Tank monitor anomaly

[wave man]

Need to know if this is supposed to be this way...

My fresh tank was at about 44% and I was hooked back to city water and the pump was on. After a shower and related chores I discovered the fresh tank was now full at 100%.

I did not misread the beginning level nor the after, is this supposed to happen?

I haven’t read about this anywhere in a lot of reading... it’s great if it is intended but I know there’s all kind of backflow thingies and stuff in the plumbing to control direction and so on...

Enlighten me please, I’m getting paranoid that it’s something undesired...!
[emoji45]

Wave Man

[rmkrum]

No, you are not being paranoid. The water system IS out to get you..

There is a backflow check valve that is part of the water pump that is supposed to prevent city water from flowing backwards through the pump an filling the fresh water tank.

Two things here--the water pump, in spite of what people claim WILL NOT boost city water pressure. It only draws water from the fresh tank, so if you have low outside water pressure, just fill the tank, and run on the pump, without bothering to connect to city water.

It is sometimes possible to fix this 'stuck pump check valve' by disconnecting city water, turning the pump on, and running water down a sink briefly, on and off a couple times, making the pump cycle on and off. That will make the pump come on, surges of water flow through the check valve, and maybe get the problematical bit of debris out of the pump check valve.

The way to tell you succeeded, is to then shut the faucet and leave the pump on. If the pump then stops (like it should) and stays off for at least 15-20 minutes or more, you can figure your system is a) holding water pressure, and b) the check valve has re-seated itself. If the pump comes on briefly every few minutes, you have a leak somewhere, possibly at the check valve, or something else is leaking. Then the diagnostic fun commences...

A good practice, by the way, is to ALWAYS fill your fresh tank or connect to city water using an in-line filter on the potable water hose (the one designed for drinking water). That tends to keep particles OUT of your fresh tank and plumbing. I also use a quality adjustable water pressure regulator at the hose connection to reduce water pressure in the hose and AS plumbing to a reasonable level. The inlet fitting has a plastic pressure regulator and yet another check valve that does not always survive really high city water pressure, and the hose will balloon up and burst all over you if there is too much pressure on it as well. Not a good thing... I set mine to about 40 pounds on the gauge.

[OTRA15]

Originally Posted by rmkrum

. . .
. . . the water pump, in spite of what people claim WILL NOT boost city water pressure.
. . .

Beg to differ . . .

If you are connected to [low pressure] city water, and the water tank has sufficient water in it, turning on the pump WILL increase the pressure of the water being supplied to the various faucets, shower heads, and so forth inside the trailer.

This higher-pressure water should not back-flow into the city water supply, if the pressure regulator at the hose connection is working right. Most AS owner's manuals mention this "camping trick" IMO. Of course, if the water tank is empty, the pressure boost will not occur.

Low pressure city water is generally not a problem, except perhaps for taking a shower.

Cheers,

Peter


PS -- Ditto to your well-said comments on getting the pump's back-flow check valve to clear, so that the city water does not fill the water tank.

[wave man]

Swell. Just Swell.

So. What are the undesired consequences possible here? What do I have to worry about if my troubled Airstream has yet another defect...?

sigh....
Wave Man.

[OTRA15]

Relax

The pump check valve getting stuck open happens all the time, often because of a small piece of grit from unfiltered water put in the tank, or some plastic shard left in the tank during assembly.

rmkrum's advice is good.

Originally Posted by rmkrum

. . .

It is sometimes possible to fix this 'stuck pump check valve' by disconnecting city water, turning the pump on, and running water down a sink briefly, on and off a couple times, making the pump cycle on and off. That will make the pump come on, surges of water flow through the check valve, and maybe get the problematical bit of debris out of the pump check valve.
. . .

Using the new search function above with the blue bordered-box, "pump check valve" yields:

https://www.google.com/search?q=pump...=airforums.com

Generally a simple fix, with the worst being getting a new pump.

Happy Trails!

Peter

[TG Twinkie]

Leave the pump OFF when on city water. If the pump is running and you have greater pressure from city water it will flow back thru the pump. Since the pump opens the check valves when running.
My guess is the check valve is opening and closing rapidly in this case.

[wave man]

Appreciate the insights folks, thank ye

[Bobbo]

Originally Posted by TG Twinkie

Leave the pump OFF when on city water. If the pump is running and you have greater pressure from city water it will flow back thru the pump. Since the pump opens the check valves when running.
My guess is the check valve is opening and closing rapidly in this case.

This is not true. If the pump is ON and the city water pressure is higher than the pump's cut-off pressure, the pump just won't cut on. If the city water pressure is lower than the pump's cut-off pressure, the pump will cut on and add pressure to the water lines. The back-flow valve won't let the water flow backward unless there is a problem with it like debris stuck in it holding it open or it is defective.

[troubadour1]

Just to make this debate worse I think it could be a problem with the sensor. Those things give bad reads all the time.

[OTRA15]

Which "sensor" troubadour1?

Ditto to Bobbo. Well said.

Amazing how many misconceptions are floating around out there . . .

[troubadour1]

The one that tell you the % of tank. Mine has been very spotty.

[wave man]

Hmm, ok. I'll go off city water for a couple days when I get back and see if the sensor reflects typical rates of usage and capacity drop in the fresh water tank...

If the water is flowing into the fresh tank from city water what is wrong with that? Why is that bad?

"If the pump comes on briefly every few minutes, you have a leak somewhere, possibly at the check valve, or something else is leaking."
...it has done this since day one but I didn't know enough to recognize it as a sign of a problem. Nice...

Wave Man

[kendrick.l.j]

Hi Waveman, what you are experiencing seems to happen with all the models. The check valve will stick from time to time on my Classic. I now make a habit of checking the monitors a couple of time a day just to be safe. The above suggestion work very well and so far no damage. Not a big issue, at least not to me.
I’ve only been doing this RV lifestyle for just over a year and I have already learned to never assume things will work the way they are supposed to every day. I’m getting used to it. As long as it’s not major, I’m ok. I just add it to my list of things to fix when I take it up to JC once a year unless I can fix it myself.

[Bobbo]

Originally Posted by wave man

If the water is flowing into the fresh tank from city water what is wrong with that? Why is that bad?

The fresh water tank is not designed to be pressurized. If water is flowing backward through the pump's backcheck valve, when the tank gets full, it pressurizes to the pressure of the shore water system. That can do damage.

[OTRA15]

Ditto to Bobbo, and well said. In theory the city water running unchecked into the water tank would find its way out the fill spout or its vent tube, but those are small-volume paths, so yes pressure would build up in the tank.

There would also be lots of water leaking onto the ground, especially if you left the city water supply turned on while the trailer was unattended, or during the night while you are sleeping.

It is advisable to turn off the city water hose bib in those situations, even if it means the pump has to kick on when you flush the toilet during the night IMO.

With our old 25' back in the 90's we had a frost-damage hidden leak under the bed, which we only discovered in the middle of the night, because the carpet was soaking wet during a trip to the toilet. City water was on all night, so we had to take the bed apart the next day, fix the leak, and dry everything out. Fortunately we were in southern California, and the weather was dry and hot.



Lesson learned -- the hard way!

Good luck,

Peter

[wave man]

Appreciate the feedback folks!

[accordionman]

A few months ago we had hooked up at a park and just did everything normal until the next morning. I got up and found that I had a small pond outside the AS and that the fresh water tank was overflowing, which I thought was interesting given that it was not being filled ( at least I thought ). It was the check valve on the water pump allowing water to migrate into the fresh water tank. The fix for that trip was simply to fill and use the fresh water tank and not use the city water inlet. When I got home, we checked but the bypass valve was toast so we replaced the pump. Problem was solved.

One of the many adventures we experienced in our first yr of Airstreaming.

[OTRA15]

The search results linked in Post #5 suggest that this is a fairly common problem IMO.

[wave man]

Those of us who are not mechanically handy, new to the world of Airstreams(and all RVs), and search impaired value your tip offs OTRA15 , thank you.