Testing the heaters

Each heater has been individually checked at the factory. However each heater should be field checked by measuring cold resistance for confirmation with label wattage. After heater installation, the entire circuit should be tested, to check the on-sight electrical work.

Two methods of testing will be discussed in the following paragraphs.

Full Power Available - Apply rated voltage to the heater load circuit. Branch loads are to be read with a suitable amp meter. The amp meter value should be the same as that calculated for the heating load and, if the values agree, all panels are operating. If the values do not agree, installation should be re-checked. For physical check without a meter, it is only necessary to feel, but not touch, the heaters.

Without Power Available - This check of the heater installation requires the use and knowledge of an ohmmeter. A resistance measurement is taken at the load circuit, with all other circuits isolated. This will give the total resistance of the heater load. Knowing the total heater load of the panel in watts and the heater rated voltage, a simple calculation will give the same values as that read on the ohm meter. (The same test procedure applies of an individual panel) Example: For a branch circuit of 1500 watts and panel rated voltage of 240, the resistance will be 38.4 ohms: