Fresh water puzzle

[Jamesorr]

After winterizing my 32 foot Nordic tug I started to flush the anti freeze out of the system. When I shut the boat down every thing worked. When I tried to flush the system I could not get my faucets to run without spurting a ton of air. I checked for leaks- none. I replaced my old shurflo flo pump (3.5 gpm) with a new shurflo flow aqua king II (4 gpm). Still sputtering. I thought my water filter housing may have a leak so I bought a new one and installed a fresh cartridge- still sputtering.
I bypassed the water filter and then everything flowed perfectly.
I cannot figure out why when I run the water through the filter system it sputters or just hisses air- when I bypass it I have no problems. I had the old water filter on for 5 years with no problems.

Any thoughts would be appreciated

Jim orr

 

[PM]

Just a thought..Did you bypass the water heater or is it filled with air? Release the air pressure which builds as it fills and the "spurts" should stop

pete

 

[STB]

It can take a while for the air in the system to work its way out. There is usually a pretty good volume of it and the pumps don't move it as efficiently as water. How long did you let it bleed? Are the water heater, expansion tank, and water filter canister full?

In some sense the surprising thing to me is that bypassing the water filter fixed it, not that there is sputtering as air is expelled during the initial return to service.

If there is air being expelled, but no water leak (not just no leak found), the problem is most likely either (a) a large volume of trapped air taking time to be fully expelled, e.g. water heater or expansion tank or hose volume or filter, etc; or (b) on the suction (input) side of the freshwater pump, where air can be sucked in without water coming out.

If there were a leak on the output (pressure) side of the pump, I'd expect water to come out somewhere -- although boats being boats, it might be hard to find. In many places, it could just be back-filled with water, without air coming in. But, in some cases, especially like a water heat or expansion tank, the air could just be trapped and only make its way out sporadically -- but there still should be a leak somewhere, where the water is coming out to make room for the air.

I guess what I am saying is this, in my thinking, either there is trapped air and you just need to bleed it more to get it out; or there is a leak on the input side of the water pump; or there is a leak in some vessel, like the heater, expansion tank, or filter, where air is getting trapped and only making its way out sporatically.

 

[Jamesorr]

I did not bypass water heater - just the filter. Did not take long to purge the water heater of air- maybe a minute or do and then it pumped water.
The new pump has a screen filter and the only thing I haven’t tried is removing the bowl and connecting the filter and see if that works. Otherwise I’m at a loss - almost like the filter system inhibits the water too much - even though it’s new and all fittings are tight

 

[STB]

James,

Where is the filter with respect to the pump? Is it on the suction side or the pressure side? In other words does it come "before" the pump or "after"?

Thanks!
-Greg

 

[Comodave]

Did you say that when you bypass the new filter the air bubbles go away and come back when you put the new filter in line? If so it may just be air trapped in the filter element. We have one in our RV and it takes forever to get all the air out when we replace the element.

 

[Jamesorr]

Thanks for all the feedback! Puzzle is solvef( after 3 days). The new pump comes with a strainer and that coupled with an existing water filter creates too much back pressure. I removed the strainer and reinstalled the water filter and she works beautifully. Apparently you can over filter the water !