Boiler runs but does not heat the house adequately; radiators or baseboards are lukewarm.

Safety first: Surfaces may be hot. Turn off power before adjusting wiring or pumps.

• Check boiler temperature: On the Laars display, note the supply temperature during a call for heat. If it is much lower than design, the setpoint or reset curve may be too low.
• Adjust thermostat and reset curve: Temporarily raise the thermostat and, if you have access, increase the boiler setpoint or outdoor reset curve slightly following the manual.
• Bleed air: Air in radiators or loops can reduce heat. Bleed radiators and check for air at high points.
• Verify all zones are circulating: Ensure all zone valves open and all circulators run when their thermostats call.

When to call a professional: If the boiler cannot reach set temperature or the system remains underheated, a technician should evaluate sizing, flow, and control settings.