Product Overview

60
103859-12 - 8/19
MPO-IQ
Installation & Service Manual
F. USE BOILER CONTROL DISPLAY STA (STATUS) NUMBER TO GUIDE TROUBLESHOOTING
The Boiler Control will flash “STA” followed by a number. Use this number to identify the boiler problem in the
table below:
1. Burner and Circulator Off
Display / Status Recommended Corrective Action
STA1
Standby
Burner off
Circulator off
The boiler has not detected a call for heat (hr = off and dh = off).
Ensure there is power to the boiler control.
Check the thermostat:
- When a thermostat call for heat is detected boiler control display “hr” will show “on”
- Make sure thermostat is calling for heat and contacts (including appropriate zone controls)
are closed. Check for loose connection.
Check the DHW demand:
- When a domestic call for heat is detected boiler control display “dh” will show “on”
- Make sure the DHW aquastat contact is closed. Check for loose connection.
4. Circulator is On, But Oil Primary is in Standby
Display / Status Recommended Corrective Action
STA15
Limit Open
Heat Request occurs and start of operating sequence is halted due to an open limit. Open limits may include
Auxiliary High Limit or Low Water Cut-off Cards (when installed). If Boiler Control shows "StA 15" proceed to
Paragraph F.
3. Burner is On, But Circulator is Off
Display / Status Recommended Corrective Action
StA 8
Burner on
Circulator off
Domestic Hot Water (DHW) Priority Forcing Circulator Off
- When there is a DHW heat request wired to the boiler control’s ZR terminal the System Circulator will be
“forced off” for the duration of the DHW heat request. When the DHW heat request ends the System
Circulator “force off” is removed, the circulator can respond normally. When the Priority Time, (PT_)
Parameter is set to “off” the System Circulator is not “forced off” for a DHW call for heat.
- When there is DHW heat request and an Outdoor Air Reset IQ Card is installed the System Circulator will be
forced off for the duration of the Reset Card’s Priority Time (PT_) parameter. Check Priority Time (PT_)
parameter using the Outdoor Air Reset IQ Option Card Adjustment Mode (see Reset Card Adjustment Mode
Instructions).
Wiring / Circulator Issue:
- Check wiring for loose connection, miswiring
- Check circulator
Display / Status Recommended Corrective Action
STA1
Circulator
Pre-purge
Burner off
Circulator on
The boiler is warm and circulator is providing residual boiler heat to building:
Check boiler temperature
- The boiler will not start until boiler water temperature is less than the Setpoint (SP) minus differential (df)
- If boiler water temperature is higher than Start Temperature (ST_, default = 140 F) and the Circulator Pre-purge
(PP_, default = 2 minutes) time has not expired, boiler start will be delayed until water temperature drops or time
expires. To permit the boiler to start sooner increase Start Temperature parameter. Refer to Operation Section
for additional information.
2. Circulator is On, But Burner is Off
12 Troubleshooting (continued)