Frequently Asked Question

How to install the unit heater / circulator box? What do "NO" and "NC" mean?
Last Updated a year ago

This unit is constantly powered via a 230 VAC supply and the central unit sends it its relay open or closed position when the control decides that it is time to heat or not to heat.

The Snugr heater control box can have 2 relays (R1 and R2) which are both linked to the same room and will be controlled at the same time.

Three contacts are available for the control of the unit heater:

  • one common: always connect
  • one NO contact (Normally Open)
  • one NC contact (Normally Closed)

Connect one of the two wires of your heater to the common contact.

For the second one, two possibilities:

  • If when the heater is not connected to the Snugr heater control box and the two wires are not bridged (i.e. not connected together), the heater is not producing heat, then connect this second wire to the NO contact (normally open). This means that with its contacts normally disconnected, the unit heater is not producing heat. When the relay on the Snugr heater control box closes, the heater should start to heat.
  • However, if the two wires of the heater are not connected to the Snugr heater control box and are not bridged, the heater is already producing heat. So use the NC (NF) (normally closed) contact for the second wire connection. The unit will then open, unbolt the relay to disconnect the two control wires when the system wants to request heat.

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