Energy Tech Laboratories DHG180, DHG240 Start Up, Burnercompartment, Limit Control Setting

035-17233-000-C-0702

IGN.CONTROL#2

IGN.CONTROL#1

	ROLLOUTSW.
SENSOR#1	GV1
	GAS
	VALVE
GV2	IGNITOR#1
GAS
VALVE

TABLE 16: LIMIT CONTROL SETTING

Units	Capacity, MBH		Limit
			Control
(Tons)
	Input	Output	Opens, °F
15 & 20	300	240	195
15 & 20	400	320	195

HEAT ANTICIPATOR SETPOINTS

It is important that the anticipator setpoint be correct. Too high of a setting will result in longer heat cycles and a greater temperature swing in the conditioned space. Reducing the value below the correct setpoint will give shorter ON cycles

IGNITOR#2

SENSOR#2

and may result in the lowering of the temperature within the conditioned space.

BURNERCOMPARTMENT

FIGURE 15 : GAS VALVE AND CONTROLS

3.Redundant Gas Valve - There are two separate gas valves in the furnace. Each valve contains a main and a redundant valve. The redundant valves are located upstream of the main gas valves. Should either or both of the main gas valves fail in the open position the redun- dant valves serve as back-ups and shuts off the flow of gas.

4.Flame Sensor Rod / 100% Ignition Control Lock-Out - The flame rods and controls are located per Figure 15. If an ignition control fails to detect a signal from the flame sensor indicating the pilot flame is properly ignited, then the main gas valve will not open. It will continue to try and ignite the pilot for a maximum of 85 seconds, then if the pilot flame is not detected, the ignition control will lock out furnace operation until 24V power is removed from the module either at the unit or by resetting the room thermostat.

5.Rollout Switch - This switch is located above the main burners in the control compartment which in the event of a sustained main burner rollout shuts off and locks out both ignition controls closing both gas valves. The igni- tion controls lock out furnace operation until 24V power is removed from the controls either at the unit or by resetting the room thermostat. Note the auto reset rollout switch must reset before allowing furnace operation.

6.Auxiliary limit switch (AUX) - This control is located inside the heat exchanger compartment and is set to open at 190F. It is a manual reset switch. If AUX limit trips, then the primary limit has not functioned correctly. Replace the primary limit switch.

TABLE 17: HEAT ANTICIPATOR SETPOINT

Gas Valve	1st Stage	2nd Stage
Honeywell VR8440
	0.30 amp	0.11 amp
White-Rodgers 36C68

START UP

PRE-START CHECK LIST

Complete the following checks before starting the unit.

1.Check the type of gas being supplied. Be sure that it is the same as listed on the unit nameplate.

2.Make sure that the vent and combustion air hoods have been properly installed.

OPERATING INSTRUCTIONS

This furnace is equipped with an intermittent pilot and automatic re-ignition system. DO NOT attempt to manually light the pilot.

TO LIGHT PILOT AND MAIN BURNERS:

1.Turn off electric power to unit.

2.Turn room thermostat to lowest setting.

3.Turn gas valve knob to on position.

4.Turn on electric power to unit.

Unitary Products 21