odd problem with freshwater system

L

lime4x4

Member
Jul 24, 2007
341
Palmerton,Pa
Boat Info
1986 268 searay weekender
Engines
5.7 vortec alpha
Replaced all the freshwater hoses with pex tubing. When i turn on the cold water it always keeps spitting like there is air in the line. But yet i can run the hot water and it never spits out air. The hot water side is supplied by the cold water side so if it's air then the hot water side should be effected as well. The pump runs when pressure gets low then shuts off when pressure is restored
 
How long did you let the cold water run? Same thing happening at all faucets? Is your fresh water tank full?

It could be a loose fitting in the cold line. Did you use the push-connections? The tube actually goes in pretty far. Try re-seating all the connections.
 
I have a 30 gallon tank. I filled it twice now. It happens at both faucets. I used the pex tubing that gets crimped on. I've let the cold water run till the tank was almost empty and it's still doing it yet
 
Sounds like you are pulling air in at one of the fittings. Bad crimp maybe?
 
I rechecked the crimps and there all good. If i had a bad crimp it would also leak water. I kept the water system on for 2 straight days and the water level never went down in the tank. Plus there was no water at any of the crimps
 
Could it be the way your pump is delivering water pressure to the faucet? Perhaps the hot water tank is acting like an accumulator to where the problem doesn’t surface on the hot side. To test this prognosis: run multiple faucets, or both hot and cold side to see if the pump pressure won't deliver stable pressure.

Just my .02 ...
 
A bad crimp could suck air (like a venturi) if the leak were on the downstream side of the connection. But it would leak (water) when under pressure.

The pump doesn't cycle at all when all the faucets are closed?
 
pump doesn't cycle when faucets are closed. We had the boat out yesterday for 4 hours and the pump never ran once
 
The hot water tank has a check valve in it to prevent the hot water from being sucked back out of the tank and into the cold water lines.
Could your problem be the vent hose is plugged to the tank and that is why the cold water spits and not the hot water??? The hot water tank is an accumulator but the cold is straight pressure.


Ken
 
99.9% sure that you have a loose fitting between the tank and the pump. As advised, check all the fittings - the pump is sucking air!
Warren
 
It is definitely air leaking into the supply side. look for the following

fitting at tank damaged or not airtight
damaged tubing between tank and pump
leaking fitting at supply side of pump
pump plate loose or leaking
strainer fittings or strainer seal
and if you have a filter
filter fittings, filter seal, filter bleed valve
 
I filled mine yesterday and had the same problem .I put a new o ring on the fill cap and every thing was fine .I would inspect the inlet connections and oring first.
 
The odd thing would be that you don't have air on the hot side. The water water heater feeds cold water at the bottom and as it heats it becomes less dense and rises, then discharges hot water from the top. Air is less dense than water so after getting water out of the hot lines it should spit some air. However I do think that you are sucking air on the suction side. If you had a leak on the pressure side it would show up and out side the piping system ad water, not inside the piping system as air.
 
1956olds said:
I filled mine yesterday and had the same problem .I put a new o ring on the fill cap and every thing was fine .I would inspect the inlet connections and oring first.
Click to expand...


I just don't understand what the filler cap o-ring has to do with his problem. The suction line for the pump is below the water line down near the bottom of the tank. If it is sucking air, one would think that it would have to be at the pump (assuming that there is sufficient water in the tank & the suction tube in the tank is solid and does not have any holes in it).

~Ken
 
electricaldoctor said:
I just don't understand what the filler cap o-ring has to do with his problem. The suction line for the pump is below the water line down near the bottom of the tank. If it is sucking air, one would think that it would have to be at the pump (assuming that there is sufficient water in the tank & the suction tube in the tank is solid and does not have any holes in it).

~Ken
Click to expand...

I was wondering the same thing. In addition to the above, the vent line is always open to the atmosphere, so why would it matter if the cap didn't seal right? '56 - could you expand on this a little more?
 
Yeah you can leave the tank fill cap off and it won't matter.
 
I vote for sucking air on the supply side... Turn on the cold faucet and look at the clear screen filter you might see air bubbles there which will tell you if it's sucking in air from the supply side. If so check the fittings from the tank outlet to the pump.

If you don't see any air bubbles in the screen filter its either the pump itself or the housing around pump is sucking in air.... Since you don't see it in your hot water your leak is pretty small I would bet, so it may not be obvious to find..

Good luck!!!
 
Well, as stated above it's the classic symptom of sucking air somewhere before the pump- but that would not be isolated to the cold water side, it would have to be both hot and cold.

Very odd...let us know if you get it figured out. Inquiring minds want to know...
 
I tried it with the cap off and all i got was air bubbles in the water,the o ring was missing so i replaced it.drained the tank again with only a minute of bubbles then clear water.Filled and drained twice more same thing .Dont know why just the way it happened .mabey he has as mine a lot of pink stuff in his system too?
 
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