Receive a no heat complaint from a grocery store in Apple Valley, California. Our commercial technician found RTUs #9, 10 and 11 in alarm. #9 would not reset, will need to return in the AM to determine the burner control alarm. #11 burner control had no power, will need to trace for short in wiring. Moved to unit #10 and found the linkage for the gas valve had come undone. Repaired and tested, #10 back online. Will return tomorrow AM to continue troubleshooting #9 and #11.