Domestic water pump issue?

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Domestic water pump issue?

August 03, 2012, 06:47:19 pm

I just recently purchased a 1991 U300 and I'm now enjoying life as a full timer. I noticed that the domestic water pump runs for a split second, then shuts off for a minute or so, then runs another split second, then shuts off for a minute or so, and so on. The thing drives me crazy until I shut the pump off. There are no leaks anywhere that I can find and I'm not connected to the city water system. I realize the ice machine uses some water once in a while, but this is different. The gray water and black water tank levels don't seem to be going up and the domestic water level doesn't seem to be going down... Is there an air cushion in a bladder that needs to be adjusted or something?

Scott

Re: Domestic water pump issue?

Reply #1 – August 03, 2012, 07:11:57 pm

I had an issue with my water pump running a bit too often when I first got my Foretravel.

Though I changed out the water pump, the issue persisted. It turned out that the water valve under the bath sink was defective and was not closing all the way which was keeping the water lines from holding at the proper pressure.

I troubleshot it by going to the water manifold and turning everything off and waiting to see if the water pump would come on. Once I found that the pump itself wasn't the problem, I turned the valves on one every few minutes or however often your pump is turning on. Everything held except the shower/ city water valve and the valve under the sink needed to be replaced. Once fixed, the pump never comes on unless I am using water.

Re: Domestic water pump issue?

Reply #2 – August 03, 2012, 07:37:18 pm

Scott,

You might have a air bladder tank in the system, designed to avoid the pump running. Here is a link to one, . As I recall they should be pressured up to about 25# on the air bladder side of the system.

Re: Domestic water pump issue?

Reply #3 – August 03, 2012, 08:40:40 pm

One possibility is that the check valve within the pump is leaking slightly letting some water back into the fresh water tank. This could be checked by turning everything off at the manifold as suggested above. If the cycling continues the problem is between the pump input and the manifold.

Re: Domestic water pump issue?

Reply #4 – August 03, 2012, 10:15:56 pm

Scott your 1990 won't have the water manifold so you won't be able to test that way. I'd check the fresh water fill valve under the sink. (If that's where it is!) If that's not it it's probably the check valve in the pump. Hopefully someone here will let you know how to check that since I don't know.

Welcome to the Foretravel world!

see ya
ken

Re: Domestic water pump issue?

Reply #5 – August 03, 2012, 10:30:43 pm

Indeed, start by checking if you have an accumulator.

If so, verify that it is OK:

It will have a valve similar to a tire air valve. Use a screwdriver or similar to push in the center pin. If water comes out, replace the accumulator.

If air comes out, that means the bladder is OK. Use your tire gauge/air chuck to set it to 23 PSI, pressure water OFF, no shore water, pressure bled off by opening a faucet.

Brett

Re: Domestic water pump issue?

Reply #6 – August 07, 2012, 12:39:00 pm

I think the bladder is blown because when I pressed on the Schrader valve water spewed out under pressure. It's possible that it's just condensation, but the water isn't cold in this weather so I doubt it. I did notice a large release of air in the water system a while ago but never gave it a thought that the bladder might have blown. On larger tanks in well houses the bladders are replaceable, but I doubt this little one is. I guess it won't hurt anything if I leave it alone for now and fix it later when I have an opportunity... Hey, at least it's not a leak! Thanks for your help my friends.

... I'm driving to Maine next week by the way if any members are up there?

Re: Domestic water pump issue?

Reply #7 – August 07, 2012, 12:54:34 pm

Yes, the accumulator is shot. Replace it, as it is not serviceable.

This is very likely the accumulator you need (did not price shop, just googled it): Jabsco Accumulator Tank

Brett

Re: Domestic water pump issue?

Reply #8 – August 07, 2012, 01:51:20 pm

It is a Jabsco, but it's probably a 1 gallon tank instead of that 2 gallon tank because it's only about 7-1/2" x 10". I presume a lot of RVs don't have accumulators at all, so maybe I'll remove the tank if it really costs $400 to replace it? I can shut off the pump when it drives me crazy.

Re: Domestic water pump issue?

Reply #9 – August 07, 2012, 02:07:23 pm

RRadio,
Got our last accumulator tank at the big blue home improvement store for less that $100. We have seen them at the orange home improvement store also just look around in the home well section.

Pamela & Mike

Re: Domestic water pump issue?

Reply #10 – August 07, 2012, 03:37:54 pm

Quote from: RRadio – August 07, 2012, 01:51:20 pm

I presume a lot of RVs don't have accumulators at all, so maybe I'll remove the tank if it really costs $400 to replace it?

Wow, who wanted $400 for it. The quick search (above) I did came up with $169. Suspect a more thorough search might find one even cheaper.

And, I would not be without an accumulator. The pulsing without one or the thought of switching to the much less reliable variable output pumps doesn't appeal to me.

Brett

Re: Domestic water pump issue?

Reply #11 – August 07, 2012, 04:15:44 pm

The accumulator tank may also provide some "soft head room" for expansion of the contents of the plumbing system. Without a bit of cushion, changes in volume caused by temperature variations may cause leaks such as a "weeping" pressure relief valve on the hot water heater, or leaks in other places. The air cushion in the accumulator provides a pocket of compressible air to mitigate sudden, and possibly annoying, changes in water pressure.

We have a variable speed water pump, and I am pleased to leave a functional accumulator tank in the system. Experience and preferences of other folk are likely to be different.

Re: Domestic water pump issue?

Reply #12 – August 07, 2012, 06:06:41 pm

These expansion or accumulator tanks also have a small amount of " draw down " capacity that keeps your pump from short cycling. Something to keep in mind, make sure the tank you purchase is for domestic water use. If not your water system ends up tasting like an old tire inter tube.

Thanks, Mitch

Re: Domestic water pump issue?

Reply #13 – August 07, 2012, 07:03:02 pm

Tomorrow I'm relocating from Poole Knobs COE campground near Nashville to Cages Bend COE campground also near Nashville... and all the COE campgrounds near Nashville are beautiful by the way... I'll stop at the big blue and / or big orange home improvement store on my way tomorrow and see if I can find a reasonably priced expansion tank. It looks like it'll be an easy job to replace it... I'll let you know if I find one.

Re: Domestic water pump issue?

Reply #14 – August 07, 2012, 09:06:55 pm

Water pump accumulator is not needed with variable flow water pumps, like many of us are using. We no longer have accumulators. Accumulators can be problematic due to captive water that does not change, promoting germ growth.

Re: Domestic water pump issue?

Reply #15 – August 07, 2012, 09:27:37 pm

I use a 2 gal expansion tank I got new with shipping for $35.00 on ebay. They are made to be used on home hot water tanks.It works as it should with no leakage from the safety valve and the water in the tank is pushed out when ever I take the psi off the system. Gam

Re: Domestic water pump issue?

Reply #16 – August 07, 2012, 10:22:34 pm

As the water system Draws down between pump cycles the accumulator or expansions tank expels the water back in to the system, you will start bacteria growth in your half full domestic water tank vented to atmosphere long before you would an expansion tank.

Respectfully, Mitch Sayer

Re: Domestic water pump issue?

Reply #17 – August 07, 2012, 11:40:55 pm

RRadio,
I have the same year/model of coach. I recommend using an accumulator tank. I removed mine, had problems with the water heater relief valve seeping, and then reinstalled one that I picked up from a home improvement store (less than $40). No more relief valve problems. I installed mine under the kitchen sink with a length of flexible hose. The OEM location above the water pump is just too tight. You can install it anywhere in the cold water circuit and it will do it's job. Also, our systems are so small that all you need is the smallest version available.
I used SharkBite fittings to TEE into the existing water lines under the sink and a flexible hose to connect the tank so I could place the tank in a far corner and be able to pull it out to access the connections and the schrader valve. When I winterize my coach so I also place the tank with the fitting down so water will drain out. The hose is "reinforced clear" so I can see how much water is left in the line.
Good Luck.

Re: Domestic water pump issue?

Reply #18 – August 09, 2012, 11:59:17 am

It turns out my tank was a 2 gallon model. I went to the big blue home improvement store yesterday and found they had two different models in stock, a $40 with a one year warranty and a $50 with a five year warranty, so I went with the better one for ten dollars more. I installed it in the parking lot and immediately noticed a huge difference in the water pump's behavior. I presume the old tank had been malfunctioning for some time even before the bladder blew out because the new tank seems to have a much larger cushion / capacity than the old tank did even before it blew out. The new tank had 30psi on the bladder according to my gauge, so I left it that way. The new tank doesn't fit the straps quite as well, so I was only able to get one of the two straps around it, but it'll probably hold it up okay. Two gallons of water in the tank will weigh less than 20 pounds total. I'm driving to Maine next week and that'll be a good test to see if it holds up. If not I'll reengineer something if needed... Thanks for your help my friends!

Re: Domestic water pump issue?

Reply #19 – March 10, 2014, 05:18:54 pm

Quote from: kenhat – August 03, 2012, 10:15:56 pm

Scott your 1990 won't have the water manifold so you won't be able to test that way. I'd check the fresh water fill valve under the sink. (If that's where it is!) If that's not it it's probably the check valve in the pump. Hopefully someone here will let you know how to check that since I don't know.

Welcome to the Foretravel world!

see ya
ken

Ken...

I have the valve under the bathroom cabinet (1995 U300) but I see no way of servicing the unit without cutting the bottom of the cabinet floor!!

Any ideas..??

Thanks

Hans

Re: Domestic water pump issue?

Reply #20 – March 10, 2014, 06:28:19 pm

Quote from: sfbmw – March 10, 2014, 05:18:54 pm

Ken...

I have the valve under the bathroom cabinet (1995 U300) but I see no way of servicing the unit without cutting the bottom of the cabinet floor!!

Any ideas..??

Thanks

Hans

Hans,
In both my kitchen and bathroom cabinets there is a false plywood floor that is held down with square drive screws that are visible after the carpet is lifted. The false floor is about 4" above the main coach floor. I've recently had to replace the stem packing on the valve - it would leak a little when I open the valve (and tightening the stem nut didn't work). The main shutoff seal was good.
Good luck.

Re: Domestic water pump issue?

Reply #21 – March 10, 2014, 08:17:11 pm

Thanks John, your past advise about the heater issue was "right on"

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