Variable Speed Freshwater Pump...Suggestions?

[Frank60]

I know this is an old thread, but it fits my question. I'm looking at the Johnson WPS 5 pump. My current pump is Flojet 4.5gpm, 30 psi (2.1 bar). The Johnson is 5 gpm and 50 psi (3.5 bar). Is it fair to assume that any yacht plumbing should be designed to handle 50 psi? Any possible issues? My boat is all Pex plumbing with press-on fittings. A bit worried about my old water heater.

[silverp40]

PEX plumbing usually handles at least 60 psi, ,usually more for municipal pressure.

[TrentePieds]

PEX is designed for shoreside applications, and the unions and other fittings designed for it will hold far more than 50PSI. The mandated pressure relief valve that is fitted between municipal/city water supply and the domestic plumbing is usually calibrated for 80PSI.

You may very well have shoreside "shark bite" fittings on your PEX. They, too, will hold well over 50PSI, indeed well over 80PSI.

But how do you know that it really IS PEX you have?

TrentePieds

[rslifkin]

Much of the original plumbing on my boat is grey plastic pipe from the 80s with metal fittings on it. Original water system ran at 40 psi, I'm currently running it at 60 psi with no issues. I'd be surprised if there's many fresh water systems out there on boats that won't handle 50 psi.

[Coltrek]

Originally Posted by Frank60

I know this is an old thread, but it fits my question. I'm looking at the Johnson WPS 5 pump. My current pump is Flojet 4.5gpm, 30 psi (2.1 bar). The Johnson is 5 gpm and 50 psi (3.5 bar). Is it fair to assume that any yacht plumbing should be designed to handle 50 psi? Any possible issues? My boat is all Pex plumbing with press-on fittings. A bit worried about my old water heater.

I am sure it will handle it. I have that pump, and even tho I have been hard on it, (ran maybe a 2 - 3 days dry), it still works famously, altho after that dry run it is a little noisier, but never blown any leaks in a 20 year old boat.

[Frank60]

Originally Posted by TrentePieds

But how do you know that it really IS PEX you have?

TrentePieds

It looks like PEX. 15mm Red and blue plastic pipe with push/fit connectors. What else could it be?

[GordMay]

PEX Tubing has hydrostatic pressure ratings of to 80 ➛ 160 psi, depending upon temperature.
200°F at 80 psi, 180°F at 100 psi, & 74°F at 160 psi
➥ https://www.pexuniverse.com/pex-tubing-technical-specs