I am trying to create some redundancies for a small commercial ice maker to prevent there from ever being a flood in my garage. The ice melts from the ice bin (which holds around 80lbs of ice) constantly and gravity drains from 3/4" PVC into a condensate pump a few inches away… If/when the condensate pump fails, I plan to have a float switch open, breaking the connection at the DPDT relay and turn off the ice maker (to prevent more ice than what is already in the bin from being created) as well as close the newly installed inline motorized Taco zone/ball valve. Any melting ice will then stay in the ice machine with the valve closed. The Taco valve would also close in a power outage (being that the valve is N/C) so that the ice did not end up melting and draining with no power to run the condensate pump.

Planned install: The c & w/y terminals on the Taco valve would be wired directly to a 24V transformer. The two end switch terminals on the Taco valve would be wired to one of the common and one of the normally open terminals on a DPDT Relay (which is controlled by a 24V normally closed float switch). When the float switch activates (opens), the Taco valve would close. In the event of a power failure the Taco valve would close. See crappy diagram I made below.

So I think I have that all correct, but was wondering if I should try to build in a 2nd float switch to prevent any chatter at the motorized ball valve and not sure if there would be negative consequences if the ice machine ever received 'flickering' power? I think the situation I would need to worry about the most is an extended power failure that turns the ice in the bin to water... When the power comes on, I fear the condensate pump would have trouble keeping up with a mass flow of water (although it is a 270GPH pump with 1G tank). My assumption is there would be several 'trips' of the float switch as the pump worked to remove all the water. My thought was installing low and high float switches on the condensate pump. The ball valve would close and ice machine turn off when both switches were open and the ball valve would open and ice machine turn on when both switches were closed. Not sure how that would be wired though???

My other thought, and this may actually be a better solution is to just use one float switch, but if the float switch ever opens it would essentially 'trip' the circuit (closing the ball valve and turning off the ice machine) and require a manual reset. This really seems ideal to me as someone would have to be present to inspect why the float switch was triggered... I have absolutely no idea on how to best implement this (with my limited electrical expertise). I've seen latching relays mentioned from Google searches, but I am unfamiliar and not even sure if that would be the best approach. Any ideas on how to accomplish this would be very helpful!!!


Normal state - Ice machine powered, NC motorized ball valve powered.

High float state - Ice machine no power, NC motorized ball valve no power.

Notes - Store the high float state if triggered. After high float state is triggered, require a manual reset before the ice machine and motorized ball valve receive power again.

FYI: Ice machine pulls around 5-6amps at 120V. Ball valve does around max .5 amps at 24V. Planning on also using the 24V transformer for relay(s).

Basic wiring diagram

  • \$\begingroup\$ I can't read the essay, it's too long. I don't even find a question. \$\endgroup\$ Commented May 21, 2021 at 20:07
  • \$\begingroup\$ I want to add a reset button that would need a manual press if the float switch ever opened. I found this with some searching, which seems interesting... chicagosensor.com/HighLowLevelApps I was thinking I could replace the bottom float switch with a NO momentary toggle... But then every time the power was lost, even for a second - wouldn't I need to use the reset button? I would only want to reset if the float switch was actually opened... Otherwise every time there was a thunder storm, my ice machine would be turning off... Is there an easy way to accomplish this? \$\endgroup\$
    – Talsma
    Commented May 21, 2021 at 20:28
  • \$\begingroup\$ Can you find a level switch with some hysteresis? For example, opens when level gets to say 80%, doesn't close again until it drops below 20% \$\endgroup\$
    – Theodore
    Commented May 21, 2021 at 21:39
  • \$\begingroup\$ Could you use a float switch as used to control a bilge pump in a boat? \$\endgroup\$ Commented May 22, 2021 at 15:28

1 Answer 1



simulate this circuit – Schematic created using CircuitLab


simulate this circuit

This is what I could understand from the essay.

1st diagram:

Two float switches NO contact - if the water is present then the contact is made. First the LO Lev is on, then after accumulating water even the HI Lev turns on. At that time RLY1 is engaged which turns on the valve and the second relay RLY2 which cuts the power off to the fridge. One contact of the RLY bypasses the HI Lev, so even if the level drops below HI Lev, the RLY1 is self-sustained until the level drops below LO Lev.

2nd diagram:

Everything the same, except it has a Reset button NC in place of LO Lev. The whole state is reset only after button press.

NOTE: You need two searate relays to switch 24V and 120V, as they are different potentials. The relay's contact spacing is too little to have a safe isolation in between.


2nd try:

The Hi Lev switch engages the relay that is self-sustained while the power is present. If the water level is high the power is cut off to motorized valve and to the fridge. You can reset this state by simply removing the power after the water has been manually drained.


simulate this circuit

3rd variant (the one you are asking for, I guess):

Level switches are NC type. When the water level is below LO level, then the valve is powered on and the fridge as well. It stays such until the water level reaches the HI level. At this point fridge and valve are cut-off. They will turn on again only when water falls below LO level . The same rule applies if a power outage occurs.


simulate this circuit

  • \$\begingroup\$ Thank you for taking the time to help!! The NC motorized ball valve should actually be powered during normal use so that it stays open and able to drain the ice maker. It should be closed when the high float switch is activated so that no more water is able to drain from the ice machine. Other than that this appears to make sense. Would you be able to fix that? I believe a brief power outage would essentially act as a reset, but I don't think it would leave me in a state with no power and a closed ball valve like an outage would with this model: chicagosensor.com/HighLowLevelApps \$\endgroup\$
    – Talsma
    Commented May 22, 2021 at 2:09
  • \$\begingroup\$ @Talsma Can you edit your question and ask a straightforward question, very short form with essential details Normal state: motorized valve is powered, fridge?? ; Hi Float state: motorized valve cut off, fridge?? On which level you need to store and reset? \$\endgroup\$ Commented May 22, 2021 at 8:17
  • \$\begingroup\$ I think your second try (i.sstatic.net/mb5LI.png) accomplishes what I was asking for. I would just add the NC reset button back for ease of use. I was simply commenting above that a power cycle would be the same as a reset button, but I believe a reset button is a more elegant solution. I'll go back and edit my original question to be more concise. THANK YOU SO MUCH FOR YOUR HELP! \$\endgroup\$
    – Talsma
    Commented May 22, 2021 at 13:31
  • \$\begingroup\$ @Talsma If that solves your question, you can accept it and close the thread. \$\endgroup\$ Commented May 23, 2021 at 20:49

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