Page 6: Adjustment Of Fan Control Settings YUM-A The inducer is energized and ramps up its speed until airflow is proven by the pressure switch and by the pressure sensor on the control board.
The hot surface ignitor is energized. After a second igniter heatup, the gas valve opens and the burners light. There may be a potential shock hazard from the components of the hot surface ignition system.
The furnace can only be lit automatically by its hot surface ignition system. Page Limited Warranty Subject to change without notice. Printed in U. All rights reserved.
Print page 1 Print document 12 pages. Rename the bookmark. Delete bookmark? Cancel Delete. Delete from my manuals? Sign In OR. Don't have an account? Sign up! Restore password. Upload manual. Upload from disk. Examine the furnace casing for obvious signs of deterioration. Examine the burner flames to make sure they are in good adjustment.
Refer to the pictorial sketch shown in Figure 2 as a comparison to the actual flame. Examine the furnace as outlined above in steps 1 - 6 before each heating season. Use Figure 3 for visual reference. Store cleaning materials near your furnace. Materials such as bleaches, detergents, powdered cleansers, etc. Use the area around your furnace as a storage area for items which could block the normal flow of air.
This flow of air is required for ventilation of the various furnace components. Your furnace is a very easy appliance to take for granted.
Season after season, it sits there in your home, keeping you warm and comfortable. For this reason, you may never have given much thought to the way your furnace operates. In order to get the safest and most efficient operation from your furnace, you should understand how your furnace does its job. When you set your thermostat to provide more heat in your home, you are starting the heating cycle of the furnace.
First, the inducer motor starts to purge the heat exchanger of any remaining gases. Next, the hot surface ignitor glows and after a warm-up period the gas valve opens and ignition occurs. A short time later, the blower starts and distributes the warm air throughout the home.
The furnace control will vary the amount of heat and the amount of airflow needed to maintain the proper temperature in the home. This appliance does not have a pilot. It is equipped with an ignition device which automatically lights the burner. Do not try to light the burner by hand. Be sure to smell next to the floor because some gas is heavier than air and will settle on the floor.
Never use tools. Force or attempted repair may result in a fire or explosion. Do not use this appliance if any part has been under water.
Immediately call a qualified service technician to inspect the appliance and to replace any part of the control system and any gas control, which has been under water. Read the safety information above. Set the thermostat to the lowest setting. Turn off all electric power to the appliance. Do not force. Wait five 5 minutes to clear out any gas. If you then smell gas, STOP! Turn on all electric power to the appliance. Set thermostat to the desired setting.
Burner will light, which may take seconds. Set the thermostat to lowest setting. Turn off all electric power to the appliance if service is to be performed. Replace burner access panel.
Refer to Figure 5. NOTE: The spring-loaded safety cut-off switch, mounted on the blower deck, behind the indoor fan access panel will automatically cut off the electrical power supply to the furnace when the blower panel is removed.
As a safety precaution, all electrical power and the gas supply to the furnace should be turned off before servicing. Before proceeding, be sure the area is well ventilated. Turn the thermostat OFF. If the blower is running, wait until it stops automatically. Remove the vent blower housing blower and the condensate pan. Using a stiff wire brush, remove the loose scale or soot from each tube.
The vent terminal. Vacuum the secondary heat exchanger. The furnace vent and combustion air intake passageways. Finish the cleaning procedure by following steps 9 - 11 under cleaning the Heat Exchanger. The furnace burners, ignitor and flame sensor. The condensate collection and disposal system. If any disassembly of components containing flue or vent gases is required, a qualified service agency must perform the service.
If cleaning is required, follow this procedure: 1. Turn off the electrical power to the unit. Turn off the gas supply at the external manual shut-off valve and loosen the ground union joint. When the wall thermostat R and W contacts close, indicating a call for heat, the following sequence occurs: 1. Remove the burner door and remove the burner box cover. Disconnect wires from flame sensor, rollout switch and HSI igniter.
Remove igniter carefully, as it is easily broken. Remove the screws that hold the burner box assembly to the vest panel and remove the assembly. Remove burners from the burner assembly. Burners may be cleaned by rinsing in hot water. Reassemble the burners in the reverse order. Cleaning the Heat Exchanger 1. Unitary Products Group The inducer is energized and ramps up its speed until airflow is proven by the pressure switch and by the pressure sensor on the control board.
The hot surface ignitor is energized. After a second igniter heatup, the gas valve opens and the burners light. When the control senses that flame is present, the circulating blower starts at low speed. When the thermostat R and W contacts open thermostat is satisfied the furnace control recalculates the demand and a new firing rate. If demand exceeds the minimum firing rate, the burners will continue to fire at a recalculated reduced firing rate, decreasing if the thermostat remains off for a defined time.
If demand does not exceed the minimum firing rate, the burners will shut off immediately. After the burners shut off, the circulating blower will continue to run until the temperature sensor detects that the supply air temperature has dropped to the desired level, which should take from 30 to 90 seconds. The COOL jumper has four positions, which will deliver sufficient airflow in cooling mode for the cooling capacities shown in Table 2. The ADJ jumper has three positions which can be used to make further adjustments to the cooling blower airflow.
See Table? The jumper has three positions. This profile is best-suited for installations where the humidity is frequently very high during cooling season, such as in the southern part of the country.
In every case, it will take the motor 30 seconds to ramp from one speed to another. Tap C is the dry profile. This profile is best suited to parts of the country where excessive humidity is not generally a problem, where the summer months are usually dry.
On a call for cooling the motor will ramp up to full capacity and will stay there until the thermostat is satisfied. Then it will ramp down to zero. Tap D is the normal profile, best suited for most of the country, where neither excessive humidity nor extremely dry conditions are the norm. There may be a potential shock hazard from the components of the hot surface ignition system. The furnace can only be lit automatically by its hot surface ignition system.
Check to see that the power to the furnace and the ignition control module is ON. The manual shut-off valves in the gas line to the furnace must be open. Make sure all wiring connections are secure. Review the sequence of operation. Start the system by setting the thermostat above the room temperature. These can be chosen so as to maximize the comfort and sound levels for various regions of the country.
Tap A is the default profile. It provides a second ramp-up from zero airflow to full capacity and a second ramp-down from full capacity back to zero airflow. Whenever there is a change in airflow mode, such as from low heat to high heat, the motor will take 30 seconds to ramp from one speed to the other.
To do so will allow furnace to operate under potentially hazardous conditions. Do not try to repair controls. Never adjust pressure switch to allow furnace operation. If a system problem occurs, a flashing LED shows a fault code. The LED can flash red, green or amber to indicate various conditions.
The LED is located on the furnace control board and can be seen through the clear view port in the lower door of the furnace. The pattern will be repeated the number of times equal to the flash code. For instance, a "six flash code" will be indicated by the LED turning on and off six times.
There will be a two second off period between each set of flashes. Check the 24 volt control circuit fuse on the board. Check the circuit breaker or fuse on the volt supply power to the furnace. Check that the 24 volt transformer. One Green Flash - Normal Operation with no call for heat. Two Green Flashes - Indicator for "No error codes in memory".
Three Green Flashes - Indicator for "Error codes cleared from memory". This mode is used only during factory run-testing of the furnace. To stop this mode, cycle power to the furnace off and then back on. One Amber Flash - Normal operation with call for cooling. Two Amber Flashes - Normal operation with call for heat. Three Amber Flashes - Normal operation, burner is on at end of heating cycle after wall thermostat has been satisfied.
Four Amber Flashes - Heating capacity is reduced due to restriction in the circulating air system. Check for dirty filter or closed registers. Five Amber Flashes - Heating capacity is reduced due to restriction in the combustion air or vent system. Above 4, feet altitude, this may also indicate automatic, normal derating for altitude. Rapid Amber Flash - Low flame sense current.
Check for dirty or mislocated flame sensor rod. One Red Flash - Flame is present with no power being supplied to gas valve. This can be caused by a gas valve that is slow to close or that leaks gas through to the burners. Two Red Flashes - Stuck closed pressure switch. The control confirms that the pressure switch contacts are open at the beginning of each cycle. This could be caused by a faulty pressure switch or by mis-wiring of the pressure switch. Three Red Flashes - Stuck open pressure switch.
This indicates that the pressure switch is open when it should be closed. This could be caused by a faulty combustion air blower, blocked vent pipe, blocked air intake pipe, blocked condensate drain, faulty pressure switch hose or a faulty pressure switch. Four Red Flashes - High limit switch open or 24 volt fuse is open.
This may be caused by a dirty air filter, improperly sized duct system, faulty blower motor, restricted circulating airflow or an open fuse on the control board. Check the limit switch mounted in the combustion air blower housing. Six Red Flashes - Current failure on modulating gas valve. Seven Red Flashes - Lockout due to no ignition.
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