Shower box

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SolentPhill

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For some time I have had an issue with this thing. This is the one with a bilge pump and float switch, I know where the problem is and have made a temporary repair but now it's caught up with me.

The problem as far as I can see is that the outlet is higher than the box, so as water comes in, it kicks in but slowly water runs back into the box so it kicks in again and so on. I put a one way valve in and it worked ok, but a few months and a few swmbo hair washes and the hair gets through the filter and sticks in the one way valve holding it open. I can't raise the box and dont really want to put another outlet on side of boat, and if I did it would still be higher than the box.

Has anyone else experienced this and if so how did you sort it? and I don't mean the hair washes.
 
SolentPhill said:
For some time I have had an issue with this thing. This is the one with a bilge pump and float switch, I know where the problem is and have made a temporary repair but now it's caught up with me.

The problem as far as I can see is that the outlet is higher than the box, so as water comes in, it kicks in but slowly water runs back into the box so it kicks in again and so on. I put a one way valve in and it worked ok, but a few months and a few swmbo hair washes and the hair gets through the filter and sticks in the one way valve holding it open. I can't raise the box and dont really want to put another outlet on side of boat, and if I did it would still be higher than the box.

Has anyone else experienced this and if so how did you sort it? and I don't mean the hair washes.
Click to expand...

from bilge + float switch installation experience, it seems that what you have to do is have a siphon on your outlet pipe, i.e. make sure the pipe off the box goes straight(ish) up to higher than the outlet and then drops down and out. So once it kicks in, it empties the contents and on switching off, there's only a bit of water to drop back in rather than the whole length of tube to the outlet and not enough (hopefully) to trigger the switch again ;)

V.
 
I have a similar setup (no one way valve), but it doesn't cycle with water running back into the box.

I'm not sure, but I think either your pump is weak, or the float switch isn't operating at the right positions (start and stop). Also check the routing of the pipe.
 
virtuvas said:
from bilge + float switch installation experience, it seems that what you have to do is have a siphon on your outlet pipe, i.e. make sure the pipe off the box goes straight(ish) up to higher than the outlet and then drops down and out. So once it kicks in, it empties the contents and on switching off, there's only a bit of water to drop back in rather than the whole length of tube to the outlet and not enough (hopefully) to trigger the switch again ;)

V.
Click to expand...

I tried that, I got the same size pipe and a joiner and put a u in it. But being a 1/2 ID pipe there enough water from the top of the u to run back and start the pump.

The pump is 800 gph, so it's plenty powerful
 
SolentPhill said:
I tried that, I got the same size pipe and a joiner and put a u in it. But being a 1/2 ID pipe there enough water from the top of the u to run back and start the pump.

The pump is 800 gph, so it's plenty powerful
Click to expand...

hm, so check as FP suggests the float switch. Changing the angle a bit could mean that the extra water coming back wont be enough to trigger it again. Or the switch is a bit old and more/less sensitive than it should. It's really a case of having to go further up to trigger on state and on dropping down will trigger off state at a substantially lower angle. If it doesn't, check how it's secured or if the whole box is slightly slanted or something...
 
You could try and connect a small diameter outlet hose. Say id 10 mm. That way the pump will need longer to empty the small tank but the returning amount of water will be minimal and not trigger the switch.
 
SolentPhill said:
Right by raising it up a bit it would need more water to trigger it.

That may work.
Click to expand...

By raising the float switch you will also make it switch off earlier leaving more water in the box so it will not help. It's the volume of water in the pipe that is the problem.

Fitting an electronic type of float switch that makes the pump run on for an Extra few seconds would sort it or having a larger capacity sump box (larger in width/length not height)

Was it a duck bill type of non return valve fitted?
 
I still think the problem is the float switch. But not the position.

If the volume of water that runs back down the pipe causes a change in position of the switch that is greater than the difference between the "on" and "off" positions, then it will cycle.

On mine, it needs a couple of inches of water to trigger it, and stops with half an inch or so left behind.
 
I had exactly the same problem on the shower tray on my previous Brooms. The one way valve in these units are a cheap piece of neoprene and it's impossible to get just the replacement piece. I tried cleaning and refitting but it never lasted long so I bought a decent quality one way valve unit similar to below:

http://marinestore.co.uk/MTLV121.html

I fitted this a few inches along the outflow pipe and it stopped the problem completely.
 
The non return was spring loaded, today I bought a jabsco one.

The float switch was the original one that comes in these boxes, it is screwd down with 2 screws front and back so its secure with no adjustment.

I thought a custom made bigger box maybe an answer,
 
FlowerPower said:
I still think the problem is the float switch. But not the position.

If the volume of water that runs back down the pipe causes a change in position of the switch that is greater than the difference between the "on" and "off" positions, then it will cycle.

On mine, it needs a couple of inches of water to trigger it, and stops with half an inch or so left behind.
Click to expand...

I agree with FP. If pipe flowback volume > float switch trigger volume then cycle. On the face of it, there are two solutions - the simple one is a box with a bigger floor area - so the volume of water required to trigger the float switch is greater; the alternative would be to fit a different float switch to increase the range over which the float switch operates (eg if it's one of those float switches with an arm, make the arm a bit longer and that would do the trick).

Cheers
Jimmy
 
I have had this a few times on different boats. The problem is that the pump, hose, box and switch create an oscillator. The volume of water that runs back slowly is enough to retrigger the pump in an endless cycle. To stop it you have to change either the volume of water that runs back by shortening the exit hose or increasing the volume of the pump box.

On a previous boat where this drove me mad I solved it by buying a cheap plastic box from staples/b&q that was @ twice the volume of the shower pump box. Then you put the entire shower pump out box in it with the addition of a new hole in the side of the shower pump box so that incoming water flows into the show pump box and the extra volume of the new box. float switch will work as before but when the pump goes off the returning leak back water will be insufficient to trigger the float switch.
 
kashurst said:
On a previous boat where this drove me mad I solved it by buying a cheap plastic box from staples/b&q that was @ twice the volume of the shower pump box. Then you put the entire shower pump out box in it with the addition of a new hole in the side of the shower pump box so that incoming water flows into the show pump box and the extra volume of the new box. float switch will work as before but when the pump goes off the returning leak back water will be insufficient to trigger the float switch.
Click to expand...

Now thats a good idea thank you.
 
Last edited:
just a matter of interest how big a hole 1 meter under the water line would a 800 gph pump handle say with a displacement of 8 tons,i do not know the answer but belive it is very small/ish
 
rib said:
just a matter of interest how big a hole 1 meter under the water line would a 800 gph pump handle say with a displacement of 8 tons,i do not know the answer but belive it is very small/ish
Click to expand...

This box is from the shower, so as you use any of the sinks or have a shower it goes into this box, and empties as it fills.
 
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