Ranco Controller


New member
I set up my ranco controller. Im pretty sure its a faulty controller, but i cant return it, so figured I would ask here.

this is a single controller, when i switch the temps or the H1/C1 i can hear the internal contacts switch positions. but no power is going to my N.O or N.C at all, no matter what i set the temp at, on either H1 or C1. ive tried it all.

here is how i got the controller set up.


-if you know anything about this problem, let me know.



New member
does not mean the heater is on till it hits 80, just that the heater has power.. this way if something goes south with the heater and it automatically stars heating past the setpoint on the heater, when the contacts shift the heater power will be disconnected.


Premium Member
Two items to take note of:

1) Setting a heater and a chiller on opposite sides of a relay is going to cause them to fight at the setpoint and waste a LOT of energy and cause a lot of undue hardship on the chiller. That is what TWO stage controllers are for.

2) The COMMON terminal of the relay needs to be fed with 120VAC. That is what powers the NO and NC contacts. The other power connection is what powers the controller itself :)


New member
thats my problem. common is being fed with neutral i think (not at home)


thanks bean. stupid rookie mistake on my part. (i really didnt even want to admit that, but ohwell)

as for the fighting.. I completly understand what your saying, but i dont think it relates to me, sorry again if im wrong, but..

"the heater" is just a stealth heater, and will be set at 76. so it should turn off at 76-77. the ranco will turn off the power to the whole heater at 80-81.. so Logically.. the heater should already be off anyway.

also.. i have no need to run the heater during the summer months, and no reason to run the chiller after i can turn off my AC and it not get hotter than 78 in my apartment.

-like i said, i think this will work and there will not be any chiller/heater fighting going on with that much of a gap between temps.