Water Pressure Problem

[jviss]

Summary: Jabsco 36800 pump won't always shut off.

O.K., guy and gals, put on your thinking caps! (I love this online diagnosing stuff, except when it's my stuff that needs diagnosing!)

I have a freshwater system that includes a Jabsco 36800-1000 water pump, feeding a 2 gallon expansion tank, and then off to a tee which feeds a 10 gallon water heater and the cold distribution.

Everything seems to work O.K., and there don't seem to be any leaks, except that on occasion, and lately more often than previously, once a tap is opened and enough water runs to trigger the pump, the pump runs continuously, as if it can't build up pressure. I don't (yet) have a pressure gauge in the system, but it seems there's enough pressure.

Usually, since I got the boat last year, as the pump approaches shut off the sounds changes and then there's a choppy, or stuttering that gradually decreases in frequency 'til the pump shuts off. Like "bop, bop, bop, bop, ....bop...bop.....bop.......bop." The analog Ammeter needle bounces in time with these 'bops.' Also, the cold water hand pump in the galley would dribble while the pump runs. Now, when it fails to shut off, I get neither the 'bops' nor the dribble.

I suspected the pressure switch, but without the dribbles I'm not so sure.

Taking a pic for this post I noticed a label that reads:

WATER PUMP SWITCH
TURN SWITCH OFF AND OPEN
FAUCET TO RELIEVE PRES-
SURE WHEN UNATTENDED.​

I don't do this when I leave the boat. This weekend is the worst experience with these pump symptoms, and the system had been left for one month.

When it does this, when it won't shut off, I have "fixed" it at times by:

• running some water in the sink, then shutting the tap, and it then goes into its shut-off machinations - but not always;
• shutting off the pump breaker and waiting a while.

None of these "foxes" is reliable or repeatable, that I can tell. It seems to work when it wants to.

Does anyone have experience with this pump, or this kind of system, and have any ideas as to what the might be the issue?

Thanks very much,

jv

p.s. I would just swap out the pump but the best price I've seen is $445. Yikes!
p.p.s. also soliciting input on that belt; it rides halfway up the pulleys like that, and stays there, except once it did come off.

Sagittarius Potable Water Pump

• jviss
• Sep 30, 2018

 

[dlochner]

Inside the pressure tank there is a rubber bladder, on one side is water, on the other air with a schraeder valve (bicycle inner tube valve). When the pump pressure rises the tank the air is compressed, when the tap is opened the air pressure then pushes the water out. First check the valve to see if it is leaking. Pressurize the tank and put a drop of spit on the valve. If it is leaking, the spit will bubble out. Tight the valve stem or replace it if it leaking.

The next culprit is the pump. The diaphragm may have a small leak between the supply tank and the pressure side. So long as there is room in the pressure tank the water pumps, but when that tank reaches pressure the hole or tear in the diaphragm allows water to back flow in to the supply tank. Since the pressure never builds up enough to trigger the pressure switch, it just keeps running.

I had a similar set up with a Jabsco pump and tank. Both are now sitting in my basement. I replaced it with a Shurflo Aqua King. No problems sense, easier winterization, and fewer connections.

 

[Ken Cross]

It sounds to me like you aren't getting enough pressure to shut the pump off. A pressure gage will tell you what you have.
I based this on you saying the manual pump no longer drips. The pressure switch has a certain hysteresis. It turns on at one pressure and off at a higher pressure. The idea behind this is to keep it from frequent cycles. If the pressure switch is failed it may be or may not be at both high and low levels, but it could be the switch, but that would then be a case of too high a pressure before it turns off. Even a temporary pressure gage connected to a faucet would give the answers you need. The problem for me is knowing what pressures should be.

Ken

 

[jviss]

Thanks Dave and Ken. I think I may have multiple problems. Since posting this I've fallen deep into the internet, and found some information on this pump.

Here's the troubleshooting guide:

Screenshot 2018-09-30 10.40.55

• jviss
• Sep 30, 2018

from:
http://www.xylemflowcontrol.com/files/43000-0102.pdf

(I posted the guide as an image because the text cut and paste formatting was ugly.)

• Pump operates roughly and has excessive noise and vibration. YES.
  • Intake line is restricted, kink in suction hose or fittings too small. MAYBE. I'm using 1/2" OD, 3/8" ID tubing for all potable water.
  • Pump mounted on flimsy board. NO.
  • Deformed or ruptured pulsation dampener in pump. MAYBE, no way to tell now.
  • Loosened screws at pulleys and connecting rod. MAYBE, will check.
  • Worn connecting rod bearing. MAYBE, but I doubt it, as the boat has low hours. Not sure how to check.
• Pump fails to stop when faucets are closed. YES.
  • Empty water tank. NO.
  • Insufficient voltage to pump motor. MAYBE, will check.
  • Defective pressure switch. MAYBE. Planning on installing a pressure gauge.

I found a service kit for $100, P/N 30122-000; can't find a list of kit contents, though, but looks like a bunch of rubber parts. Found a pressure switch for $25, P/N 37121-0010.

 

[jviss]

I replaced it with a Shurflo Aqua King.

Dave, what GPM pump did you get? They are available in 2, 3, 4, and 5 GPM, from $120 to $310.

(My Jabsco is rated 3.3GPM.)

Thanks,

jv

 

[dlochner]

I think I used a the 3gpm pump. I can't see the label to see the model number. The ratings will tell you how many faucets that it will support. That is a meaningless metric. The only time we have more than one faucet running for more than a few seconds is in the fall when draining the tanks or in spring after shocking the water tanks.

A slightly lower flow rate will also help preserve water. An issue if access to fresh water is limited or expensive.

Check Defender, the pump is under $100.

 

[jviss]

I think I used a the 3gpm pump. I can't see the label to see the model number. The ratings will tell you how many faucets that it will support. That is a meaningless metric. The only time we have more than one faucet running for more than a few seconds is in the fall when draining the tanks or in spring after shocking the water tanks.

A slightly lower flow rate will also help preserve water. An issue if access to fresh water is limited or expensive.

Check Defender, the pump is under $100.

Thanks! I imagine a 3GPM pump would be fine. I was thinking that if I keep the accumulator it will only affect how quickly if can bring that up to pressure.

Did you dispense with the accumulator?

 

[jssailem]

Did you dispense with the accumulator?

I use a shurflow 3 gal/Min Mfg# 4138-111-E65 pump which I bought to replace the old pump when it failed. Have an old accumulator. I have discovered it is improperly oriented (does not work correctly, positioned on it's side air valve horizontal). When using hot water, the pump takes some time to turn on using the pressure in the HW tank to mitigate the need to turn on. I suspect there may be a bit of air in the HW tank (working like an accumulator). When I turn on the cold water tap, the pump starts almost immediately. Nice flow pressure. Then shuts down (no accumulator function). Depending on the type of use you put the pump through (long hot showers) I suspect a functioning accumulator would be a welcome addition to your system. I'd keep it. I am replacing my old accumulator this fall. I will position it to the proper orientation, air valve on the top ("vertical").

 

[jviss]

I will position it to the proper orientation, air valve on the top ("vertical").

Yes! I think they work well either air valve up or down. Mine was down when I go the boat. This makes it nearly impossible to drain when winterizing. I turned it to valve up, and put in a ball valve so once drained, I can isolate it so I don't have to fill it with antifreeze in the winter (another 2 gallons!).

 

[JamesG161]

Have an old accumulator. I have discovered it is improperly oriented (does not work correctly, positioned on it's side air valve horizontal). When using hot water, the pump takes some time to turn on using the pressure in the HW tank to mitigate the need to turn on. I suspect there may be a bit of air in the HW tank (working like an accumulator).

I did an Accumulator Analysis for Fresh water systems.
Read it at your own risk!
https://forums.sailboatowners.com/i...ter-accumulator-analysis.180421/#post-1311270
Jim...

 

[LeslieTroyer]

Older accumulators don’t have bladders and can become waterlogged. If the don’t have an air valve on top you need to drain completely, the air trapped inside becomes your buffer.

 

[capta]

These pumps have two valves inside as well as a diaphragm. A single hair can make either valve leak and not allow the pump to come up to pressure. Usually, if the diaphragm is bad there is water around the pump. Lastly, it could also be the switch. It only requires removing the 4 bolts on the top of the pump housing to get into it and check the valves. As these bolts screw into plastic, when closing the pump, they must be tight but do not strip out the plastic threads.
I love these pumps and consider them reliable if you understand how they work. 90% of the time when they fail it's because one of the valves has a bit of something in it, though sometimes when used as a bilge pump the valves can corrode and need replacement. Any marine parts dealer should have the valves in stock.

 

[jviss]

Thanks Jim, I just read it. I can't say I agree with all of it, but I appreciate your view. FWIW, I have a 2 gallon potable water expansion tank as an accumulator. My pump switch set points are 20 and 40 psi. One of the great benefits of an accumulator is no pump noise when rinsing hands late at night! It also saves wear and tear on the pump, especially diaphragm pumps.

(A friend has a very expensive boat (Morris) with a variable speed pump with no accumulator. Hates it. Wishes he had an accumulator and a regular pump.)

I think I'm going to go ahead and rebuild my pump and replace the pressure switch, and investigate the diameter of the line from the tank manifold to the pump; I think it should be larger than the 3/8" ID line I have.

 

[JamesG161]

It also saves wear and tear on the pump, especially diaphragm pumps.

I think I did say that and included less vibrations for future line leaks.
Check out the SBO posters who agreed with my analysis.
Just remarking for a friend...
Jim...

PS: I tell the Admiral to open the faucet for full, not pump start/stop type dribble operation.

 

[capta]

Thanks Jim, I just read it. I can't say I agree with all of it, but I appreciate your view. FWIW, I have a 2 gallon potable water expansion tank as an accumulator. My pump switch set points are 20 and 40 psi. One of the great benefits of an accumulator is no pump noise when rinsing hands late at night! It also saves wear and tear on the pump, especially diaphragm pumps.
(A friend has a very expensive boat (Morris) with a variable speed pump with no accumulator. Hates it. Wishes he had an accumulator and a regular pump.)

I think I'm going to go ahead and rebuild my pump and replace the pressure switch, and investigate the diameter of the line from the tank manifold to the pump; I think it should be larger than the 3/8" ID line I have.

You can pick up a Square D pressure switch at any hardware store and adapt it to fit your system (I usually T it into the line after the pump). They are much cheaper, more reliable and you can set whatever pressure you want your system to run at, with one of them.
You can either leave the old one in place or put a pipe plug into the hole in the pump.

 

[jviss]

You can pick up a Square D pressure switch at any hardware store and adapt it to fit your system (I usually T it into the line after the pump). They are much cheaper, more reliable and you can set whatever pressure you want your system to run at, with one of them.
You can either leave the old one in place or put a pipe plug into the hole in the pump.

That's a great idea. Which switch are you thinking of? The only ones I've seen online aren't adjustable, and cost at or more than the Jabsco switch.

 

[capta]

That's a great idea. Which switch are you thinking of? The only ones I've seen online aren't adjustable, and cost at or more than the Jabsco switch.

Just a quick search came up w/a huge variety, like this one @$19.00, a great deal cheaper than any "yacht" pressure switch on the market. Some are adjustable, some not. You just tighten or loosen a nut.
https://www.ebay.com/p/Square-D-FSG...-Switch-30-50-PSI/2254930677?iid=400656784823
or:
https://www.ebay.com/p/Square-D-9013FYG2J21-Pressure-Switch-Pumptrol/1307660787?iid=302810002458

 

[jviss]

Thanks.

 

[dlochner]

Did you dispense with the accumulator?

Yes, no accumulator. It may still be in my basement taking up space.

 

[Ron20324]

After speed-reading the replies, I don't think anyone mentioned a clogged filter on the pump input. It sounds like the pump is starved for water, be it an empty tank or blockage of the line. Maybe even a kink in the line or something squeezing it? When I empty my water tank, I get those very conditions. FWIW, the last thing I do when locking the boat up is turn off the water pump breaker and openeing the faucet to relieve pressure on the hoses. Cheap insurance.