tekmar 421 Mixing Reset Module - Manual (Page 19)

19 of 20 © 2007 D 421 - 08/07
Troubleshooting
Symptom Possible Causes Corrective Action
Boiler does not fire when there
is a mix demand. Boiler contact is not connected to boiler
thermostat connection.
Trace wires from boiler contact to boiler
thermostat connection. Use the Test
sequence to check the boiler contact.
Mixing valve will not open.
No voltage present on actuator motor. Mix 1 Mode setting must be set to FLt.
Boiler Return Protection.
Mixing valve will not open until the boiler
supply temperature exceeds the boiler
minimum setting.
Actuator rotating in wrong direction to open
valve. Reverse open and close wires on
actuator.
Variable speed injection pump
does not operate.
No current present on variable speed
injection pump.
Mix 1 Mode setting must be set to VAr.
Boiler Return Protection.
Variable speed injection pump will not
operate until the boiler supply temperature
exceeds the boiler minimum setting.
A non-wet rotor pump has been installed.
Variable speed injection will only operate
with wet rotor pumps. Read E021 and check
pump type.
Fuse is blown.
Determine if pump is jammed or seized.
Replace fuse.
Display is not on.
No voltage to control.
Check breaker panel or disconnect. Check
voltage using a voltmeter.
Plugs are not connected between the 421
to the Zone Manager. Ensure the plugs are secured to the Zone
Manager pins.
Fuse is blown.
Check fuse on Zone Manager. Check
total VA draw on all thermostats and zone
valves connected to the Zone Manager.
This cannot exceed 40 VA.