Water System Upgrades


At the last RV rally we attended I noticed a wet spot on the ground under the utility compartment.  Further checking showed that the entire compartment floor was flooded.  As the fresh water tank, the water pump, all the various control valves for the water system, and the water heater are all in this compartment, the leak could be from almost anywhere.  Finally, using a flashlight and mirror, I found that the water heater was leaking, apparently from the tank itself, not just a fitting.  A new water heater was in my future!

After getting home, I removed the water heater and disassembled it to the point I could find a couple of pin holes where the tank had corroded through over it's 17 year life.  I ordered a new one from one of the few online sources where I could find the exact configuration I needed to replace my old one.  These heaters come in several variations.  First there are 6 and 10 gallon units.  Mine is a 10.  Then there are three configurations: propane only, propane and electric, and propane, electric, and heat exchanger.  The heat exchanger circulates engine coolant through a pipe welded to the tank and heats the water as you drive, so you have immediate hot water when you reach your destination.  Mine was the heat exchanger model.  $600 later it was on its way to me.

While I had the heater out, I had great access to the rest of the water distribution system.  I have never liked the way Foretravel (and most other motorhomes) handle the fresh water tank overflow.  They simply run a tube from the top of the tank out to under the coach somewhere.  This works great at preventing you from over filling the tank.  The excess runs out onto the ground without damaging anything in the rig.  The problem is when you are driving and turn away from the drain, the water presses against the side of  the tank and starts running out the overflow.  No matter how much water I start out with, I seldom reach my destination with over 90% of my tank capacity remaining.  The other problem with the Foretravel system is that the overflow drains out right over the rear bulkhead, which has a known problem with rust weakening the attaching screws and causing a failure.  That is not a good place to dump any water!

I have come up with what I consider to be a total solution to this problem.  If you attach the overflow hose on one side of the tank, then route it to the other side before exiting the compartment, water sloshing toward the drain has nowhere to go,  Water sloshing the other way cannot exit the tank to begin with.   I decided to implement this type of routing of the overflow hose while the water heater was out.

The other problem I noted was that the many ball valves in the system were beginning to fail.  The one on the water outlet from the tank shows rust stains and evidence of leakage, while one of the drain valves dripped slowly after I used it.  I decided to replace all of them.

Rerouting the Overflow Tube

I decided that I could disconnect the existing overflow tubing and substitute a longer one which would pass over the fresh water tank to the driver's side, then pass down to under the motorhome in the closed area of the compartment which houses the dump valves and holds the outside water fixture and filter.  This would be pretty much totally hidden from normal view.

This is the original overflow plumbing.  Water can slosh to this end of the tank during a left turn and run right
out to the ground.

I bought a new length of  tubing and routed it over the top of the tank to the driver's side.  It was a tight
fit getting past the mass of hoses and cables running fore and aft, but with a protective length of 2 x 4 with
a wide, deep groove cut to protect the tubing, it all fit.

The tubing drops down to a PVC pipe which passes through the floor.  This is the dump valve compartment
and cannot be seen normally.

This is where the pipe exits under the floor, well away from any structure, especially the rear bulkhead.

Valve Replacements

I have always been wary of the ball valves in my system.  They are a crimped copper construction and I had an early failure of the one in the bathroom which controls filling the fresh water tank.  I replaced it many years ago.  Looking at the remaining valves I found one that had obviously been leaking with rust staining, and another which did not seal after I operated it.  I bought all new brass body ball valves and replaced all of the original ones.

The left picture shows the water tank shut off valve.  It is rust  stained and has obviously leaked at some time.  The right shows the new one.
In all cases I was able to cut one end of the PEX tubing, moving the valve over somewhat, then connect the other end with a new piece of PEX.
I made good use of the manual crimper (tighten two bolts to crimp) I bought when I replaced the first valve years ago.

The various drain valves looked in better condition, but one of them would not shut off tightly after draining through it.  I am much happier now
with all new valves.

When the hot water heater failed, there was no valve to shut off the water to it.  Now there is!

Hot Water Heater Replacement

The failure of my hot water heater is what started all this updating.  Replacing it was a fairly routine procedure except for three areas:  

1.  I think it was originally installed before the water tank (or maybe the floor above), as the fairly stiff  PEX tubing connects directly to the input and output fittings.  When pulled out enough to access these fittings, the PEX is warped and under a lot of strain.  Removal was not much of a problem, with the tubing snapping into its relaxed position once the fitting was unscrewed.  Replacing it was pretty much impossible!  I was not able to put enough pressure on the tubing in the right directions and give it the right twist to engage the fittings.  I ended up cutting off the PEX about where it entered the water heater compartment and connecting it to the water heater with flexible stainless steel braided tubing.  That made it easy!

2.  The new unit supposedly is a replacement for the older one, except the dimensions are just very slightly larger.  Foretravel welded a snug fitting
steel mounting frame to hold the water heater and the new one would hang up when trying to fully insert it.  I had to use my angle grinder and clean up any welds that went just slightly into the opening along with one surface bar that went about 1/16 inch inside the square tubular welded frame.  A little black paint finished it, then it just fit.

3.  The new models use a different control system for the electrical heat.  The original system just wired the heater element through a separate in-heater thermostat to the AC switch at the foot of the bed.  The new system intends the AC to be connected continuously and a built in 12 volt relay is controlled by a panel switch along side the propane control.  This is a nice system for a new installation, but I have a fully wired system for the old unit and do not want to rewire the coach for this system.  I briefly considered modifying the water heater so the relay contacts are connected all the time, but it appears they use this relay with their integrated thermostat to maintain the temperature.  Some of the comments on RV plumbing forums say to just connect the control wire to 12 volts and control the AC normally.  I do not want to have a continuous load on the 12 volt batteries, so I decided to add an AC outlet to the switched heater power and plug in a 12 volt "wall wart" power supply.  This way, when the bed switch is on, the 12 volts turns on and supplies power for the control relay, and also supplies the AC to the heater element.  When the switch is off, there is no power being drawn at all.  Problem solved!

Here I have installed a new AC outlet box connected to the original heater wire.  A new wire now extends
to the water heater.

When I removed the water heater, I clamped the two engine coolant hoses flat to keep the coolant from running out as I unhooked the hoses.  When
I reinstalled the hose, it kept kinking where it needed to make a sharp bend to clear the water tank.  I solved this by winding a spring from some
stainless wire I had and putting it over that portion of the hose.  No more kink.  On the right, the flexible hoses I added would not bend sharply
enough for one of the fittings, so I had to install a street ell.

When the heater was all connected and back in place, there was just enough room for all the hoses wires and
new equipment as shown by this shot looking upward behind the heater.  (The water tank is on the bottom and
 the heater on the top.)  This view shows the 12 volt power supply plugged into the AC outlet.

The final installation looks just like it belongs.  I like the new white door; I think it looks a lot better
then the old flat black one!  Of course the important thing is that it all works - and has no leaks!

R. S. Mason    Prescott AZ,    February 2017