Water level & float controller - how to?

[Frothy]

Hi All

Does anybody use the stainless float switches in their brewery?
I'm intrigued as I've been looking for ways to control the liquor level in my HLT and mash tun over the years and these seem to have really dropped in price recently.

How have you used yours and how to go about wiring them?

I've thought about fitting one so that when I'm pumping hot water from my HLT to the mash tun during fly sparging - it will cut the pump once the mash tun is full.
As the switch is on/ off it seems that I would have to fit it upside down so that it switches off when the tun is full. Interested to see what others may have done.

cheers
Frothy

[themadhippy]

As the switch is on/ off it seems that I would have to fit it upside down so that it switches off when the tun is ful

or use the float switch to control a relay

[scotia]

I fit high low level switches to the HLT's I build as standard, one to stop the flow of water when filling and the other to save the element in the event of the vessel running dry when switched on. I also use them on the underback to save the pump from running dry and switching the pump on when it reached a specific level. http://www.pvl.co.uk/level_switches_sta ... witch.html

[Frothy]

Thanks so far,
Scotia that's very similar to the switch I picked up.

MadHippy I like this idea - I take it you mean that when the switch gets up to the on position (and the mash tun is full) it will effectively switch the relay off and cut the power to the pump.
Will this require any special type of relay? i.e. an off action rather than an on?

cheers

[Cazamodo]

I plan to implement one in my control panel, where I will have a relay controlling power to the heating elements. Thsi relay will not switch on, until the float switch is on, to save me forgetting to turn the elements off when sparging below the element level in the HLT.

[Fil]

bear in mind im no sparky Frothy,
What u implement depends on what pump it is your going to switch on and off.

compare the power usage of the pump to the limits of the float switch, if within the capacity of the switch to handle without a relay dont bother with one.
power is rated in amps as limits on switches but devices are generally rated in watts, google an easy tool to convert if needed.. for example a 3kw or 3000w device like an element will draw about 13amps of power on a 240v circuit so would need a switch rated at higher than 13a for a safe circuit, probably 15-20a to be thoroughly safe....


if you have a 12v dc pump i think you could just wire up a simple circuit with the float switch cutting the pump power directly. but check the max voltage and amperage of the switch first..

If like scotia you have the mains powered chugger pumps (drool) or something else that draws more power than the float switch can handle then yep look at relays, bearing in mind its a slightly more complex wiring involving 2 circuits, a power circuit for supplying the pump with power and a low volt dc control circuit within the float switches rating to supply the switching current activated by the float switch.. now one of those old phone chargers in the back of the drawer kicking out 5v dc will come in handy after all..

[themadhippy]

compare the power usage of the pump to the limits of the float switch, if within the capacity of the switch to handle without a relay dont bother with one.
power is rated in amps as limits on switches but devices are generally rated in watts, google an easy tool to convert if needed.. for example a 3kw or 3000w device like an element will draw about 13amps of power on a 240v circuit so would need a switch rated at higher than 13a for a safe circuit, probably 15-20a to be thoroughly safe..

.
if were talking elements or DC then the above is correct,however if talking AC pumps things get a bit more complex due to the high inductive nature of the load.A 10A switch may only be rated for 2A on an inductive load.Also the old power=volts x amps formulor that was drummed into us at skool isnt true,the correct formulor is power = volts x amps x power factor,so that 240w motor might draw 1.25a instead of the expected 1A,you also need to take into account the intial start up current of the pump motor,that can be up 6X the normal running current

or something else that draws more power than the float switch can handle then yep look at relays, bearing in mind its a slightly more complex wiring involving 2 circuits, a power circuit for supplying the pump with power and a low volt dc control circuit within the float switches rating to supply the switching current activated by the float switch

if the float switch can handle 240v theres no reason to use a low voltage control circuit

[aamcle]

240v near liquid is not a good idea, that's what 12v is for.


ATB. Aamcle

[themadhippy]

a - I take it you mean that when the switch gets up to the on position (and the mash tun is full) it will effectively switch the relay off and cut the power to the pump.
Will this require any special type of relay?

something with a changeover set of contacts will do, i likes these http://www.maplin.co.uk/p/round-base-10 ... 3pdt-jg62s as there easy to mount and wire.The float switch controls the relay coil.The relay switch has 2 outputs ,one on and one off and change over to off on when you put power to the coil

[Frothy]

epic thankyou - difficult trying to find this kind of relay, I keep thinking of "logic gates" from Physics back in the day.