Air in lines!! Help

[screamineagle]

When Dry Camping after I fill the tanks, as the tanks get lower I start getting air in the lines. The lower the tanks get the worse it gets. I have a 43 foot 395M with 2 water tanks. I have replaced all the valves on the nautilus panel, The water pump, check valve on hot water heater, tightened up every fitting and clamp I can see. Here is the kicker when running the water there are no signs of leaking anyplace including the low spot in the coroplast, this I poked a very small hole it to see if water came out. The issue is driving me crazy and what I would really like to know is a good way to test the system. Should I pressurize the system with 40psi of air and see if I hear anything. I am running out of ideas. One thing for sure it is worse towards the front of the trailer meaning when I turn the faucets on. Right now the trailer is winterized so I will being working on it again soon. I am trying to avoid pulling the coroplast down from the bottom of the trailer if I can avoid it. [

[DougW9876]

Air in the water lines with the pump running is almost certainly coming from a leak on the inlet side of the pump. The clear plastic filter is a pretty common place for this to happen. It could also be any place along the water lines between the tank and the water pump, it sometimes takes a bit to find the culprit you just have to keep looking until you find it.

[screamineagle]

Definately not the pump or the bowl.

[FT4NOW]

Have you checked the check valve on the city water inlet? The white hose connection for city water fill has a built-in check valve.

[dryfly]

Air in the water lines with the pump running is almost certainly coming from a leak on the inlet side of the pump. The clear plastic filter is a pretty common place for this to happen. It could also be any place along the water lines between the tank and the water pump, it sometimes takes a bit to find the culprit you just have to keep looking until you find it.

I would agree. Since you have constant water pressure generated by the pump, any leak in the line would be pushing water out, and not letting air in.

[screamineagle]

Have you checked the check valve on the city water inlet? The white hose connection for city water fill has a built-in check valve.

Yes bought a plug and capped it off

[FT4NOW]

Yes bought a plug and capped it off

Does your air problem always occur at the same water level? Wonder if it could be the water pickup line was installed too high in the tank or there is a kinked line somewhere (one of the flexible ones, not PEX).

[Dutchman2]

When Dry Camping after I fill the tanks, as the tanks get lower I start getting air in the lines. The lower the tanks get the worse it gets. I have a 43 foot 395M with 2 water tanks. I have replaced all the valves on the nautilus panel, The water pump, check valve on hot water heater, tightened up every fitting and clamp I can see. Here is the kicker when running the water there are no signs of leaking anyplace including the low spot in the coroplast, this I poked a very small hole it to see if water came out. The issue is driving me crazy and what I would really like to know is a good way to test the system. Should I pressurize the system with 40psi of air and see if I hear anything. I am running out of ideas. One thing for sure it is worse towards the front of the trailer meaning when I turn the faucets on. Right now the trailer is winterized so I will being working on it again soon. I am trying to avoid pulling the coroplast down from the bottom of the trailer if I can avoid it. [

Has the system worked fine in the past?

If this is a new issue it seems you have covered the basics for the water pump/lines air cavitation points. The one thing that does come to mind is the potential for one of the cut out sections from doing the tank install at the factory fell into the tank and has migrates down to the suction pickup and partially blocks it off causing the pump to cavitate. Could also be a large piece of debris. If it was to cavitate again this coming season I would remove the water pump inlet line from the tank and using an air compressor back flow the line with air the clear any obstruction. Reconnect the line and test to see if this resolves the issue temporarily. It might help to isolate the issue.

Looking to other in the forum here for comment. Has there ever been a report of the vent line becoming kinked or plugged up? Just thinking this could create a negative pressure in the tank inducing the potential for the pump to cavitate from excessive negative pressure. It would be a stretch I now.

Dutchman2

[Riverbug]

I'd try air in the lines first to see if that helps you locate the leak/suction issue. I found a leak under the bathroom sink in our previous camper while winterizing. It was just a drip that I didn't notice until I hear air "squeaking" out of the faucet fitting. Because I set the compressor to 40-50psi I can close the faucets when moving from one to the next and that's when I found the leak. Now I use that as a routine check each time I winterize.

[screamineagle]

Just saw this, great Idea. The company that makes the nautilus panels sent me new valves to install also. Thanks. cover comes off it this weekend.