double float switch??

[GHA]

Is there such a thing off the shelf anywhere?

It's to switch a bilge pump in a deep bilge where a normal switch just ends up in the pump cycling as the water drains back down the exit pipe lifting the switch which fills up the pipe again......

Tried a search but nothing much came up.

A double float switch, one above the other into a latching relay should do the trick.

If such a thing exists....

 

[Graham_Wright]

Raise the float switch?

Edit Sorry that was stupid! Didn't think.

Edit again. What you need is a large hysteresis. Without thinking it through (again), if you can, what about increasing the float switch lever length. But you may have insufficient room.

 

[GHA]

Raise the float switch?

Makes no difference. Just means the pump would cycle with a bit more water in the bilge, when the switch goes OFF, the water in the pipe runs back into the bilge raising the level enough to switch the float switch on again.
Not sure a one way valve would help either, probably just slow the cycling down a bit.

 

[Hadenough]

http://www.waterwitchinc.com/new/literature/MINIWWrevI abyc.pdf

One of these fitted high enough to stop the cycling perhaps. Can't agree thought that a non return won't work, I have one in a deep bilge and it doesn't cycle.

 

[Graham_Wright]

This is a common problem meaning you can never have a completely dry bilge. With shore power, my answer (but no for your case) is to use Mr Wilks wet and dry vacuum cleaner. Has been known to find the odd spanner as well!

(Please read twice edited original answer).

 

[GHA]

http://www.waterwitchinc.com/new/literature/MINIWWrevI%20abyc.pdf

One of these fitted high enough to stop the cycling perhaps. Can't agree thought that a non return won't work, I have one in a deep bilge and it doesn't cycle.

Cheers loads for that. Delay!! Of course! Didn't think of that, shouldn't be too hard to make one, 555 chip or something.

Don't really like the thought of anything extra like a valve on the way out so will pursue an electric route first.

Ta

 

[GHA]

This is a common problem meaning you can never have a completely dry bilge. With shore power, my answer (but no for your case) is to use Mr Wilks wet and dry vacuum cleaner. Has been known to find the odd spanner as well!

(Please read twice edited original answer).

To be honest the bilge pumps never run, benefit of a steel hull. Which is fine if you're onboard a lot just in case but leaving it on a mooring for a while needs something a bit more robust.

 

[winsbury]

Is there such a thing off the shelf anywhere?

It's to switch a bilge pump in a deep bilge where a normal switch just ends up in the pump cycling as the water drains back down the exit pipe lifting the switch which fills up the pipe again......

Tried a search but nothing much came up.

A double float switch, one above the other into a latching relay should do the trick.

If such a thing exists....

See this thread - several ideas and a circuit I proposed that has hysteresis which solves that exact problem http://www.ybw.com/forums/showthread.php?334855-No-more-cheapo-float-switches/page4&highlight=bilge+pump+switch

 

[GHA]

See this thread - several ideas and a circuit I proposed that has hysteresis which solves that exact problem http://www.ybw.com/forums/showthrea...at-switches/page4&highlight=bilge+pump+switch

Ta
I have a latching relay knocking about already, the twin float was the bit needed. thanx

http://www.ebay.co.uk/itm/160804066289?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

 

[winsbury]

you're welcome, but how do you propose to do it with a latching relay ?

 

[NickRobinson]

Consider using a washing machine pneumatic switch.
It is adjustable, can cope with enough current not to need relays, latching or otherwise.
There is good separation (hysteresis) between on and off so no cycling and all you have near water is a small bore pipe with a plenum (to create the volume needed to switch) Wiring can be high and dry.
Free too-
Nick

 

[GHA]

you're welcome, but how do you propose to do it with a latching relay ?

Can't remember
Might have been the lower float powered the relay then the upper float set it, so it stayed set until the lower float killed the power. Or maybe the lower float was the reset.