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Author Topic: Filling fresh water tank  (Read 869 times)

2explorers

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Filling fresh water tank
« on: July 05, 2017, 09:56:25 PM »
Will be filling my freshwater tank on my new (to me) 5th wheel for the 1st time in a few days. How do I know when it's full? There's no indication that I can see that it's full. I don't want to overfill the tank and create any issues. It's a Carriage Domani I'm working with. Also, should I leave a little empty head space in the tank for towing purposes, or just fill it up all the way?
2008 Carriage Domani 31ft 5th Wheel
2011 F250 Diesel

Gary RV_Wizard

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Re: Filling fresh water tank
« Reply #1 on: July 06, 2017, 08:34:10 AM »
There will be a fresh water tank gauge inside somewhere, and some rigs have another in the outside bay as well.

The tank is vented and has an overflow, so no harm should come from overfilling unless there is a design flaw of some kind. Still, something to avoid when possible.

In some rigs the tank overflow line has been known to create a siphon action after an overflow that continues to pull water from the tank until it is near dry. If that turns out to be the case, leaving the tank not-quite-full avoids that problem.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

JoelP

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Re: Filling fresh water tank
« Reply #2 on: July 06, 2017, 08:45:02 AM »
I have been in the practice of only putting on half a tank of fresh water if I know that I am heading for another RV park where I will have a hookup to reduce the weight I carry and potentially make an improvement in mileage, but I am beginning to think it has little if any impact on mileage. Perhaps one of the more experienced people on the forum have already figured this out and will reply.
Joel from San Jose

2010 Itasca Suncruiser 37F
8.1L Chevy Workhorse with Banks PowerPack
2016 CMax Energi Hybrid dinghy

blw2

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Re: Filling fresh water tank
« Reply #3 on: July 06, 2017, 09:01:37 AM »
mine is a gravity fill tank
I generally just stick the hose in and let it fill till it overflows

I try to not fully open the hose bib so it doesn't fill too fast and "over pressure" the tank too much

when it's full the water overflows out the fill opening as well as the vent
But you can hear it getting full and could stop when it's close.....if you are patient enough to stand there the whole time its filling.

Now, I have read that some folks have had problems doing this, bursting the overflow, the tank, or some other fittings.  I generally have this in the back of my mind every time and worry about it.
but
I have inspected the vent hose and clamps, ensured everything is open and tight, so I feel kindof ok about doing it.  Still worry though in the back of my mind though.

Oh, and I did find when I first bought my MH, that the vent hose was too long and installed with a kink, I addressed that early on.

and then if your tank is set-up like Gary described so that a full vent tube will syphon the tank dry, I recon you could open the tank drain and drain a bit out just to brake the syphon.
Brad (DW + 3 kids)
13 Thor Chateau 31L Class C on Ford E-450
'06 Silverado
'05 Rockwood Freedom 1910 (5-1/2 years)
former tent campers

Stephen S.

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Re: Filling fresh water tank
« Reply #4 on: July 06, 2017, 11:48:18 AM »
If I'm filling it all the way up for boondocking, I just fill till it overflows. Going to a campsite with water, I just have enough for short stops on the road. The amount of water would do less to the MPG than driving speed. Wind resistance does more to hold the RV back than weight.
Stephen S.
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'99 Winnebago Chalet
2002 VW Beetle
2007 Yamaha TW200
Home town: Mableton, GA

Kevin Means

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Re: Filling fresh water tank
« Reply #5 on: July 06, 2017, 12:29:21 PM »
The mileage impact of a full vs. partially full tank will be imperceptible, but there may be a weight issue, depending on how a partular RV is loaded, and its weight limitations.

Our first Class A had a typical water tank setup - a vented tank with an overfllow. The overfllow, however, couldn't keep up with the water hose (gravity fill) and I almost blew my water tank up one day when I was filling it. Ever since then, I visually watched the water tank when I was filling it. (It was under the bed)

In all three of our Class As, when the tank level indicators were indicating full, the tanks weren't full. I could get several more gallons in them. That's no big deal if we were going to be hooked up to water somewhere, but we mostly boondock, and water is a valuable comodity when boondocking. Some RV's water tanks do siphon while driving if they've been topped off, so you'll need to determine if yours does that or not.

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
RVI Brake 2, Minder TM-66 TPMS, 970 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California

2explorers

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Re: Filling fresh water tank
« Reply #6 on: July 06, 2017, 02:32:20 PM »
Ok guys, thanks. Seems pretty straight forward. One other thing - after filling the tank and turning on my water pump, will my pump stay on until the hot water heater is full? I'd hate to turn on the water heater when it's not full and burn out the heating rod.
2008 Carriage Domani 31ft 5th Wheel
2011 F250 Diesel

Lou Schneider

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Re: Filling fresh water tank
« Reply #7 on: July 06, 2017, 03:01:21 PM »
You have to let the air out of the hot water tank.  Turn on the pump, then open a hot water faucet. When you get a steady stream of water the tank is full.

Triple Slide Jayco

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Re: Filling fresh water tank
« Reply #8 on: July 06, 2017, 07:11:01 PM »
There will be a fresh water tank gauge inside somewhere, and some rigs have another in the outside bay as well.

The tank is vented and has an overflow, so no harm should come from overfilling unless there is a design flaw of some kind. Still, something to avoid when possible.

In some rigs the tank overflow line has been known to create a siphon action after an overflow that continues to pull water from the tank until it is near dry. If that turns out to be the case, leaving the tank not-quite-full avoids that problem.

Ahhh. this is what must be happening to mine.! I was going to start a new post asking why my overflow (underneath) steadily streams water when my tank is full. It must be creating a siphon effect until I turn on the pump and it kind of slows it down to a slow stop. I got it now. THX
2016 Jayco TT Triple slide 33RBTS
2016 Chevy Tahoe

2kGeorgieBoy

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Re: Filling fresh water tank
« Reply #9 on: July 13, 2017, 12:02:04 AM »
You need to make sure your hot water tank fills while you are filling your fresh water tank. Otherwise, you will pump 6 gallons of water from your fresh to the heater, leaving you short 6 gallons. Opening the safety valve on the tank will allow it to vent and when water flows from it, shut it off. The tank is now full.
2000 Georgie Boy Maverick
31' E450 V10  No slides
our toys:
'08 Polaris Touring LE ATV (mine)
'12 Polaris 550 XP ATV (wife's)
1968 AH Sprite (original owners, not on road at this time)
Gary, Jena, and Presley (our awesome yellow Lab).
Westcliffe, CO.

Rene T

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Re: Filling fresh water tank
« Reply #10 on: July 13, 2017, 05:22:28 AM »
You have to let the air out of the hot water tank.  Turn on the pump, then open a hot water faucet. When you get a steady stream of water the tank is full.

I agree, but only if the bypass valves are positioned correctly. The only way to verify that is by filling the system including the tank, then go outside and open the pressure relief valve at the top. If you get soaked, the tank is full.
Rene & Lucille & co-pilot Buddy
AKA  Pep N Mem
2011 Chevy Duramax 2500 HD 4X4
2011 Montana High Country 343RL
From the Granite State of NH
& Florida Snowbird in Lakeland FL

decaturbob

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Re: Filling fresh water tank
« Reply #11 on: July 13, 2017, 12:28:23 PM »
Will be filling my freshwater tank on my new (to me) 5th wheel for the 1st time in a few days. How do I know when it's full? There's no indication that I can see that it's full. I don't want to overfill the tank and create any issues. It's a Carriage Domani I'm working with. Also, should I leave a little empty head space in the tank for towing purposes, or just fill it up all the way?


are you planning on sanitizing the system?
proud to have a 2008 Tioga 31M MH

Old Blevins

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Re: Filling fresh water tank
« Reply #12 on: July 13, 2017, 01:19:10 PM »
When I fill up with water and need to fill the hot water tank, I usually hook up to the city water connection first and use its pressure for that chore.  I just like to save my water pump all that work since I have a handy alternative.  After I've done that, then I fill the fresh water tank (till it overflows - but I haven't had a siphon problem) and then run the water pump for both hot and cold to make sure everything is working right.  In the grand scheme of things, this probably doesn't save the pump that much work, but most uses are not as sustained as filling the HWT and I'm a little.... compulsive.
Jim
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2006 Silverado SRW 1-Ton 4WD Diesel
2006 Arctic Fox 29V
1985 Brawley 2-Horse Straight-Load Trailer

allenb12

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Re: Filling fresh water tank
« Reply #13 on: July 13, 2017, 03:40:44 PM »
The first day we first took delivery of a 2013 Forest River Sierra.  I filled the water tank and went inside. Heard creaking and popping then a big bang.  The water tank was on the ground.  The dealership sent a person out the next morning.  He discovered that the overflow had been plugged at the factory.  The tank just expanded and broke the supports.  I purchased a little in line flow meter that I now use and know exactly haw many gallows have been put into the tank.

Triple Slide Jayco

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Re: Filling fresh water tank
« Reply #14 on: July 13, 2017, 04:53:07 PM »
The first day we first took delivery of a 2013 Forest River Sierra.  I filled the water tank and went inside. Heard creaking and popping then a big bang.  The water tank was on the ground.  The dealership sent a person out the next morning.  He discovered that the overflow had been plugged at the factory.  The tank just expanded and broke the supports. I purchased a little in line flow meter that I now use and know exactly haw many gallows have been put into the tank.

Great idea, here is one from Ebay.

http://www.ebay.com/itm/New-Orbit-Hose-End-Water-Usage-Flow-Meter-Measure-Tool-for-Outdoor-Yard-Garden-/222427201155?epid=608160612&hash=item33c9b1be83:g:AAMAAOSwSlBYuFVz

 Since all the tank fill levels are unrealistic on the control panel inside the campers, this is a great idea.
2016 Jayco TT Triple slide 33RBTS
2016 Chevy Tahoe

Old Blevins

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Re: Filling fresh water tank
« Reply #15 on: July 13, 2017, 07:28:28 PM »
Since all the tank fill levels are unrealistic on the control panel inside the campers, this is a great idea.
You know, that's a very good point.  If "they" made a flow meter you could connect in line with your water pump, and it had a remote display so you could see how much water you had used, it would allow you to manage your consumption a little better when you're boondocking.  There's an RV gadget I'd like to have.  You could easily calibrate it to your RV by filling the tank full, then running the water pump until it started sucking air.
Jim
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2006 Silverado SRW 1-Ton 4WD Diesel
2006 Arctic Fox 29V
1985 Brawley 2-Horse Straight-Load Trailer

 

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