279550-YIM-A-0207

Welded Gas Valve Relay Response.

If either or both Pilot and Main Gas valve outputs are sensed to be off for more than 1 seconds when commanded to be on the control board shuts off all outputs and enters a hard lockout

If the Pilot valve or Main valve output is sensed to be energized for more than 1 second when commanded to be off, the control de-energizes the induced draft motor (if flame is not present) to attempt to open the pressure switch to de-energize the gas valve. If the pilot or main gas valve is still sensed as energized after the inducer has been off for 5 seconds, the control re- energizes the inducer to attempt to vent the unburned gas. In either case, the control enters a hard lockout. If the pilot or main valve becomes Un-Welded the inducer will de-energize, but the control will remain in a hard lockout.

During a hard lockout, the control board LED will remain off and the control will not respond to any thermostat demands.

The only way to recover from a hard lockout is to remove and then reapply 24VAC power to the control board.

Safety Controls

The control circuit includes the following safety controls:

1.Limit Switch (LS) - This control is located inside the heat exchanger compartment and is set to open at the temperature indicated in the Temperature Controls Table of the unit wiring diagram. It resets automatically. The limit switch operates when a high temperature condition caused by inadequate supply air flow occurs, thus shutting down the ignition control and closing the main gas valve and energizing the blower.

2.Pressure Switch (PS) - If the draft motor should fail, the pressure switch prevents the ignition controls and gas valves from being energized.

3.Flame Sensor - The flame sensor and controls are located per Proper Flame Adjustment Figure 19. 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.

4.Rollout Switch (RS) - This switch is located in the burner vestibule. In the event of a sustained main burner flame rollout, it shuts off the ignition control and closes the main gas valve.

NOTE: The manual reset Rollout Switch (RS) must be reset before allowing furnace operation.

5.Auxiliary Limit Switch (ALS) - This control is located inside the heat exchanger compartment and is set to open at 160°F. It is a manual reset switch. If ALS trips, then the primary limit (LS) has not functioned correctly. Replace the primary limit LS.

Table 18: Ignition Control Board FLASH CODES

Flash Code

Description

On Steady

Control Failure - Replace Control

Heart Beat

Normal Operation

1 Flash

Not Applicable

2 Flashes

Pressure / Centrifugal Switch Open with Inducer On

3 Flashes

Pressure / Centrifugal Switch Closed with Inducer Off

4 Flashes

Not Applicable

5 Flashes

Lock Out From Too Many Flame Losses

6 Flashes

High Temperature Switch Open (Primary or Aux.)

7 Flashes

Rollout Switch Open

8 Flashes

Flame Present With Gas OFF

Cooling Sequence Of Operations

When the thermostat calls for first-stage cooling, the thermostat terminals G and Y1 energize, signaling the compressor, indoor blower and outdoor fan to operate. The indoor blower will operate according to the fan delay profile selected using Table 17.

When the thermostat calls for second-stage cooling the thermostat terminal Y2 energizes, signaling the compressor bypass ports to close and the indoor blower to increase speed. If the outdoor fan motor has an ECM controller, Y2 will also signal the motor to increase speed.

When the thermostat is satisfied, terminals G, Y1 and Y2 are de-energized, thus stopping operation of the compressor and outdoor fan. The indoor blower will remain on according to the fan delay profile selected using Table 17.

Safety Controls

The control circuit includes the following safety controls:

1.High Pressure Switch (HP)- This switch protects against excessive discharge pressures due to a blocked condenser coil or a condenser motor failure (opens at 625

± 25 psig and resets at 500 ± 25 psig).

2.Low Pressure Switch (LP)- This switch protects against loss of refrigerant charge (opens at 7 ± 3 psig and resets at 22 ± 5 psig).

The above pressure switches are specifically designed to operate with R-410A systems. R-22 pressure switches must not be used as replacements for the R-410A pressure switches.

The ability to properly perform maintenance on this equipment requires certain expertise, mechanical skills, tools and equipment. If you do not possess these, do not attempt to perform any maintenance other than those procedures recommended in this Installation Manual. Failure to heed this warning could result in serious injury and possible damage to this equipment.

24

Unitary Products Group

Page 24
Image 24
York R-410A dimensions Cooling Sequence Of Operations, Welded Gas Valve Relay Response, Safety Controls

R-410A specifications

York R-410A is a widely recognized and highly efficient refrigerant used in modern air conditioning systems. Developed as an environmentally friendly alternative to R-22, R-410A has gained popularity in the HVAC industry due to its numerous advantageous features and characteristics.

One of the main features of York R-410A is its ability to provide superior cooling performance. This refrigerant operates efficiently at both high and low temperatures, allowing systems using it to maintain optimal indoor climates even during extreme weather conditions. Its high energy efficiency ratio (EER) and seasonal energy efficiency ratio (SEER) ratings make it a preferred choice for energy-conscious consumers, resulting in lower energy bills and a reduced carbon footprint.

Technologically, York R-410A systems feature advanced compressor designs that enhance their overall reliability and performance. These compressors are often equipped with variable-speed technology, enabling them to adjust their output to match the cooling demands of the space. This not only improves comfort levels but also leads to efficient energy consumption, reducing wear and tear on the equipment over time.

Another significant characteristic of York R-410A is its non-ozone-depleting properties. Unlike its predecessor R-22, which is being phased out due to its damaging effects on the ozone layer, R-410A is designed to minimize environmental impact. Its lower global warming potential (GWP) further underscores its role in promoting sustainability within the HVAC sector.

Furthermore, York R-410A systems are engineered with enhanced safety features. The refrigerant is non-toxic and non-flammable, which makes it safer for use in both residential and commercial applications. Additionally, its high thermal stability reduces the risk of breakdown or leakage, contributing to longer system lifespans and lower maintenance costs.

In conclusion, York R-410A stands out as a cutting-edge refrigerant that combines efficiency, safety, and environmental responsibility. With its advanced technologies and remarkable characteristics, it meets the demands of modern air conditioning requirements while paving the way for a sustainable future in HVAC systems. Adopting York R-410A not only benefits individual users through improved comfort and lower energy bills but also plays a vital role in protecting our planet's ozone layer and mitigating climate change.