Water Keeps Running with No Supply (Stupid Question)

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

Lonestar Guy

Well-known member
Joined
Jun 13, 2018
Posts
70
Location
Texas
OK, my stupid question for the... until my next one. Prepping trailer for upcoming trip. Have been working on shower faucet, so had water hooked up and subsequently tested all faucets in the rig. Days later, disconnected the water (which had been OFF at the source for a couple days) and moved trailer to my driveway. The aux pump is NOT turned ON, but when I turned on any of the faucets, water at first flowed like the supply line was hooked up! It continues to flow, slowing down, but I'm surprised at how much water keeps coming out with no pressure to drive it. It's still more than a trickle. Mind you, I haven't let it run and run until it stops because I don't want more water in the grey tank. I just don't recall it ever taking this long to relieve the pressure built up in the lines. It's probably been 1/2 gallon all together(?)... hard to tell. I can't make any other assumption other than this is 'normal' and I've never done this right after disconnecting the water... or just bad memory? :confused:
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
74,628
Location
At our Silver Springs FL home
A half gallon does seem like a lot to drain off residual pressure. Does your RV have an accumulator in the water system? That stores some pressure. The water heater might do that too, if there is a check valve at its inlet and it was turned on for awhile
 

Lonestar Guy

Well-known member
Joined
Jun 13, 2018
Posts
70
Location
Texas
A half gallon does seem like a lot to drain off residual pressure. Does your RV have an accumulator in the water system? That stores some pressure. The water heater might do that too, if there is a check valve at its inlet and it was turned on for awhile
Hmm... not sure. I will check. I'm only turning on the cold water side, for the most part. I don't doubt there's water in the hot water tank, but it seems it would still require pressure to flow from there.
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
74,628
Location
At our Silver Springs FL home
Hot water does require pressure to flow, but heating the water build some. Not a lot, but some. And its possible for it to backfeed pressure to the cold line. An accumulator is a more likely bet, though.
 

Kirk

Well-known member
Joined
Oct 30, 2005
Posts
979
Location
Full-time , Escapee
There are several different types and sizes of accumulators. Most are pretty small and contain a quart or so of water but there are also a few that are much larger.
41P7jBkjJcL._AC_SR320,320_.jpg
61c21B4rDHL._AC_SS450_.jpg
 

Lonestar Guy

Well-known member
Joined
Jun 13, 2018
Posts
70
Location
Texas
Hot water does require pressure to flow, but heating the water build some. Not a lot, but some. And its possible for it to backfeed pressure to the cold line. An accumulator is a more likely bet, though.
Thanks Gary. Just to fill in the blank, I never had the hot water heater turned on. At any rate, I just let it run a bit more from both hot and cold sides and it finally stopped. I have not had the time to determine if there is an accumulator nor understand why a trailer like mine would have one. We'll see.
 

Lou Schneider

Site Team
Joined
Mar 14, 2005
Posts
11,167
Unlike a house water heater, an RV water heater is designed to operate with an air pocket at the top of the tank to allow the water space to expand into when it's heated. The water doesn't have to be hot to compress the air in this pocket, and normally there's a one way valve to prevent pressurized water in the tank from backflowing into the cold water lines. If your one way valve is missing or defective it can cause the water in the tank to backfeed into the cold water lines and provide a bit of flow.
 

NY_Dutch

Well-known member
Joined
Nov 22, 2010
Posts
6,966
Location
Where our wheels take us!
Thanks Gary. Just to fill in the blank, I never had the hot water heater turned on. At any rate, I just let it run a bit more from both hot and cold sides and it finally stopped. I have not had the time to determine if there is an accumulator nor understand why a trailer like mine would have one. We'll see.
An accumulator allows water to be drawn with fewer pump starts and stops for less wear and tear. I installed a 2 gallon accumulator in our motorhome that lets us flush the toilet several times before the pump kicks in during the night.
 

Lonestar Guy

Well-known member
Joined
Jun 13, 2018
Posts
70
Location
Texas
Unlike a house water heater, an RV water heater is designed to operate with an air pocket at the top of the tank to allow the water space to expand into when it's heated. The water doesn't have to be hot to compress the air in this pocket, and normally there's a one way valve to prevent pressurized water in the tank from backflowing into the cold water lines. If your one way valve is missing or defective it can cause the water in the tank to backfeed into the cold water lines and provide a bit of flow.
OK, thanks. Will keep that in mind.
 

Lonestar Guy

Well-known member
Joined
Jun 13, 2018
Posts
70
Location
Texas
Since you are located in the D/FW area, we may not be that far apart as I am based in Mesquite. I'd be happy to assist if i can.
Thanks, Kirk... sorry, just getting back to the site as I had to post another issue. I'm not sure what the deal was with this. We took our trip and there were no issues. I'll just have to keep an eye on it and maybe test it again soon.
 

Aaron5er

Active member
Joined
Sep 10, 2021
Posts
41
Location
NE Georgia
I'm curious about that much water flow without the pump on also.
I don't have an accumulator and only get a half cup of water when I forget to turn my pump on.
I'm following this one....
 
Top Bottom