Arrived onsite for no heat call. System was switched off upon arrival. Turned system on and system fired up. Then failed after 2 minutes. No error codes. Reset the system, placed probes on the system. The system restarted and didn’t fail again. Measure 56 degree temperature rise which is in range but high. Observed a bit of a dancing flame. Inspected flame safety system and did not observe issue. Duct work is not correct. There is no return box and no supply plenum. Most likely the system is struggling to overcome issue with the ductwork. Next step is to perform a heating maintenance with combustion analyzer. Then see about pricing out a ductwork repair.
