Pennco Short Cycling / Improper Control or Sizing

Boiler short cycles (turns on and off frequently) without satisfying thermostat

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

Oversized boiler, Incorrect aquastat or setpoint settings, Poor thermostat placement, Flow restriction causing rapid temperature rise

Safety first: Use caution around hot components.

Check thermostat: Ensure it is not located near a heat source or in direct sunlight. Relocate if necessary.
Review settings: Verify boiler high and low limit settings on the Pennco control match the installation manual and system design.
Inspect flow: Confirm all valves are open and circulator is properly sized and operating.
Consider buffering: In systems with very small zones, a buffer tank or control changes may be needed. Consult a heating professional.

Medium 3/5

High Limit Aquastat

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