Troubleshooting Guide: 422 Universal Reset Module

Screen Is Blank

• The 422 gets power from the 24VAC plug on the back. Check that the zone/power manager beside the 422 is getting power.
• If the zone/power manager is receiving voltage, use a meter to check that the plug has 24VAC. To do this, you may have to strip a piece of thermostat wire and insert it into the pins so your meter probes can connect. Be careful not to touch wires together to short out the 24VAC. If the zone/power manager is not sending the voltage, replace the zone/power manager.

Check Sensors

• Start by going through the View menu and ask the question: "Am I getting accurate numbers back?"
• If you're in the middle of a New England blizzard and the outdoor sensor says it's 90°F outside, is this reasonable?
• If you see bad numbers, it's time to grab an ohm meter and start measuring. Refer to the sensor manual or 'Sensor Troubleshooting Guide' and follow testing instructions.

Other Sensor Issues

• Another source of sensor error is placement or wiring to wrong terminals. Examples include mixing supply sensors wired to the Boiler supply terminals, outdoor sensors placed in the sun, or right beside boiler exhaust vents. Sensors must be placed where they get accurate temperatures for the designated input to the 422.

Outdoor Sensor Notes

• The 422 requires an outdoor sensor so that outdoor reset can do the math properly and follow WWSD for the heating calls.
• DHW and setpoint calls are not affected by WWSD.
• If you need to bypass WWSD to get heat, see notes below on bypassing the outdoor sensor.
• In cases where it's not practical to use a wired outdoor sensor, consider the 087 wireless outdoor sensor.

Bypassing Outdoor Sensor

• Common reasons for bypassing the outdoor sensor include turning on the heat in the summer to test equipment, or the outdoor sensor is reading high and putting the unit in WWSD in the winter.
• You can check the current outdoor sensor reading and adjust the WWSD above it. Make sure you write down what the setting was before you change it so it can be reset when done.
• Another way to bypass the sensor is to remove the wire from the Out sensor terminal (70). The 422 will give you an 'Outdoor Open' error, but the 422 will operate as if it's 32°F (0°C) outside. If you can't get to a supplier for a new outdoor sensor that day, doing this will let the 422 supply heat until you can source one and come back.

Boiler Not Firing

• In the View menu, what is the Boiler Target vs Boiler Supply? If the boiler is at the target, why fire?
• What is the differential? The 422 fires the boiler until it reaches the boiler target, plus half of the differential. Then it waits until it reaches half the differential below the target before firing the boiler again. Is the boiler in the cool down cycle?
• Is there a call for heat showing in the View menu?
• Is the On-Off/Mod DIP switch in the correct position for the type of boiler?
• Does the 422 View screen show the burner symbol?
• Check the output of the 422. Is it sending out the correct signal to the boiler? If this is the case, look at field wiring or the boiler itself.

Not Turning on the Mixing

• Is unit in WWSD?
• In the View menu, what is the Mix Target vs Mix Supply? Why dial up the mixing if it's at target?
• Is the control for the mixing device 440/444 configured properly? The mixing devices can perform mixing with either a floating action valve or an injection pump.
• If using a floating action valve, are the open and close contacts reversed?
• What type of pump is being used to perform the mixing operation? The 422 requires a standard wet rotor non-ECM pump.

Checking a Floating Action Valve

• Are the open and close contacts reversed?
• When going through the test procedure (via the Test button), it will open and close the valve. When opening the valve, you should see 24VAC between C and Opn and 0VAC between C and Cls. It will be the opposite when closing.
• To isolate the output of the mixing device, label and remove the wires that go to the actuator. Re-run the test procedure and check voltages. If the device is putting out the proper signal, then you need to check field wiring or the actuator.
• To test the actuator, label the wires, remove them, and apply 24VAC directly to the open or close. It's also possible the valve assembly may be sticky. To test for this, remove the actuator from the valve and re-run the test to see if the actuator moves freely.

Checking a Variable Speed Pump

• The 422 operates a standard wet rotor non-ECM pump as a variable speed pump. It does this by controlling the voltage's sine wave that goes out to the pump. It is normal to measure the full 120Vac while operating below 100% mixing output, even at 0% output.
• Is the mixing pump the correct type? It requires a standard wet rotor non-ECM pump.
• When running the test, do you feel or hear the pump ramping up and down?
• Another way to test the pump itself is to wire it straight to 120VAC, and it should run at full speed.

Notes on Bus Configuration

• The 422 can have up to 2 mix temperature buses. Mix 1 zones & connections come through the zone/power manager that is paired beside the 422.
• The second bus comes in on terminals 59&60. These can be assigned to either be a boiler bus or Mix 2. This is set by the Boiler/Mix 2 DIP switch on the left of the 422.

DHW

• DHW calls are not affected by WWSD.
• The DHW call comes from an aquastat that must provide a voltage ranging from 20-260VAC across DHW Demand (terminals 53&54).
• Is the DHW mode setting correct? Check the DHW pump piping against the DHW mode diagrams on page 24 of the Data Brochure (I/O manual). Pick the correct mode so the system pump runs if necessary.
• If the 422 is in Away mode, DHW calls will be ignored.

Notes

• To see all available settings, go into the Misc menu and set access level to Ad (Advanced).
• On the 422, not all menu settings in the manual appear. Some will be invisible based on bus configuration.

Sensor Resistance vs Temperature

Call customer service if you need assistance with technical details.

All specifications are subject to change without notice.

Tel: 1-800-438-3903 Fax: (250) 984-0815

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