What Can Cause a Furnace to Short Cycle?

H2C Heating Cooling & Plumbing > Blog > What Can Cause a Furnace to Short Cycle?

What Can Cause a Furnace to Short Cycle?

Short cycling occurs when a furnace rapidly turns on and off for short periods of time (usually four to seven seconds per cycle). This is an annoying problem. When a furnace short cycles it uses more energy than usual. Furnace short cycling can even damage your unit.

Here are some common reasons why furnaces short cycle.

Thermostat Issues

If your thermostat is placed near a heat source, it will warm up quickly and signal your furnace to shut down before the entire home is adequately warmed. Do not place your thermostat over a heat register or near a drafty window or door.

Check your thermostat’s wires to see if they are frayed. Check for loose connections and disconnected wires. If the circuit breaker has tripped, reset it. Thoroughly clean thermostat components. Make sure your thermostat is set to heat. If the problem persists, reach out to a furnace repair pro in Minneapolis for help.

Clogged Air filters

Over time filters become clogged with contaminants such as pollen, dander and dust. A dirty filter can cause airflow issues and a pressure backup. The warm air in the furnace raises its internal temperature, causing it to shut down.

To prevent performance issues, replace furnace filters every 30-90 days. Refer to your owner’s manual to determine the right type and size. If you have any doubts or questions, do not hesitate to call up your contractor.

Blocked Heat Register

Closed or blocked registers or dampers on the forced air ducts can cause the furnace to overheat and shut down repeatedly. Check your duct registers to make sure they are unobstructed. If a piece of furniture is blocking a register, relocate it.

Oversized Furnace

An oversized furnace will heat your home quickly, but unevenly. Your furnace will turn on and off too frequently to maintain consistent temperature throughout your house.

Bad Limit Switch

The limit switch turns the burners on and off. A faulty limit switch can cause your furnace to shut down prematurely. The system will short cycle in an attempt to meet the thermostat’s demands.

Replacing a limit switch may involve installing or connecting wires. If you haven’t replaced a limit switch before, get help from an expert.

Malfunctioning Flame Sensor

The flame sensor is an important safety component on furnaces. It detects and confirms if a flame is burning. If no flame is detected, the sensor shuts off the furnace to prevent a gas leak.

Over time, dust builds up on the flame sensor. A dirty or damaged flame sensor can malfunction causing your furnace to short cycle. Check your flame sensor regularly and clean or replace them as necessary.

Have a furnace installation project in Minneapolis? H2C Heating Cooling & Plumbing will manage it from start to finish. Our proven track record of delivering projects on time and on budget gives us a competitive edge. To consult one of our pros, call 651-368-6245.