instant water heater dc water pump help.

Thread Starter

solac

Joined Aug 13, 2015
17
hi,

Need help on switching ideas for instant water heater that has float switch to turn heater on. So the problem is i added a 12v d/c pump, was hoping to tap on the float switch to turn on the a/c d/c converter to power the small 12v pump. as soon as i tap on the a/c d/c converter the switch contacts gets welded together because of spark(arc). tried adding a home made snubber with .1uf and 120ohm resistor in parallel to the a/c d/c converter lines and didn't seem to help at all. so i have installed the pump and the reed switch is already busted with no way to use both. when i turn on the water valve. I will be replacing the reed switch once i get a replacement. but am lost to how to turn on the pump simultaneously when the water heater turns on.

thanks
 

MaxHeadRoom

Joined Jul 18, 2013
21,609
If using a reed relay to switch a motor, you are most probably exceeding its current rating, use a small relay to switch the motor, picked up by the reed relay.
Max.
 

crutschow

Joined Mar 14, 2008
25,640
If you drive the coil of a mechanical relay with the reed relay, be sure and add a diode across the coil (cathode to positive) to suppress the arc from the coil, otherwise that could also zap the reed relay.
 

Thread Starter

solac

Joined Aug 13, 2015
17
Hi. I have added a relay and seems to work just fine. I completely isolated the pump from the water heater circuit. But the relay is still swtiched on by a reed switch that i have added.
 

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