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Topic: Water pressure tank fil anomoly (Read 652 times) previous topic - next topic

Water pressure tank fil anomoly

Twice now, when I have failed to use a pressure regulator because I thought the pressure was low enough, something strange has happened to make me want to understand exactly how my water system works.  The U320s are very different with their valving than the U270s, as everything is manual for me.

The normal scenario:
I hook up the city water hose, turn the Audit on to see the water level, then I go into my bathroom and turn a ball valve so that the tank fills rather than the city water pressurizng the system.  No electrics at all.  Simple, like older RVs.

BUT.  When the city water pressure becomes excessive, however, what has happened both times is that the tank has started to fill.  The bathroom ball valve has not been opened, or forced open, by the pressure, but something certainly has opened.  I caught this one before the tank completely filled, and stuck the regulator back in the line where it belonged, and everything is normal.

Does someone know the plumbing of this?  While I appreciate that it must be some sort of safety release, I would like to know where it is and possibly I would choose to direct the water out and onto the ground, rather than fill or overfill my fresh water tank.

The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)

Re: Water pressure tank fil anomoly

Reply #1 –
(Just guessing here) Don't most RV water pumps incorporate a back flow check valve?  Perhaps it is malfunctioning or being overpowered?
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Water pressure tank fil anomoly

Reply #2 –
Quote from: cajk –
(Just guessing here) Don't most RV water pumps incorporate a back flow check valve?  Perhaps it is malfunctioning or being overpowered?

Really good guess.

I know that if I open the fill valve to fill the tank, the drop in pressure in the coach will turn on the water pump.  So we are careful to switch off the 12 volt pump now when we fill the tank.
Dave Cobb
Buckhorn Lake Resort The Club, #6202, Kerrville TX
check the map.  I do rent it out when I am traveling!
2001, U320, 36' #5887, in Kerrville, FT Club #17006, (7/23 to present)
2024 Jeep Grand Cherokee L, Summit, white
EX: 98 U295, 36' #5219, (mid door), (4/13-10/23)
EX: 93 U225, 36' (4/11 to 4/13)

Re: Water pressure tank fil anomoly

Reply #3 –
brad
I had a similar problem. when hooked up to city water, my tank would slowly
fill. the water was going backwards through the water pump. I replaced the
water pump, and carry the old one for a spare.

Re: Water pressure tank fil anomoly

Reply #4 –
Quote from: Wayne Macauley –
brad
I had a similar problem. when hooked up to city water, my tank would slowly
fill. the water was going backwards through the water pump. I replaced the
water pump, and carry the old one for a spare.
The first time this happened (there was a problem in the RV park) was 2008...and I am still using the same Aquajet Variable.  It does seem to be sounding a little more "rumbly" as it works after this second incident...  Sounds like I better get a spare.
The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)

Re: Water pressure tank fil anomoly

Reply #5 –
Quote from: Brad & Christine Slaughter –
.......................Twice now, when I have failed to use a pressure regulator because I thought the pressure was low enough, something strange has happened to make me want to understand exactly how my water system works.  The U320s are very different with their valving than the U270s, as everything is manual for me...............................
Brad,
 It may be perfectly normal for your pump.  Many of us have the SHURflo 4048 RV ByPass pump.
Ignoring shore water influences for the moment, the 4048 pump operates normally up to about 30 psi, where a spring loaded bypass valve opens, allowing flow back from the output side to the input side, providing smooth, steady flow with virtually no cycling, all the way down to a trickle. As a faucet is opened back up, the pressure will drop, the bypass will close and full flow is again obtained. This allows good flow, even with today's restrictive showers and pullout sprayer faucets.

In a U270, when you open the fill valve under the bathroom sink, you are lining the shore water up to the pump outlet.  Thus, if shore water pressure is greater than 30 psig, say 32 psig, you will have a 2 psig driving head pressure that will slowly fill your fresh water tank through your 4048's bypass valve.  The higher the shore water pressure is, the faster your tank will fill.
It's much safer to keep shore water isolated and your fresh water tank in motion. 

When the fresh water tank level becomes low, turn off your pump, then open the shore water fill valve only to fill you fresh water tank, close the fill valve, turn your pump back on and let the 4048 supply a consistent, reliable water pressure  Always turn off the pump power switch whenever you leave the coach unattended.  That keeps the fresh water tank in-motion, fresh/healthy and isolates you from shore water pressure excursions which you will otherwise never be able to accurately protect against.
Neal
 
The selected media item is not currently available.
Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten

Re: Water pressure tank fil anomoly

Reply #6 –
I had this happen at a campground in New Mexico on the drive home from picking up my coach in California.  The water seepage into the fresh water tank overflowed all night, much to my surprise in the morning.  I apologized to the campground owners and got out of there quick. 

The ball valve under the sink wasn't making a tight seal and replacing it fixed the problem. 
Robert
Build # 5304
1998 34' U270 Cummins 6CTA8.3

Re: Water pressure tank fil anomoly

Reply #7 –
I'm gonna have to take the pump and check it out.  I have the ARV55 pump, having replaced the problem pump that came with the coach.  But I think you have all pointed me to what must have been a backflow through the pump. 

Neal, I normally use city water when hooked up, but am constantly also using the pump to add pressure when taking showers.  Thus the fresh water tank stays, as you say, "in motion" all the time.  I never leave the pump switch on when out of the coach.  When I added the other 2 switches to control the pump, I seriously considered adding another (with light) at the front exit.  I may yet.  I think this 7 year old pump, with the 2 year warranty, is due for a replacement.  It has served me well.
The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)

Re: Water pressure tank fil anomoly

Reply #8 –
Quote from: Brad & Christine Slaughter –

Neal, I normally use city water when hooked up, but am constantly also using the pump to add pressure when taking showers. 

I think that I have read that when we install the pressure reducer on the campground hose connection we are really reducing the flow as much as the pressure.  So then we get worst shower head pressure than we like from our pumps.  Remember reading to get an actual pressure control and then you get flow you might like.  Their was a huge difference in the cost of the two different items.

After seeing a Youtube video of a 5th wheel that was total loss due to a toilet valve failure that flooded the trailer, I never leave the park hose on, and we turn off the pump when leaving the coach.
Dave Cobb
Buckhorn Lake Resort The Club, #6202, Kerrville TX
check the map.  I do rent it out when I am traveling!
2001, U320, 36' #5887, in Kerrville, FT Club #17006, (7/23 to present)
2024 Jeep Grand Cherokee L, Summit, white
EX: 98 U295, 36' #5219, (mid door), (4/13-10/23)
EX: 93 U225, 36' (4/11 to 4/13)

Re: Water pressure tank fil anomoly

Reply #9 –
Quote from: Dave and Dolly Cobb –


After seeing a Youtube video of a 5th wheel that was total loss due to a toilet valve failure that flooded the trailer, I never leave the park hose on, and we turn off the pump when leaving the coach.
The only time a water hose is hooked up to our coach is when I am filling the fresh water tank. We always use the internal water system and never, except when we forget ??? , leave the coach with the water pump turned on.

Roland
1993 U280 4341
2010 Jeep Liberty
The Pied Pipers

Re: Water pressure tank fil anomoly

Reply #10 –
Fortunately, I have a Marshall Brass RV pressure regulator that I bought 30 years ago, when they were not too restrictive to flow. If I needed a new one today, I would buy an adjustable model made for residential use.

I try to turn off the water pump switch when leaving, but cannot say I never leave it on.

I do leave the park water on unless I plan to be away for a while. I know this is a risk, but a small one.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer