Fresh Water Gauge question

DreamQst · 06-12-2012, 08:22 AM

We have recently purchased a Raptor 30FS and while camping over Memorial Day weekend we filled the fresh water tank to 1/3 full (or so the gauge said) which should have been about 30 gals. Pump was pumping as much air as water and would not build enough pressure to shut off. After doing some general trouble shooting we decided to put some more water in it. Filled it to the 2/3 light and everything worked fine - until it got back down under the 2/3 make. Then the problem came back.
Talked to the dealer upon our return (they didn't return our call while we were camping - even though we called them first thing Friday morning) and we desided to fill it back to the 2/3 line at home, run the water until it started pumping air and then drain the tank to see how much was left.
Did that and didn't run it to the point that the was pumping a lot of air but the pump was not shutting off with the water turned off. When I drained the tank, I got about 7 or 8 gallons out.
So it seems that the gauge is quite a bit off. Anyone else have similar problems? Any quick fixes or recommendations?

geo · 06-12-2012, 09:36 AM

DreamQst -

I am going out on a limb here trying to help. The specs say you have an 86 gallon fresh water capacity and a 6 gallon water heater. There is probably 4 or 5 gallons in the water lines, so I would guess that your fresh water tank is 75 gallons. So, a third should be 25 gallons. But you say that you had problems when the tank was just below the 2/3 (50 gallon) mark. My guess would be that the fresh water pick-up tube is bent, broken, damaged, etc. In other words, when you get to that 50 gallon mark, inside the tank, the plastic pipe that pulls the water from the bottom of the tank probably has a hole in it. Since you still pulled water, along with air, my guess would center around a hole in the pickup tube around the 2/3 fill mark.

The problem with trying to drain the tank is that the drain is probably located above the bottom of the tank. I have a 50 gallon tank in my Alpine. It has a "rounded bottom" such that I would guess there is 8 to 10 gallons capacity below the fresh water drain! To attempt to totally drain my tank, I have to park the Alpine on a slope with the fresh water drain tube downhill.

Now, as far as the guage is concerned. The sensors for the guage are located on the side of the tank near the inlet, vent, and fresh water pickup tube. The Empty sensor is located above the location of the drain tube, so if your tank is "round bottomed" as mine is, you probably still have 8 to 12 gallons of water even when the tank is empty!

With air in the lines, you are probably never going to build enough pressure for the pump pressure shut-off switch to activate. You probably also have a pressure reservoir on the system that holds a gallon or two. With the "mixed in air" you can't get the pressure reservoir built up to activate the shut-off switch.

However, all the above is speculation from the information given. All disclaimers apply. But it might be a place to start looking.

Ron

therink · 06-12-2012, 01:46 PM

I'll throw this one in the mix: It could be that the wiring from the various levels contacts on the tanks are crossed or miswired on the display. Whereas 2/3 is really 1/3. You could try swapping the wires behind the gauge board. It would save a trip to the dealer, if that is the case.

geo · 06-12-2012, 03:19 PM

But Steve, that doesn't explain the air in the water pickup line. Since the air "goes away" above 2/3, that seems to say that the sensors are OK.

Ron

therink · 06-12-2012, 03:34 PM

Quote:

Originally Posted by geo

But Steve, that doesn't explain the air in the water pickup line. Since the air "goes away" above 2/3, that seems to say that the sensors are OK.

Ron

It sounds like one of two different possibilities. 1) The suction pick up line in the tank is too short or the gauge is mis wired. Have you tried emptying the tank, then watching the gauge as you fill it? I Once you rule out gauge problems, then you can focus on the pick up line. If under warranty, I have found it much easier to tell the dealer what the problem is than wait for them to diagnose it.
Good luck.

**JRTJH** · 06-12-2012, 04:29 PM

Just an "Idle thought" from an "old fart" (another thread but some good reading).....

If the water pump worked before this problem, (I'm sure the dealer checked it out) it probably isn't the tank sensors. My guess would be that there is a loose connection somewhere in the fresh water supply line. My first check would be the actual water pump hose connection. You may have a "plug in" fitting on the water pump with a slide lever to lock it in place. There is an O ring on that elbow. It may not be well seated or not completely locked in place or the screw clamp holding the hose to that fitting may have worked loose. The pump pulls water from the tank and the more water in the tank, the less "distance" it has to pull, so if the tank is nearly full, there'd be less vaccuum required to suck water to the pump.... If the tank is nearer to empty, water would have to be drawn further by that vaccuum before the pump could purge the air.

My guess would be the draw side of the water pump has a loose connection. I hope you get it figured out...

As therink suggested, empty your fresh water tank, hold the check button on your system monitor panel as you fill the tank and watch the sequence in which the lights illuminate. If they are wired correctly, they will light from empty to 1/3-2/3-full in the proper order. If incorrectly wired, they will light in the order they're connected.

Good luck

f6bits · 06-12-2012, 04:40 PM

Hopefully you can eyeball the freshwater tank. That should tell you a lot about the situation.

That’s next on my list of “things to explore” on my trailer. Mine’s working properly, but I really want a good look at how the hoses and sensors are situated.

geo · 06-13-2012, 04:55 AM

Scott -

I can post a picture of what it looks like on an Alpine. I would think it would be similar.

Ron

f6bits · 06-13-2012, 05:30 AM

Please don’t. I need an excuse to tinker and explore.

Quote:

Originally Posted by geo

Scott -

I can post a picture of what it looks like on an Alpine. I would think it would be similar.

Ron

azlee56 · 06-13-2012, 05:36 AM

send me the picture pretty please. It should be close to the Montana.

bennydog · 06-13-2012, 08:31 AM

I've always been frustrated with the 1/3 2/3 Full tank gauges in the trailer. My fresh tank is 60 gallons and there is a lot of water between 20 and 40 gallons. I was inside an Airstream and noted that their tank gauges were in "percent of".
While I have not yet undertaken the project it's on this years list.

Link included.

http://www.rvgauge.com/products/model_709ARVC.shtml

geo · 06-13-2012, 08:52 AM

Scott! Do not look at this posting!!!

Bennydog -

Are you sure you have a 60 gallon tank? Does the specs from Keystone say that you have "Fresh Water: 60 gallons"?

If it is the latter, subtract the gallons of the hot water heater, then another 4 gallons or so for the Pex piping and pressure vessel. That will give you the fresh water tank size.

For example: My Alpine has the specs of "Fresh Water: 66 gallons". I have a 12 gallon water heater. Throw the 4 gallons in for the Pex pipes and pressure vessel. That adds up to 16, and subtract that from 66. That leaves 50 gallons. I have physically seen my fresh water tank, and it has molded into the plastic: "50 Gallons".

So, if you have a 6 gallon hot water tank, plus 4 in the pipes, you probably have a 50 gallon fresh water tank also. But on top of that, if your tank is like mine, it has a rounded bottom that is below the "Empty" sensor and below the fresh water drain. I have guessed and wondered, but just say there is 5 gallons at the bottom. That means that "Full" is 50 gallons, 2/3 full is 35 gallons, 1/3 full is 20 gallons, and Empty means you are on the last 5.

In the FW_side.jpg, you can see the wires leading to the tank sensors behind the ringed fresh water fill hose. The vent hose is at the top, and the pickup Pex pipe descends behind the flexible furnace duct. In the Fresh_Water_Tank.jpg, you can see the lousy piece of R-7 insulation with the rounded bottom of the fresh water tank right above it. On the Drain.jpg, you can see that the drain is above the lowest point of the tank.

No Canadian Math or Canadian Math Conversions were used in the above estimates!

Hope this helps.

Ron

azlee56 · 06-13-2012, 09:01 AM

thanks for posting this. Now I see even more need to put some bleach in my freshwater tank as it sits. It never really is empty is it? (I am not parking it on some hill. lol). Unless the water pump literally can pump it all up and out like I first thought. At any rate, it makes me see the need to really take care of the tank.

azlee56 · 06-13-2012, 09:04 AM

LOL Ron. I don't have a clue of what you are referring to with the math.

(was rereading and caught the last)

geo · 06-13-2012, 10:07 AM

Azlee56 -

As I have noted in another post (describing installing tank heaters on the Fresh Water tank), there appears to be "sediment" on the bottom of my fresh water tank. This "sediment" also appears not to be "sand colored" but either white or beige. I know it is not from my filling it with water as I have a gradational 5 micron to 1 micron filter that all incoming water passes. I believe it is probably from the construction of the Alpine, and that it probably is a combination of plastic cuttings from drilling the sensors in and sawdust from construction. I get the feeling that a lot of "items" are left "open" around the Keystone manufacturing/assembly facility.

So, this does indicate that one wants to sanitize the fresh water system. And if any of this sediment is wood dust, I would say sanitizing the fresh water system at least once a year is a good idea. But this "sediment" could possibly present another problem. If one were to run very low on fresh water and draw the fresh water tank down to near empty, this sediment would be drawn towards the pick-up tube. I would suppose the pick-up tube has some manner of screen on its inlet. So this sediment could clog that screen and shut off the flow of water. But what if that pick-up tube was located, say, at the same level as the drain tube of the fresh water tank? That means there is some 5 or so gallons of water that would never be picked up or removed by pumping. One would have to park on a hill or jack the RV up to drain this remaining water.

Yup, sanitizing the fresh water system is definitely always a good idea.

Ron

azlee56 · 06-13-2012, 10:18 AM

It is such a good thing I know better then drinking from there. Since we aren't taking our trip after all to Texas, I guess I will do that now. thanks for all the info you have on here. A wealth of stuff.

hankaye · 06-13-2012, 10:39 AM

Howdy All;

Something is bothering me about this Thread...

Tanks hold a certian amount when full.
Unless one has drianed the lines and Hot Water
heater, when full it will have the stated amount,
not more nor less.

Should the tank NOT fill to capacity then you may have
a kinked vent line from the tank to the atmosphere.
Easy way to see if the vent is obstructed, When you fill
it the tank will pressurize. If you find you have to hold the
fill hose 'firmly' to fill the tank, then, when you remove the hose
from the filler, you will get a rush of water from the filler...
Checked it out myself ...

Now for the pump cavating (getting air in the system), the point
that the pump inlet line is attached to your tank may be higher than
usual... or the sensor may be lower than usual. Those are my thoughts ...
Your's may vary.

hankaye

geo · 06-13-2012, 01:59 PM

Hankaye -

You are correct, tanks do hold a specific amount usually stamped or cast in the plastic for the record. However, quite a few folks, i used to be one, will read the specs and think "that's how large my fresh water tank is". Not so. Keystone adds the hot water tank, plumbing, and pressure tank to the total. After all, they ARE part of the water carrying capacity. And as i discovered during my tank heater installation, there's an "unusable portion" of the tank "at the bottom". Just think people should be aware, especially when boondocking.

Ron

f6bits · 06-13-2012, 02:06 PM

In my case, this is a good thing. All my tanks are 30 gallons, so I know I won’t be able to fill up my grey tank unless I refill my fresh water tank.

f6bits · 06-14-2012, 09:27 AM

In spite of geo trying to ruin my week, I enjoyed pulling the lid off the fresh water tank box and got a look at it. It’s 24.5 gallons, so that would put me close to 30 gallons with my water heater tank.

I’m also happy to say that my fresh water tank is a very nicely shaped rectangular prism with the output and drain tubes as close to the bottom as possible. Oddly enough, my sensors aren’t one above the other. They alternate between ends of the tank.

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