Electronic Modulation Temperature Controls
For Energy Recovery Units without Temperature Control Package
A Discharge Temperature Dial is used for temperature control for electronic modulation. The temperature dial will be located in the furnace control center.
For Energy Recovery Units with Temperature Control Package
The Temperature Controller in the unit’s main control center will provide the electronic modulation control.
High and Low Fire Settings for Electronic Modulation
Check the high and low gas pressures on initial start up per the instructions below. These settings are
Modulating Valve
Low fire adjustment
B
Combination Gas Valve
High fire adjustment
Figure 5: Electronic Modulation Valves
A
1.Set the unit to high fire by placing a jumper between terminals 7 and 8 on the Maxitrol amplifier.
2.Measure the burner manifold pressure at each furnace at the pressure test port (see Figure 2) using a high quality manometer that can measure low gas pressures. The pressure at high fire should be 3.5 in. wg for natural gas and 10.0 in. wg for LP Gas. To change the pressure, adjust the high fire screw on the combination gas valve.
3.To get the unit to low fire: Remove the wire from terminal 3 on the amplifier and isolate it from touching anything. Set the discharge temperature selector to the highest setting. If there is a room override thermostat, turn the dial to the highest setting.
4.Measure the manifold pressure on low fire, it should be 0.88 in. wg for natural gas and 2.5 in. wg for LP gas.
5.To adjust the low fire, remove the bypass cap (A) and turn screw (B) as shown in diagram. Adjust the screw indicated in Figure 5 on the modulating valve.
6.Reconnect wire to terminal 3.
7.Remove jumper and place all wires back to where they were and plug the manifold pressure port.
6
