feeling chilly due to malfunctioning furnace

Winter is here. You can already start feeling the cold breeze blowing and the heat subsiding. The temperature will soon drop to uncomfortable levels. Ensure that both you and your family are spared from freezing nights.

Check your furnace early on to see whether it is working as it should. Some issues can be quickly fixed while others aren’t so simple. For instance, short-cycling is one key issue that requires professional attention. A furnace short cycles if the furnace runs then shuts off and starts again repeatedly.

How Can I Tell If My Furnace Is Short Cycling?

A properly functioning furnace turns on and runs continuously until the desired temperature is achieved. It will then turn off thus allowing the space to maintain that temperature level. It will be a while before it turns on once more due to the dropping temperatures.

A short-cycling furnace, on the other hand, will turn on and off again in quick succession. It won’t reach the thermostat setting. It will simply shut down and run again thus causing wear and tear on the system. The house will feel cold throughout the day even though the furnace is running.

Why Do Furnaces Short Cycle?

image of why furnace short cycles

The situation cannot persist. It is a waste of energy and causes damage to components while allowing the house to become cold. If this problem is noted, it should be quickly addressed. The proper solution depends on the actual cause. Here are some things that are likely to trigger such erratic behavior:

1. Overheating Furnace

HVAC systems come with built-in protection from damage. While a furnace is designed to heat up the house, it is possible for the unit to get too hot. It can detect when it crosses a dangerous level and turns itself off immediately.

The furnace takes this emergency measure as a way to prevent damage such as cracks from developing in the heat exchanger. Carbon monoxide, which is lethal, may leak from such cracks and you need to be grateful it stopped when it did.

Overheating is usually the result of airflow restrictions caused by dirty air filters or blocked exhaust vents.

2. Faulty Flame Sensor

image of a gas furnace

If the flame sensor in your furnace is faulty, you can expect the flame to shut down immediately after it lights. It is important to understand that the sensor’s purpose is monitoring the gas valve. It is a safety measure aimed at preventing raw gas from getting into the home. If there’s no flame it shuts down.

If the flame sensors are malfunctioning, they will shut off the gas valve even when it is necessary. You can try fixing the problem by calling an HVAC contractor to clean the sensor. If that fails to work, then they may suggest a replacement. Once again, you need to find an HVAC technician to do it for you.

3. Dirty Furnace Filter

replacing furnace filter

Short-cycling can also be caused by a dirty furnace filter. Unlike a faulty flame sensor that triggers an immediate shut-off, a dirty filter will let the furnace run for several minutes before it shuts down. You may also notice that heat grates pump out hotter air than what you might be used to.

If the furnace filter gets dirty, the air is unable to flow back to the furnace and cool it down. The heat will just build up to unmanageable levels. It will then shut down automatically as a safety precaution. If you have a washable furnace filter, clean it. However, if it is disposable, you should replace it.

4. Blocked Heat Grates

The furnace heats up the air and pushes it out to the grates. If the hot hair is unable to freely flow out of these heat grates, heat will be trapped inside thus causing the system to overheat. You will then have another short-cycling episode unless the underlying issue has been resolved.

Keep in mind that grates have control mechanisms known as dampers that allow occupants to control whether a room gets heated or not. It is a useful feature to have for energy savings. A high number of closed vents, however, may lead to overheating. Always try keeping 75 percent or more of these always open.

5. Blocked Exhaust Vent

The exhaust vent must always stay open. However, sometimes the vents do get blocked due to nests, snow, vegetation, beehives, and so on. It is important to remove all obstructions without delay. In fact, it is one thing that needs to be regularly checked as part of HVAC maintenance.

It can sometimes be tricky such as when a dangerous animal is the one blocking the openings. If that’s the case, you should call animal control as opposed to exposing yourself to harm.

6. Wrongly Placed Thermostat

thermostat and comfort control

The thermostat has sensors used to gauge indoor temperature. It regulates the activity of the furnace in response to what it senses in the environment. It might thus not do its job right if it is not placed in the right spot.

For instance, if it is placed near a heating grate, a sunny window, or any other hot spot, it will definitely have skewed sensor readings. The thermostat will think that the house is heated enough thus triggering a premature shutdown.

Install the thermostat in a neutral location, away from anything that may grossly influence the temperature readings.

7. Your Furnace Is Too Large

It might be tempting to get a large furnace when looking to feel secure about the heating system’s capabilities. Bigger, however, is not always better. Excess capacity, when it comes to furnaces, can be detrimental because it triggers short-cycling.

The components will wear down quicker, temperature swings become more pronounced, and the heating bills will be higher than usual. Replacing the unit with a furnace of the right size is the sensible yet costly solution. Fortunately, an experienced HVAC contractor can perform very precise calculations for the furnace size to meet your heating needs.


Fix your furnace issues early to make your home comfortable this winter. If you notice the furnace short-cycling, determine the cause based on the clues provided. Get help from an expert HVAC technician for proper diagnosis and repairs. Your diligence will translate to a stress-free winter as well as a longer-lasting heating system.

Contact Tower Energy For All HVAC Requirements

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If you are looking for superior heating and cooling services throughout Hartford County, Connecticut, you should always count on Tower Energy. We have a team of the best HVAC technicians who are both certified and experienced to provide you with the best HVAC installations, repairs, replacements, and tune-ups. All our technicians have the experience and knowledge needed to correctly service your HVAC system.

Tower Energy guarantees the most competitively priced heating and cooling services in the area. Our maintenance services can increase your energy efficiency, improve your comfort, and reduce your home cooling costs.

If you need HVAC system replacement or repair, we can recommend the best one for your home without going over the budget. All our work is backed with a guarantee to ensure maximum satisfaction. Contact Tower Energy today to schedule your service appointment. We offer free, in-home estimates.

Contact us now or call us at (860) 677-7347 to find out more.