Bosch Insufficient Heat Output

Furnace produces heat but house never reaches set temperature; runs for long periods

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

Incorrect gas pressure or orifice size, Partially blocked heat exchanger, Circulation pump on wrong speed, Thermostat miscalibrated or poorly located

Safety: Do not adjust gas components yourself.

Thermostat location: Ensure the thermostat is not near drafts, direct sunlight, or heat sources. Relocate if necessary.
System balancing: Open all supply registers or radiators fully and ensure return paths are not blocked.
Pump speed: On Bosch hydronic systems with multi-speed pumps, verify the pump is set to the recommended speed (usually medium or as per manual).

Gas input and combustion checks must be done by a licensed technician with proper instruments.

Medium 3/5

Circulation Pump

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