Float switch top-off with relay?

[Cresta]

I have two float switches to control top-off level in my sump. One is for the actual level to start the refill pump. The second is a backup to cut the circuit in case the first float switch gets stuck.

After using the setup for several months, both switches failed together causing a small overflow.

I hooked up a powerhead directly to the float switch running off AC current. The plastic float switch is rated for 15A purchased from Grainger. However, I've heard that this is not safe at all, supposedly, the float switch can't handle direct AC current and will get stuck. Is this true?

How do I hook up a relay to the circuit to make the system "low voltage"?

Also, I want to add a timer relay to the circuit. In case both flow switches fail again, I want the timer to only permit refilling for 5 minute and delay the pump from continuous operation. I know there are timer relays used in air conditioning units. Those relays prevent the AC compressors from flipping on/off constantly. Any suggestion for a cheaper solution?

Thanks in advance.

 

[Anonymous]

I would wire the two float switch in series and keep them at the same level. That way both float switches have to be calling for water before your pump get's activated. If either fails you don't get a flood. The way you have it now, if your "off" float fails you are screwed. Also if your "on" switch fails you get no water. This is not fail safe at all. In series is fail safe against a flood, but not fail safe against low water condition.

A simple 120V to 12V transformer can get the low voltage that you are looking for. These can be found at Radio Shack. Mount the transformer in a PVC box in your stand.

Your float switch is most likely more than capable of handing the small current of your powerhead.

Louey