035-17233-000-C-0702

3.A Low Pressure Switch/Loss Of Charge to protect against loss of refrigerant charge. (Opens at 7 psig + 3 and resets at 22 psig + 5)

If either one of the above safety controls opens, that individ- ual refrigerant system will be locked out. The other refrigerant system will continue in operation unless it too is effected by the same fault. The lock out of either system can be reset by opening the 24V circuit either at the room thermostat or at the unit disconnect.

HEATING SYSTEM

The following sequence describes the operation of the gas heat section.

CONTINUOUS BLOWER

With the room thermostat switch set to ON, the supply air blower will operate continuously. The normally closed contact K5-1 provides 24 volt power to the M3 contactor. The M3-1, 2 & 3 power contacts close and the blower motor operates.

INTERMITTENT BLOWER

With the room thermostat system switch set to the AUTO or HEAT position and the fan switch set to AUTO, the supply air blower will operate after the room thermostat calls for heat and the time delay relay closes.

The TH1 closes, the heat relay RW1 is energized. The RW1- 1 power contact closes energizing the line voltage draft motor. The RW1-2 contact is also closed. As the speed of the draft motor reaches approximately 2500 RPM, the centrifugal switch contact located on the end of the draft motor shaft closes to power the first stage ignition module IC1.

REDUNDANT

 

MAIN VALVE

VALVE

 

 

GAS MAIN

 

GAS

 

TO MAIN

VALVE

TO PILOT BURNER

BURNER

 

 

FIGURE 14 : GAS VALVE PIPING

Ignition module IC1 will immediately start the first stage igni- tor sparking and will open the redundant valve located inside the first stage main gas valve GV1 to allow a flow of gas to only the first stage carryover tube. See Figure 14. Only after the pilot flame has been ignited and the presence of pilot flame detected at the IC1 by a signal sent back through the flame sensor is sparking terminated and the first stage main gas valve opened.

Gas flows into each of the main burners and is ignited from the carryover tube flame.

If IC1 fails to detect a pilot flame, it will continue to try for a maximum of 85 seconds to ignite the pilot tube. If the pilot flame is not detected, then IC1 will lock out first stage furnace operation until 24V power is removed from the module either at the unit or by resetting the room thermostat.

At the same time power was supplied to the RW1, a parallel circuit activates ETD which closes the ETD contact after approximately 35 seconds and energizes K5 which closes K5-2 and starts the blower by energizing M3.

When TH2 closes, heat relay RW2 is energized. The RW2-1 contact is closed energizing the second stage ignition module IC2. IC2 will immediately start the second stage ignitor spark- ing and will open the redundant valve located inside the sec- ond stage main gas valve GV2 to allow a flow of gas to the second stage carryover tube. See Figure 11. Only after the pilot flame has been ignited and the presence of pilot flame detected at IC2 by a signal sent back through the flame sen- sor is sparking terminated and the main gas valve opened.

Gas flows into each of the second stage main burners and is ignited from the carryover tube flame.

If IC2 fails to detect a pilot flame, it will continue to try for a maximum of 85 seconds to ignite the pilot tube. If the pilot flame is not detected, then IC2 will lock out first stage furnace operation until 24V power is removed from the module either at the unit or by resetting the room thermostat. Note that the second stage furnace can operate even if first stage has locked out.

When the heating cycle is complete, TH2 opens de-energiz- ing the RW2 then TH1 opens de-energizing RW1 and ETD, thus closing all gas valves. The blower motor will continue to run (approximately 45 seconds after the furnace is shut down) until ETD opens, de-energizing the K5 relay and M3 contactor.

SAFETY CONTROLS

The control circuit includes the following safety controls:

1.Limit Control (LS). This control is located inside the heat exchanger compartment and is set to open at the tem- perature indicated in Table 16. It resets automatically. The limit switch operates when a high temperature con- dition, caused by inadequate supply air flow occurs, thus shutting down the ignition control and closing the main gas valves and energizing the blower.

2.Centrifugal Switch (CS). If the draft motor should fail, the centrifugal switch attached to the shaft of the motor pre- vents the ignition controls and gas valves from being energized.

20

Unitary Products

Page 19 Page 21
Page 20
Image 20
Energy Tech Laboratories DHG240, DHG180 installation instructions Heating System, Intermittent Blower
Page 19 Page 21

DHG180, DHG240 specifications

Energy Tech Laboratories has made significant strides in the realm of energy efficiency and renewable technologies with the introduction of their innovative models, the DHG240 and DHG180. These advanced devices are designed to optimize energy consumption, minimize environmental impact, and enhance overall energy management.

The DHG240 model stands out with its high-capacity performance, delivering a robust output of 240 kW. This unit is ideal for large facilities and industrial applications, where energy demands are high. One of its main features is its advanced algorithm for energy distribution, which allows for optimal load balancing across various operational units. This ensures that energy is used efficiently, reducing waste and lowering operational costs.

Similarly, the DHG180 is designed for medium-sized operations, providing an output of 180 kW. It offers an effective solution for businesses seeking to improve energy efficiency without the excessive overhead costs typically associated with larger systems. The DHG180 incorporates state-of-the-art monitoring systems that provide real-time data on energy consumption, allowing operators to make informed decisions and adjust settings as needed.

Both models integrate cutting-edge technologies such as smart grid capabilities and renewable energy sources. They are equipped to handle integration with solar panels and wind turbines, enabling facilities to harness clean energy and reduce reliance on fossil fuels. This feature not only contributes to sustainability goals but also provides a buffer against fluctuating energy prices.

The design of both the DHG240 and DHG180 prioritizes durability and reliability. They are constructed from high-quality materials that withstand harsh operational conditions, ensuring a long lifespan and reduced maintenance costs. Furthermore, these systems are compliant with various energy efficiency standards, making them a responsible choice for environmentally conscious businesses.

User-friendliness is another hallmark of these devices. An intuitive interface allows operators to easily monitor and control energy usage, while remote access compatibility enables management from off-site locations. This flexibility is crucial in today’s fast-paced business environment.

In conclusion, Energy Tech Laboratories’ DHG240 and DHG180 models represent the forefront of energy technology. By delivering high performance, integrating renewable solutions, and prioritizing ease of use, these units empower businesses to achieve their energy efficiency goals while promoting sustainability. Whether for large industries or medium-sized enterprises, these systems are engineered to meet the dynamic needs of modern energy management.
Top Page Image Contents