Fresh water problem, air in the lines ?????

[polarlyse]

I'm having a problem with my fresh water system. Specifically irregular flow probably from air in the system. This is our first outing with a trailer that is new to us. It's an '85 Excella. Before leaving home I put some water into the tank. 15 gal. so I would have some water on the road. Prior to leaving while hooked up to the house water flow seemed normal. On the road using the pump however it is irregular and spurting from the faucets ( hot & cold). The pump comes on and will run for a long time before shutting off. The water heater seems to be working OK.

Prior to first connection, while still at home, I found the inlet and outlet lines at the pump disconnected for winterization. I connected them and while hooked to the hose the system seemed fine. Now, from the tank it's not working very smoothly. Today I was looking at the system and I find the inlet line from the tank appears dry. No water in the inlet line filter either. But at the faucets I get water spurting out. I'm running low on water in the tank so will have to add more to continue this troubleshooting session. At this point I'm baffeled. It may simply be low level enough to suck air in and I'll clear that up when I add water. But I can't figure out why the pump suction line is dry and still provinding water to the sink ??????

So, Airstream land, anyone out there have more experience with these trailer plumbing issues than me, I hope you have a simple fix that will clear this up. I read about by-pass valves at the water heater tank and have not yet found them either.

Thanks in advance for any help you may be able to provide. You guys are great, keep it up.

Thanks,
Roger in NJ

[TBRich]

Let us know if this is fixed when you add water to your fresh water tank. It sounds like the pump is trying to pump but not bringing water into the system from the tank....either because the water level is too low or the pump itself is allowing air into the system rather than bringing in water. As to getting spurts of water through the faucets, perhaps there is enough water in the lines from when you were connnected to city water to get some water out at the faucets in spurts of water and air... It definitely sounds like you have air in the lines.

[Mexray]

1. sounds like the water level in the tank is so low, that the pump is sucking air...

2. with adequate water in the tank, and continued air in the lines, I would re-check those hose connections you mentioned on both sides of the pump...could be sucking air on the inlet to the pump...or you could have a crack in the pump housing, or a failed gasket in the pump that's sucking in air - caused by freezing with a bit of water left in the pump during winter??

3. I had this problem and traced it to a cracked plastic elbow down at the tank - the pump inlet hose was attached to this elbow, and the crack wasn't big enough to drip water by itself, but would suck air into the hose when the pump ran...this elbow was a thin-wall plastic 'cheapo' part, and I couldn't believe AS would use such an item! I replaced the elbow with some improved piping and it should last till the cows come home...

[polarlyse]

Well, back to the water problems today. I filled the fresh water tank so should end the issue of possible low water. Still got a lot of air in the tank. Found the filter on the suction line to be sucking air. If I held the bowl in my hand and pressed it began to suck "some" water and showed some improvement. Removed the filter housing and put in a temporary fitting to eliminate the filter. Some improvement but not the cure. I disconnected the suction fitting at the pump and found it dry. Held my finger over the inlet and find very little suction, almost none in fact. My conclusion at this point is that the pump is not pulling enough suction to draw enough water into the system. So I think I'll look and see if there is a repair kit for the pump and try that.

Back to it
Roger

[polarlyse]

OK, finally I think I'm on the right track. I read further in the "FORUM" and someone had mentioned about priming the pump. Now, why didn't I think of that one. Anyhow, I did it and things are working so much better. Not perfect yet, but satisfactory. It began to suck water from the tank and flow reasonable well. I tried to tighten down the bowl on the filter and put that back in also. The filter is still sucking air. If I press on the bowl with my hands I can hear the pitch of the pump change and it begins to pull water at a much greater rate so I'm sure the filter is the culprit. I will work on a replacement.
As it stands now things are OK to use and if I can get the new filter I think all will be up to standard.

Thanks to all on the forums, all you gotta do is look around here and all we need to know is either on the forum or in the head of a member.

Thanks again all,
Roger

[Mexray]

I believe that once you get the input piping and filter fixed without any leaks, the pump should self-prime without any difficulty...

If the pump is still sucking air, then it's probably the rubber element inside the pump...don't which type you've got, but they do eventually wear out or tear, causing you're problem...

It's hard to find rebuild kits for older pumps...which was the case for ours. I replaced the entire unit with one of the newer variable-flow type pumps, and it works great! I got mine from West Marine...

[dlb435]

You're sucking air. There is a leak in the vacuum side of the pump circuit. One of the most common spots is the filter housing (it may have an o-ring that can dry out). It could also be any of the lines or fittings from the tank to the pump. The pumps are positive displacement type and generaly don't need to be primed. I had the same problem, took 10 minutes to fix.

[polarlyse]

Well dlb you are right on the money. Exactly right. The other day while scratching my head I had the filter housing in my hand. With the pump running I squeezed the clear plastic bowl and the pump pitch changed and water began to flow as it should. Anyhow, I got a new filter and changed the suction lines from semi rigid reinforced plastic with barb fittings to a flexible but more rigid tubing with pressure fittings. Took all of less than 10 min and done. Water flows as expected without air in the lines.

Thank you for all your input and advice.
I'm visiting in Kansas now and next week will be off to St. Louis, Mo on the way home.

Thanks again all,
Roger