Tempramental Water Pump

[Taidy]

Good morning all.

I have a 2012 Swift Charisma fitted with a FloJet water pump, Model R3426-500, rated at 25 PSI. Sometimes it works fine. Sometimes it takes ages to start up, almost to the point where the water stops flowing before it kicks in. Sometimes it doesn't kick in at all and I have to swear, switch the power off and come back later. Is this likely to be a faulty pump, pressure switch or wiring? Does anyone else have the same issues?

Thanks in advance

MJ

 

[ProfJohnL]

The pump should respond to the drop in pressure when a cold tap is opened, it may take longer when a hot tap is opened because as the cold water has been heated it will have expanded and increased the pressure in the hot pipework above the pumps threshold pressure. Only when the pressure in the hot system has reduced and the cold also begins to flow will the pump cut in.

There could be a number of causes for the symptoms you describe, and it will be difficult to resolve it conclusively through the forum.

My gut feeling is you may have a faulty Non Return Valve in the cold water feed to the water heater. This woul normally block any increased pressure in the hot system from preventing the pump starting the cold flow.

But it could also be a faulty pressure switch on the pump, or even a mixer tap being left open typically in the shower, where it allows mixing of hot and cold in the pipework even though the shower head is turned off.

You might benefit from having a surge damper on the cold water pipework.

 

[audiorob]

Might be worth starting with the pressure switch, either inline or on the back of the inlet - can sometimes need a fair bit of adjustment and also sensitive to the voltage, so for example may need to be adjusted between off grid and on EHU.
Worth downloading

https://www.whalepumps.com/rv/siteFiles/resources/docs/resource-library/WhaleAdjustingyourpressureswitchb.pdf

having not needed to touch mine for many trips it needed adjusting on our latest outing and i was pleased to have a laminated copy in my caravan file to help me out!
Don't want to underestimate your knowledge but have you had the ends of the spouts off and cleaned the filters? I leave mine hand tight and don't know here all the gunge comes from when I regularly rinse and blow them clean!

 

[Jcloughie]

Might be worth starting with the pressure switch, either inline or on the back of the inlet - can sometimes need a fair bit of adjustment and also sensitive to the voltage, so for example may need to be adjusted between off grid and on EHU.
Worth downloading

https://www.whalepumps.com/rv/siteFiles/resources/docs/resource-library/WhaleAdjustingyourpressureswitchb.pdf

having not needed to touch mine for many trips it needed adjusting on our latest outing and i was pleased to have a laminated copy in my caravan file to help me out!
Don't want to underestimate your knowledge but have you had the ends of the spouts off and cleaned the filters? I leave mine hand tight and don't know here all the gunge comes from when I regularly rinse and blow them clean!

The OP has an internal pump which tend to control their own pressure. So don't have the need for the adjustable Whale effort. I have never understood why external pumps need an adjustable pressure switch to cope with voltage variations. But internal pumps manage without.

John

 

[ProfJohnL]

The OP has an internal pump which tend to control their own pressure. So don't have the need for the adjustable Whale effort. I have never understood why external pumps need an adjustable pressure switch to cope with voltage variations. But internal pumps manage without.

John

Most inboard pumps utilise positive displacement. The pumps are capable of producing a rapid series very high output pressures pulses but the volume of water is relatively small, it's the volume of the pipework and it's natural elasticity which smoothes out the flow. If used without a pressure switch against stalled flow they are capable of hitting far greater pressure than the 1.5 to 2Bar a caravan system would be able to withstand. If the voltage varies as long as the motor rotates it will produce the pressure. The pressure switch is essential to prevent the pump from damaging caravan pipework and fittings.

In practice the effect of voltage change on a diaphragm pump will directly and proportionately affect flow rate, and it will take longer to reach the pressure switches threshold.

By comparison submersible pumps flow rate is not directly proportional to supply voltage, and becasue the impeller is not a close fit to the chambres out let port it can't build up pressure as well as a diaphragm pump.