Greenheck Make-Up Air Electric, Steam, Hot Water, Chlled Water, and DX Coils (457046) User Manual
Page 5
5
Troubleshooting:
Check-out Procedure:
1.
Equipment Needed:
a. Digital Voltmeter (0 - 20 VDC range) DVM.
Input for intended use. May be Thermostat (HCC - 10K) or other input such as 0 - 13 ohm, 0 - 20 VDC, 0 - 20
b. MA, 6 - 9 VDC, or 8 - 16 VDC.
c. Output relays (loads) for output stages or 200 ohm, 5 watt resistor.
2.
Wiring:
a. Plug in the required number of 2 stage PC boards for application.
(Stage boards always include two
stages.)
b. Connect output relays or 200 ohm, 5 watt resistor to provide output load.
c. Program Input Switch to ON or OFF for seven positions provided.
Electric Heater Sequence of Operation:
1.
120 Volt power from the control center (when supplied) or by others with out a control center, is delivered to
the electric heater for the step controller. This power must be interlocked with the supply fan, so when the
fan is off, the heater control power is off.
2.
A thermostat with a duct stat is supplied. The duct stat is placed in the blower discharge and monitors the
heated air.
3.
Electric Heaters are divided in to equally sized steps. For example, a 100 KW heater with 5 steps will have
20 KW per step. The thermostat and step controller will control these steps.
4.
A temperature and time delay of 0.7
o
F and 2 seconds, respectively, is standard for the controller. This is
designed to prevent unncecessary cycling.
5. With the thermostat set to 70
o
F the heater will be off with a temperature sensing above 70
o
F. As the
temperature varies the steps turn on and off to hold the setpoint discharge temperature. The colder the
discharge temperature becomes the more steps the controller will energize.
6.
In addition to the fan interlock mentioned in step 1, the heater has an airflow switch to prove that air flow is
established before energizing the steps. The heater also has an automatic resetting highlimit switch and
manual resetting highlimit switch set above the automatic switch to protect from overheating.