Airflow and temperature rise check

What is going on

At startup on this Trane, confirm airflow by checking inlet and outlet air temperatures against the furnace rating plate. Do it with the furnace stabilized and the panels in place, because open panels give false readings. Never change a motor speed without first disconnecting power.

Likely causes

• Temperature rise outside the nameplate range because of blower speed
• Dirty filter or restricted ductwork reducing airflow
• Readings taken before the furnace stabilized

Check in this order

1. Run the furnace until temperatures stabilize with all panels closed.
2. Check inlet and outlet air temperatures against the ranges on the furnace rating nameplate.
3. If airflow must change, turn off power and use the wiring diagram to change the blower motor speed.
4. Recheck the temperature rise after the change.
5. Check the filter and registers if the rise stays out of range.

More furnace guides

• Abnormal conditions and protection
• Adjust gas valve manifold pressure
• Air for combustion and ventilation in non-direct vent installs
• Airflow adjustment check
• Bottom return filter rack installation (upflow)
• Carbon monoxide detectors and signage for Massachusetts side-wall venting