow lines, it is very easy to have a lot of air in the tanks for the vortex to be created.

A piece of advise which can help the situation while out camping is fairly simple. We know these rigs are supposed to be level for proper operation of the refrigerator. However, they do not have to be perfectly level. Reduce or increase the tongue height by a half bubble on a leveling gauge. This will still allow for proper operation of the refer and the standing water in the tanks will shift to either the front or rear low point drain/pick up. You can also shift the left/right level to one side or the other using the stabilizer jacks (I am not saying to begin lifting/jacking the trailer with the stabilizers) i.e., snug one side up by a half turn or full turn and loosen the opposite side by the same amount.
This shift in level does not have to be enough to be noticed by the occupants, but it will be enough for the water.
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Old 08-10-2015, 08:09 AM   #25
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In the post above, my tanks had 25 gallons in them, just for reference.

I'm thinking it might be better to isolate the second tank through the equalization hose. If I could put some kind of valve in that line, then I could use only the capacity I truly need most of the time, and I could open the valve when I need the extra capacity.


2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)

Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!
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