Tuesday, October 16, 2007

No more water.

The Fuso Szulc condemned the proud owner this morning to become a mechanic again.
The water pump stopped working.
No more water.

Fervent and loyal blog readers, and there are hundreds of them, will remember that frequently there has been reports of faltering water service in the Fuso Szulc.

The first problem was the vents in the water tanks.
They had been made in a way that when the two water tanks were filled up, while driving 40 % of the water was lost leaving the tanks by the vents.
The photographer himself corrected this problem by blocking 4 of the 6 vents and routing the remaining 2 to the vent opening next to the filling mouth.

The first water pump, an ordinary Shurflo, had this strange habit of sometimes running permanently without that a faucet was open.
And the water flow was often minimal.
Therefore, a Shurflo Extreme 5.7 replaced this water pump.
That resulted in an improvement in water quantity coming out of the faucets and shower and considerably less noise.
But repeatedly the pump wouldn’t work.
By switching it off and on, it would pump again.

Next adventure was that the monitor of the SeeLevel ll was blown up by the high amp draw of the pump.

This morning again the water pump would not work and the power cable was connected and disconnected a few times.
As usual.
But this time it blew the fuse of the Shurflo Extreme 5.7 water pump.

The fuse was replaced and an enigmatic behaviour resulted.
The pump would work but go dead when a faucet was opened.

Working on this problem it was noticed that the water strainer had a plastic transparent container.
Through it was seen the absence of water.
Absence ?
In this way it was discovered what could be the reason for all this trouble with the water service since the Fuso Szulc came out of the hangars of Santek Trailers in Riverside, California, USA.

The exit hose for the water from the tank is of course at the lowest point of the tank.
It is important to know though that this water tank is mounted underneath the floor of the camper.
This means that the exit point is about 40 cm (16 inches) lower than the floor.
The exit hose however is going up because the water strainer is mounted against the floor.
Next, behind the strainer, the hose goes a little down and up again because also the water pump is mounted against the floor.
This means that the water has to go up 40 cm (16 inches) to reach the water pump.
The question is if that matters.
In most RV’s the water pump is mounted on top of the floor and that is exactly also the lowest point for the water tank.
Because in ordinary RV’s the water tank is on the floor: not underneath the floor.
In other words, the water flows by gravity into the pump where it is being pressured into the water pipes of the RV.
The Fuso Szulc has this max 40 cm for the water pump to conquer.
But can and will a RV water pump besides pressurizing water into the waterpipes also pump up water that is 40 cm lower?
Maybe a fervent and loyal blog reader knows the answer to this question.
It cannot be found on the Internet…

What was also noticed was that now that the water tank is at about 64 % capacity, the water in the hose from the strain down to the tank flows back to get to the level as is in the tank.
Because the drain is mounted against the bottom of the floor, this drain is in fact on a level where the water is when the tanks are 100 % full.
It seems the water pump doesn’t keep the water in the hose.
When the pump stops the water flows back down 40 cm lower into the tank.
Next time the faucet is opened, the pump has no water and the system contains air.

Probably this explains why the first water pump was often running without a faucet open.
There was no water coming to the pump by gravity.
And it explains the story of the second water pump: not getting water it overworked using so many amps it blew up the Seelevel Tank Monitor and today the fuse.

As a temporary solution the strainer has been dishooked from the floor and brought to a much lower point.
To avoid the water in that part of the hose flowing back into the tank.

Until now that seems to work.
The faucets give water.

But there are still questions….



Al said...

I had a problem posting a comment on your blog page,
so I am resending the comment this way.

It sounds as if there may be an air leak in the line
or the connections between the water tank, strainer
and the pump. It could also be a bad check valve in
the pump.

The solution I would use, place the pump as close to
the same height as the tank bottom as possible. This
will keep the water against the check valves and
eliminate the need to pump air until the water gets up
to the pump. Do not put anything between the tank and
pump, put the strainer after the pump.

If this solves your problem, then you can later insert
the strainer between the tank and pump. This may
reduce the water flow rate at the faucet compared to
having the strainer after the pump.

If this exposes the pump to being hit by debris while
driving, use a plate of metal or wood to protect the


Mandira said...

I think that the fact that the water pump is not working is that sign you were waiting for. Time to break up the camp and flow with the wind!
What I have learned recently is that everything passes, not only bad things, but good thing too.
And maybe it is good to have a few ideas not materialized, so that they will keep you busy, and later you will find some new solution to give them form ...
If you choose to stay longer - a tip for your walks: begin walking or running first against the wind, so that the second part would be easier. We always do so when go walking on the beach here. The only difference is that here the direction of the wind is not constant as it in your case.

Anonymous said...

I found on the Shurflo product page at http://www.shurflo.com/pages/RV/rv_categories/potable_water/extreme.html is a PDF specification sheet that states that the prime for this pump is 2.7m. So it should handle the distance it is now from the tank.
The other commentors suggestion to check the check valve is a good one. Here I would suggest that if the problem only occurs when your water tanks are at or below a certain level, then it is most likely a check valve problem.

The check valve is there to make sure that there is a minimal amount of water in the pump at all time. If it is leaking then the pump has no water in which to start the priming with, and therefor may not be able to draw water of the distance. Compared with a good check valve that keeps water in the pump, so that when it starts to pump that creates a vaccuum which helps pull water up to and into the pump. This is why the commentor also suggested a possible air leak, which would not allow for the vaccuum to build to the sufficient level.