Short cycling fresh water pump

[Graham_Wright]

After installation, the Jabsco 25 psi pump ran around every half hour.

Then it started pressure restoring around every two minutes. I could hear a water flow but there were no leaks anywhere in the system. There was apparently no leak-back through the Jabsco leaving only a Whale foot pump as the probable culprit and supported by using a listening sick around the system. )The Whale is connected in parallel with the Jabsco.)

Removing, dismantling and cleaning the Whale (not a quick or dry process!), improved the pressure restoration to hours.

Then it started short cycling again. Possible dirt in the new water tank?

Installing a pre-filter made no difference.

Removing the Whale again, it seemed one of the valves had curled back into its seat.

Anybody know if it is likely the rather delicate NR valves in the Whale cannot cope with the 25 p.s.i?

In an installation with only the foot pump, it would stall when the accumulator back pressure dictated it to. Connected as I have it may not be fair.

I will try contacting Whale but my experience of receiving help from manufacturers is not good. Fortunately, installing a separate NR valve in the Whale discharge hose would be straightforward.

 

[philip_stevens]

I had exactly the same problem with the Jabsco foot pump valves, and resorted to a Non-return valve in the output line of the foot pump.

Be aware that the NR valve is only 13/14mm wide, and will not fit into a push-fit fitting properly, and as in my case, it can get "blown" out. I had to fit a short length of copper pipe into the push-fit fitting, with a piece of braid hose jubilee clipped onto it, and the NR valve jubilee clipped into this. No problem with cycling pump since.

Make sure the accumulator has enough air in it. My one leaked through the plug at the top until I fitted a new washer.

 

[coopec]

Graham

We have a pressure pump hooked up to our solar HWS. For the first ten years after it was installed it gave no trouble but then it started to cycle even though there were no taps on (not even dripping). The plumber said the pump has an in-line "air cushion" (not his words) which , being air, can be compressed so that the pump will not recycle until it senses there is no pressure. Once a tap is turned on the pump will work and even after the tap has been turned off the pump will run for a short time until the air cushion is compressed. He said there is no such thing as a perfect seal and the air cushion has to be recharged over time. He took his bike pump on to the roof, hooked it up to the pressure pump and pumped it up (probably about 10 strokes). Now it is working perfectly.

If you haven't got an accumulator tank then maybe you need this sort of thing?

Whitworths Marine: Shurflo Accumulator Tank
https://www.whitworths.com.au/main_itemdetail.asp?cat=133&item...‎
When used in a water pressure system the Shuflo Accumulator tank smooths water faucet pules and eliminates pump cycling and "water hammer" giving smooth ...

https://www.google.com.au/#q=marine+pressure+pump+accumulator+tank

 

[Graham_Wright]

If you haven't got an accumulator tank then maybe you need this sort of thing?

Whitworths Marine: Shurflo Accumulator Tank
https://www.whitworths.com.au/main_itemdetail.asp?cat=133&item...‎
When used in a water pressure system the Shuflo Accumulator tank smooths water faucet pules and eliminates pump cycling and "water hammer" giving smooth ...

https://www.google.com.au/#q=marine+pressure+pump+accumulator+tank

I have an accumulator (in fact two - one for hot and one for cold but I've forgotten the logic!).

The fact that I can hear gurgles in the foot pump I'm sure is an indication of a leak back. I believe the NR valve will fix it.

(No reply from Whale yet).

 

[coopec]

Graham

You seem to be right on to it but I just did a google on recharging accumulator tanks in RV water systems and came up with

Testing

Precharge the accumulator tank with air using a standard Schrader air valve, the familiar type of valve used on bicycle and car tire tubes. Before using your new accumulator tank, check the pressure at the valve with a air pressure gauge. Most systems are set to around 20 lbs. per square inch (psi). Follow the manufacturer's suggestions, and pressurize the tank if necessary.
Turn on the water pump and check for leaks. Your water pump should run long enough to pressurize the system and fill the new tank, and then remain off as your accumulator tank fills the demand for water and keeps the system pressurized.

Read more: http://www.ehow.com/way_5984303_rv-pump-accumulator-tank-installation.html#ixzz2xXgSPRPa

 

[coopec]

Graham

What sort of HWS are you using?

If your water system is Jabsco based then you could be interested in this

4. Draining Facility
A drain cock or plug should be installed to permit the tank to be recharged with air. Install the drain plug at the low
est point in the system (after the pump). This will also allow the system to be drained down for winter lay-up.

I'm about to start on my yacht water system so all this is interesting to me.

http://www.marinemechanic.com/New-Folder2/accumulator.htm

 

[KellysEye]

>Then it started short cycling again.

Take the bottom of the pump off and the check the two diaphragms for a split.

 

[Graham_Wright]

>Then it started short cycling again.

Take the bottom of the pump off and the check the two diaphragms for a split.

I'm sure it is the foot pump; read #4.

 

[vyv_cox]

I assume you will go for a NRV with a ball or some sort of substantial flap? Ones I have bought at chandleries have only a bit of rubber as the flap and their life has been short. Plus in low pressure systems, which doesn't apply to you, the rubber curls and does not seal.

 

[Graham_Wright]

Plus in low pressure systems, which doesn't apply to you, the rubber curls and does not seal.

……which is what I think happened in the Whale.

 

[Graham_Wright]

The non return valve seems to have sorted it and Whale confirm their foot pump can't take back pressure.