NTI Insufficient Heat Output

Boiler runs but house does not reach set temperature; heat output seems low

Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Outdoor reset curve set too low, Partially blocked heat exchanger, Low gas pressure, Air in system reducing flow

How to Fix / Troubleshooting

Safety: Do not adjust gas components without proper instruments and licensing.

Check control settings: Review NTI control parameters for maximum supply temperature and outdoor reset curve. Increase within safe limits if set too low.
Bleed air: Remove air from radiators and loops to restore full flow.
Filter/strainer: Clean any system strainers to improve circulation.
Professional gas check: Have a technician verify gas supply pressure and clean the heat exchanger if combustion efficiency is low.

Repair Difficulty

Medium 3/5