Losing water pressure when using fresh water pump

[Hawgman-THOR]

2017 Thor Windsport 34F. Just purchased it. Now chasing down gremlins

As the title says, when using the fresh water pump, after about 20 seconds the water pressure dwindles down to a trickle. Turn the water off, let the pump run until the system is pressurized, turn the water back on, and it is good for about another 20 seconds then loses pressure again. Also, there is a LOT of water line hammering noise in the walls. Not what I have heard from previous RVs that I have owned. It is LOUD.

Pulled the bed apart to access the pump. First thing I noticed was the inline filter was positioned sideways, and the screen was removed and laying in the compartment. Turn on the water and I could see an air bubble quickly forming in the inline filter. So I put the screen back in it and positioned it so the cup & screen were at the 6 o'clock position. Turned the water back on and same scenario. After 20 or so seconds, lose water pressure. But did not see air in the line with the filter positioned correctly.

Does not have a pressure issue when connected to fresh water. It is not hot water side or cold water side specific. And it does not matter which faucet is being used.

So, before I invest in a new water pump, looking for suggestions if there are any.

Thanks!

 

[16ACE27]

When you lose pressure, is the pump still running? If so, it may becoming air bound OR there is an obstacle in the FW tank blocking the outlet.

So, before going any further, verify:

The antifreeze suction line is capped off properly.
No suction isolation valves (FW outlet valve) are closed.

If all good, then connect an alternate FW supply to the antifreeze suction and see if you have the same issue.

 

[blw2]

I've noticed that in my rig it takes a long while for the air in the lines to the shower to clear. Until it does the water hammer and pipe slapping in the wall continues. The pipe slapping happens no matter which faucet is being used. It seems to be the shower that needs to run. I can take a full shower or three to clear.


Just thinkin' out loud here, but I'd try to make as sure as I can that the strainer is sealed and the air isn't getting pulled into the suction line. Then I'd give it some time using the water throughout the rig to see if the air will work its way out.

If it doesn't, I'd look for other suction side leaks.

 

[SGilbert]

Have you checked the pre filter just before the pump? Sounds like you have debris in it.

 

[Hawgman-THOR]

When you lose pressure, is the pump still running? If so, it may becoming air bound OR there is an obstacle in the FW tank blocking the outlet.

So, before going any further, verify:

The antifreeze suction line is capped off properly.
No suction isolation valves (FW outlet valve) are closed.

If all good, then connect an alternate FW supply to the antifreeze suction and see if you have the same issue.

Antifreeze line is capped off, FW outlet is closed. I will try an alternate water supply to the pump

I've noticed that in my rig it takes a long while for the air in the lines to the shower to clear. Until it does the water hammer and pipe slapping in the wall continues. The pipe slapping happens no matter which faucet is being used. It seems to be the shower that needs to run. I can take a full shower or three to clear.


Just thinkin' out loud here, but I'd try to make as sure as I can that the strainer is sealed and the air isn't getting pulled into the suction line. Then I'd give it some time using the water throughout the rig to see if the air will work its way out.

If it doesn't, I'd look for other suction side leaks.

We have taken six painfully annoying showers so far with the issue happening. Strainer is definitely sealed and o-ring lubed.

Have you checked the pre filter just before the pump? Sounds like you have debris in it.

As I mentioned, when I first checked it out the mesh filter screen was not even in it. I put it back in, and it is clean.

With the way that I found it, I am fairly certain that the previous owner had this issue with it and could not figure it out.

 

[Chateau_Nomad]

Sounds like a suction side air leak. If the pump runs, it's probably not the pump itself.

 

[blw2]

since the strainer was out of it....it wasn't there to protect the pump
safe bet that 99.9997% of all tanks have debris in them (that statistic is like most you'll find online...made-up)
and so odds are your tank has or at least had debris in it.
so maybe there's debris in the pump.

This doesn't address the idea that the previous owner couldn't figure it out, exactly
but it does address a potential result from running it without the strainer!

Otherwise, Suction side leaks can be a real bugger. Hard to find. I've got a little experience with it....I worked for about 5-6 years designing and servicing industrial chemical feed systems...basically pumping systems with a wide variety of different kinds of pumps pumping all sorts of liquids.

When I first bought my RV... brand new from a dealer.... it was sucking air in at the strainer. My strainer has a clear plastic screw on cap. Someone had overtightened it and there was a crack in the threads. Impossible to see. When the cap was off the crack closed up and disappeared. It could only be seen when the cap was tightened and then only once you knew it was there. I found it by seeing microbubbles forming under the transparent cap when the pump was running.
Fittings and valves can leak and it's nearly impossible to know.

 

[Hawgman-THOR]

Thanks everyone. I will definitely work on trying to identify a suction side leak to start.

 

[Chateau_Nomad]

Starting a new expression for a meme...

"I'm not an engineer... but I did sleep in my motorhome last night."

 

[dkoldman]

Just a thought... warning I have SOB, but can I play along :coolsmiley:

When I put my valve in Tank Fill position to fill it up, if I forget to put it back to Normal I will have what you have described with water sputtering out.

Also , can't you disconnect the output of the side and run to a bucket or something to verify the pump is working properly with steady stream?

Are you saying this happens with all faucets or just the shower?

 

[Hawgman-THOR]

Just a thought... warning I have SOB, but can I play along :coolsmiley:

When I put my valve in Tank Fill position to fill it up, if I forget to put it back to Normal I will have what you have described with water sputtering out.

Also , can't you disconnect the output of the side and run to a bucket or something to verify the pump is working properly with steady stream?

Are you saying this happens with all faucets or just the shower?

No fill/fresh valve. Fill is gravity feed on one side of the coach, fresh is a separate fitting on the other side of the coach.

Happens with all faucets, both temperature sides.

Yeah, checking the output would be (somewhat) simple enough.

 

[Hawgman-THOR]

Okay, finally had time to jerk around with this further.
The problem was not an air leak, it was not the pump, and it was not debris somewhere. It was a 90 degree piece in the ridiculous erector set configuration of a supply line that the factory used.

Tried the suggestion of an alternate water source in the winterize line. Had the same problem. Had a spare pump so swapped out the pump and the inline filter. Still same problem. I yanked out everything from the water tank to the inline filter, installed a new cut off valve and a new line. Voila!! Good constant water pressure.

So then I wanted to see if I could figure out where the issue was. Started by blowing air through the pipe. Was like blowing through a straw. Closed the shutoff valve and blew through the winterize port. Same thing. Used an air compressor to blow through it, still very little flow. Blew the opposite direction, same thing. So it has to be that 90 degree piece in there. Reason I sound so confident in it being that stupid 90 is because I have the same thing in my drain line and it took almost 4 hours to drain the tank before I started working on it.

 

[Hawgman-THOR]

This is what the factory setup looked like, and what the new setup looks like

 

[Hawgman-THOR]

While I was at it I located and isolated the pipe rattling noise. The output line was laying against the water tank and when the pump would pulse it would bounce off of the tank. I also did some insulation / isolation work around the pump before I put the bed back together. It is amazing how much quieter everything is now. And while I was feeling industrious I installed a Clean Camper Bidet on the toilet

 

[16ACE27]

Okay, finally had time to jerk around with this further.
The problem was not an air leak, it was not the pump, and it was not debris somewhere. It was a 90 degree piece in the ridiculous erector set configuration of a supply line that the factory used.

Tried the suggestion of an alternate water source in the winterize line. Had the same problem. Had a spare pump so swapped out the pump and the inline filter. Still same problem. I yanked out everything from the water tank to the inline filter, installed a new cut off valve and a new line. Voila!! Good constant water pressure.

So then I wanted to see if I could figure out where the issue was. Started by blowing air through the pipe. Was like blowing through a straw. Closed the shutoff valve and blew through the winterize port. Same thing. Used an air compressor to blow through it, still very little flow. Blew the opposite direction, same thing. So it has to be that 90 degree piece in there. Reason I sound so confident in it being that stupid 90 is because I have the same thing in my drain line and it took almost 4 hours to drain the tank before I started working on it.

So the plastic shavings from the tank got hung up in that corner adapter and blocked water flow from the tank. They never even made it to the suction strainer.

Good job hunting it down!

 

[ghnl]

Good job hunting it down!

Second that!

I suspect if you dissect the restrictive fittings you'll find it isn't the fitting themselves but the debris from installation they trapped.

 

[Hawgman-THOR]

So the plastic shavings from the tank got hung up in that corner adapter and blocked water flow from the tank. They never even made it to the suction strainer.

Good job hunting it down!

Thanks. What a pain in the ...

Second that!

I suspect if you dissect the restrictive fittings you'll find it isn't the fitting themselves but the debris from installation they trapped.

That was my initial thought too. But I think I should have been able to clear it when I hit it in both directions with 150 psi of air from my compressor. But it made no difference.