Why Does My Furnace Keep Starting And Stopping? Vital Guide


  • Short-cycling furnaces are a common problem, characterized by frequent on-off cycling, energy waste, and component damage.
  • To address short cycling, it’s important to identify the root cause, which can include a faulty thermostat, dirty air filters, clogged ducts, or blocked heat registers.
  • Regularly cleaning and replacing air filters can help prevent short cycling and maintain proper airflow.
  • Uneven temperature distribution can contribute to short cycling, indicating restricted airflow or missing insulation in certain areas.
  • Resolving issues related to airflow restrictions and insulation can improve heating efficiency and reduce short cycling.
  • Short cycling can lead to furnace malfunctions and system breakdowns, as frequent starting and stopping can cause excessive pressure and damage the furnace over time.

So why settle for a long-lasting furnace when you can have a short-cycling one that keeps you on your toes?

Why Does My Furnace Keep Starting And Stopping

How Does Short Cycling Occur in Furnaces?

Short cycling is a common furnace issue. It happens when the furnace cuts off before completing a full heat cycle. Causes include a broken thermostat or a blocked air filter. This leads to less heat, energy waste, and stress on your furnace.

To avoid short cycling, keep your air filter clean and your thermostat in good shape. Schedule regular HVAC check-ups. Also, replace an old, hot motor.

In the 1800s, furnaces used coal and ran differently. Short cycling was not a problem since the heat was spread with gravity, not pumps. Now, technology has made our heating systems more efficient – but needing more care. So, why endure the rollercoaster of emotions? Install a short cycling furnace!

Common Causes of Short Cycling Furnace

Understanding the common causes of short cycling in furnaces is essential for maintaining efficient and reliable heating systems. This guide provides insights into the primary culprits behind frequent on-off cycling, helping homeowners and professionals diagnose and resolve the issues effectively. By addressing these causes, one can prevent energy waste and potential damage to furnace components. 

Dirty Air Filter

A dirty air filter is a common cause of short-cycling furnace issues. It traps dust & other particulates, clogging up airflow & causing the furnace to overheat & shut off prematurely. This reduces indoor air quality & increases energy bills.

Regularly replacing or cleaning the air filter is key, every 1-3 months depending on usage & environment. For pets & allergies, consider a HEPA filter. Professional maintenance will keep the furnace running at peak efficiency & prolong its life.

Set reminders for new filters & save money! It’ll improve comfort & health, too.

Malfunctioning Thermostat 

When your furnace is short cycling, it could be due to a malfunctioning thermostat.

  • The thermostat is responsible for detecting the temperature in your home and controlling the furnace.
  • If the thermostat is not functioning properly, it can send incorrect signals to the furnace, causing it to cycle on and off too quickly.
  • To troubleshoot temperature issues, check the thermostat’s batteries, wiring, and calibration settings.
  • Adjusting the heat anticipator setting on the thermostat may help regulate when the system shuts off.
  • If all attempts to fix the thermostat fail, it’s time to consider replacing it.
  • An HVAC technician can assist in selecting a suitable thermostat model for your home and professionally install it.

Issues with Blower Motor

The blower motor is essential for a working furnace. Problems can cause it to short cycle. Worn-out or blocked air filters can create heating issues.

If the blower motor isn’t functioning, it won’t push enough hot air through the vents. This causes the furnace to overheat and shut down for safety.

Regular maintenance checks are necessary to solve the problem. Clean/replace filters and lubricate motor components to prevent wear and tear. Upgrading to energy-efficient motors can reduce power use.

Professional help is best when dealing with furnace issues. They have more experience and the right tools. This ensures safe repair of the unit and a longer life for the HVAC system.

If the exhaust vent is clogged, call a pro before you’re left in the cold.

A clogged Exhaust Vent 

Your furnace is short-cycling – don’t worry, it’s just trying to get its cardio in with all that airflow restriction! This could be caused by a clogged exhaust vent, blocking airflow and leading to overheating. To fix this, follow these steps:

  1. Switch off your furnace.
  2. Locate the Exhaust Vent.
  3. Clean it thoroughly with a soft brush or vacuum cleaner.
  4. Remove any debris or obstruction that may have accumulated in the vent.
  5. Inspect the entire length of the vent for any damages.
  6. If necessary, call a professional technician to fix or replace the exhaust vent.

To avoid clogged exhaust vents, clean your furnace filters and vents regularly. Debris buildup reduces their efficiency, leading to inefficiency in the furnace’s performance. So, always clean your furnace filters at least once a month – even if they don’t appear dirty. Neglecting these small maintenance tasks could cause big issues later on.

Airflow Restriction

Check air filters often! Keep tabs on air ducts and vents too. These may be blocked, stopping air from flowing and affecting the furnace’s performance.

Restricted airflow is a hassle and can be dangerous. It can cause overheating and a fire hazard. Upgrade to a new, efficient furnace model with smart features for better monitoring.

Emergency calls due to heating system problems during winter are often caused by restricted airflow. Thus, it’s important to get a certified technician for regular maintenance checks. Keep your furnace running smoothly!

Low Gas Valve Pressure

Is your furnace short-cycling? This happens when it’s not getting enough fuel. Low gas valve pressure might be the cause. It could be due to a damaged or clogged gas line, or faulty valve that needs replacing.

Don’t take any risks – contact a professional. They’ll identify underlying issues and help you keep up with regular maintenance. That way, you can avoid missed comfort, costly repairs, and hefty energy bills. Pay attention to your furnace’s health and enjoy cozy warmth during winter!

Flame Sensor and Limit Switch Issues 

  • Short cycling is a common issue for homeowners, where the furnace starts and stops too quickly.
  • Flame sensor problems can contribute to short cycling as it is responsible for detecting the presence of a flame.
  • Limit switch issues can also cause short cycling as it prevents the furnace from overheating.
  • A dirty or broken flame sensor may fail to detect the flame, leading to short cycling.
  • A broken limit switch can shut off the furnace prematurely when it reaches excessive temperatures.
  • If your furnace is experiencing short cycling, it is recommended to call a professional technician rather than attempting to fix it yourself.
  • Some furnaces have a safety feature that blocks the furnace for 30-45 minutes before attempting to start again, preventing overheating.

New air filters can improve efficiency by up to 15%. Keep your filter in good condition for efficient heating and a clean indoor environment.

Contact an expert repairer if you think there’s an issue. It’ll help your furnace last longer, and keep you safe.

Signs of a Short Cycling Furnace

To identify the signs of a short cycling furnace with problems such as frequent starting and stopping, raw gas smell, loud bangs and overheating, and carbon monoxide leaks, you need to take into account a number of underlying issues. Each of these sub-sections points to a different cause that your furnace may require repairs or replacement for the safety, efficiency, and indoor comfort of your home. Let’s explore each of these signs and the potential issues that are causing them to occur.

Frequent Starting and Stopping

The signs of furnace short cycling, such as frequent starts and stops or inefficient heating, are unmistakable. This can cause extra strain on the unit, leading to costly repairs in the future. To avoid this, regular maintenance checks by professional HVAC technicians and appropriate usage habits are key.

Homeowners should be aware of the scent of raw gas, which is a tell-tale sign of short cycling. Plus, it puts Usain Bolt’s caffeine-high speed to shame. A dirty air filter or faulty thermostat can also cause high energy bills and temperature fluctuations.

Staying on top of furnace maintenance and usage will help ensure that your home stays warm and cozy for years to come.

Raw Gas Smell

If you smell raw gas coming from your furnace, that could be a sign of short cycling. Short cycling is when your furnace turns on and off frequently, which can cause damage and safety hazards. This issue is usually caused by faulty thermostat sensors or wiring. Clogged filters and limit switches may also be to blame. If left untreated, it could lead to more wear and tear and higher energy bills.

Don’t delay if you detect this raw gas smell or any other signs of short cycling. Get help from an experienced HVAC technician quickly. Don’t wait ’til it’s too late! Be aware of a furnace that sounds like a drum and is hotter than Zac Efron’s abs.

Loud Bangs and Overheating

Furnaces are essential – but not without faults. Beware of loud bangs and overheating if you suspect your furnace is ‘short cycling’. This is when it shuts off before completing a full heating cycle, leaving you with chilly results instead of warmth. Ignoring such signs may lead to costly replacements in the future.

A loud noise coming from the furnace could mean an issue with internal components like the motor or blower wheel. When air can’t circulate, the furnace overworks its parts – causing it to overheat, leading to early mechanical failure.

Fun Fact: The U.S. Department of Energy says replacing an old, inefficient heating system with a high-efficiency one may save up to 30% on utility bills.

Finding a carbon monoxide leak is like finding a needle in a haystack, except the needle could kill you.

Carbon Monoxide Leaks

Carbon monoxide leaks can be frighteningly dangerous. They are colorless and odorless, so hard to detect without the right equipment. A malfunctioning furnace can cause them. Exposure can cause headaches, nausea, dizziness, or even death.

Install carbon monoxide detectors in bedrooms and living areas. Test them regularly. Notice soot around the furnace area? Are smells coming from the appliance? Don’t wait for a catastrophe. Contact a professional right away.

Take action now! Regular furnace maintenance is a must. Protect your family’s safety. Schedule tune-ups with qualified technicians. Don’t let your furnace play games with your thermostat.

Ways to Prevent Short Cycling Furnace

To prevent short cycling in your furnace, regular maintenance by a professional HVAC contractor is key. Appropriate care of your air filter and proper thermostat settings can also go a long way. Ensuring proper ventilation, and cleaning your heat grates and vents are additional solutions. In this section, we will explore each of these sub-sections to help ensure your furnace does not start and stop excessively.

Regular HVAC Maintenance 

Keep your HVAC system in top shape! Clean the filters, ducts, and vents, and make sure all components are working. Neglecting maintenance can lead to overworking or breakdowns.

Pay attention to odd noises, smells, or performance. These could point to a problem that needs to be fixed soon.

Incorrect installation or sizing can also cause short cycling. Hire an experienced pro for correct installation and sizing.

Today, homeowners are aware of energy efficiency and cost savings. Don’t wait until it’s too late – invest in regular maintenance and avoid short cycling drama!

Appropriate Filter Care 

It’s essential to look after your furnace filter. A dirty filter means less airflow, forcing the furnace to work harder and for shorter periods of time, resulting in damage. Here are 4 steps for proper filter care:

  1. Check the filters monthly and replace them every 3 months.
  2. Opt for filters with a higher MERV rating, but not above system specifications.
  3. Throw out old filters and store new ones in a dry place, far from contaminants.
  4. Disposable electrostatic filters, like those recommended by Consumer Reports and Angie’s List, mustn’t be washed or vacuumed.

It’s also good to measure airflow in CFM to spot issues and see what needs to be improved.

Did you know? Over 70% of HVAC malfunctions come from bad maintenance, according to The Spruce experts. So, don’t mess with your thermostat – set it and forget it, unless you want to end up with a short cycling furnace and a long night of regret.

Proper Thermostat Settings 

Do your wallet a favor and adjust your thermostat settings right!

  1. Check if your furnace is compatible with programmable or smart thermostats.
  2. Set the temperature to your comfort level, but avoid big fluctuations.
  3. Avoid placing objects that generate heat near the thermostat.
  4. Consider upgrading to a zoning system that allows programming different temperatures in different parts of the house.
  5. By implementing a zoning system, you won’t need to keep adjusting the temperature manually.
  6. Regular maintenance of your furnace and thermostat can help detect issues before they worsen, ensuring optimal performance and efficiency.

My chum once faced inconsistent heating and hefty energy bills until he found out his faulty thermostat was causing short cycling

He switched to a programmable model that works with his furnace. Now, he has better control over the home’s temperature without adjusting it all the time. His energy bill was reduced drastically as well! Don’t suffocate your heating system, keep it functioning with the proper thermostat settings!

Ensuring Proper Ventilation

  1. Ensure proper ventilation for the furnace to work effectively. Sufficient air is required for combustion without interruption.
    • Insufficient air can lead to the release of carbon monoxide, a deadly gas that must be avoided.
  2. Schedule annual furnace maintenance with a professional.
    • Professionals will clean the filters to ensure smooth airflow.
    • Regularly clear away debris around the furnace.
  3. Maintain the recommended clearance between walls, vents, and units.
    • The right distance prevents dirt accumulation and excessive heat.
    • Proper clearance ensures adequate airflow to the combustion chamber.


Pro Tip: If your area gets dusty or has strong winds, consider adding mesh screens to your inlet hoods. This prevents blockage and lessens the need for thorough cleaning. Plus, it helps keep ventilation flowing, decreasing the chance of short cycling. Cleaning your heat grates and vents is useful too—you never know what you’ll find!

Cleaning Heat Grates and Vents

Our furnaces are essential for keeping our homes warm. But short cycling can lead to costly energy bills and damages. Cleaning heat grates and vents helps prevent this. Here’s an easy 6-step guide:

  1. Turn off your furnace.
  2. Carefully remove grates and vent covers.
  3. Vacuum or brush away dust and debris.
  4. Wipe tough stains with a mild detergent.
  5. Allow drying before replacing.
  6. Turn the furnace back on.

Also keep an eye out for air filter obstructions, clogged ducts, and the like. Don’t be like Karen down the lane; her system broke down due to clogging. Keep your heating system in check! Solve your furnace’s short cycling woes now.

Solutions for Short Cycling Furnace

To solve the issue of your short cycling furnace, it is essential to take a closer look at your malfunctioning components. Upgrading your HVAC system capacity will significantly reduce the cycling times and set the temperature to a limit that prevents overheating. Proper maintenance of your system will increase energy efficiency, and HVAC technicians can help repair and replace malfunctioning components. By improving energy efficiency with these solutions, you can make sure your furnace stops constantly starting and stopping while keeping an optimal indoor temperature.

Repair and Replacement of Malfunctioning Components 

Short cycling furnaces can be a bother. But fear not, you can repair or replace malfunctioning components to fix the issue! Here’s how:

  1. Check the thermostat is working properly.
  2. Clean the air filter – clogged ones can block airflow and cause short cycling.
  3. Check the limit switch – it should shut off the furnace if it overheats or malfunctions.
  4. Inspect the flame sensor – flames should stay lit, not frequently going out.
  5. Test the pressure switch – any defects could lead to it not opening or closing properly.
  6. Replace damaged components such as motor overload switches, control boards, relays, solenoids, inducer motors, gas valves, or thermostats.

Safety first! Turn off power sources before inspecting parts. Also, check the wiring circuit for loose connections.

Keep your furnace well-maintained for better performance and longer life. Don’t ignore signs! Delaying solutions will cost you more in repairs.

Don’t wait till it’s an emergency. Get regular maintenance checks so your heating system works at its best – call our experts today! Make sure your HVAC system capacity is up to scratch. No one wants a furnace that short cycles like an ex’s mood swings.

Upgrade HVAC System Capacity 

Fed up with short cycling furnaces? Upgrading your HVAC system capacity is the solution! It can boost efficiency and extend the life of your heating and cooling systems.

We’ve outlined 3 options for increasing HVAC system capacity:

  1. Upgrade to a bigger HVAC unit – this provides more heat and cooling but can be expensive ($6,000-$10,000+).
  2. Put in a 2nd HVAC system – this is a cost-effective option if you have multiple floors needing temperature control ($8,000-$12,000+).
  3. Upgrade ductwork/ventilation – this is cheaper than replacing a unit and can improve air circulation too ($4,000-$6,000+).

Not only does the upgrade resolve short cycling issues, but it also boosts indoor air quality. To further improve efficiency, seal any leaks or drafts around windows/doors. Investing in a smart thermostat can save up to 15% energy and help regulate temperature based on occupancy levels.

Follow these upgrades and you’re guaranteed a warm winter at an affordable cost – no more short cycling! Don’t forget, a little maintenance goes a long way – like a little duct tape can fix almost anything.

Improving Energy Efficiency with Maintenance and Upgrades 

  1. Regular furnace maintenance is essential for improving energy efficiency and keeping your home comfortable.
  2. Furnaces that frequently turn on and off, known as “short cycling,” lead to wasted energy, wear and tear, and discomfort.
  3. Proper airflow management is crucial for addressing short cycling issues. Ensure furnace filters are clean and free from debris.
  4. An HVAC professional can perform a pressure test on your ducts to identify and resolve airflow problems.
  5. Consider upgrading your thermostat to a programmable or smart one, allowing for greater control and energy savings.
  6. Regular maintenance is the best defense against short cycling furnaces. Schedule professional check-ups and cleaning for gas heaters after each season change.

If unsure of electrical problems, always reach out to a professional. Save your phone’s battery life and let the experts handle your short cycling furnace!

Contacting Professionals for Short Cycling Furnace

To resolve the issue of the short cycling furnace, contacting professionals would be the most apt solution. There are various experts and technicians with different specialties in the HVAC industry. A professional HVAC contractor could be a great option for furnace repairs and maintenance. Additionally, consulting with the Hart Home Comfort and Townsend Energy teams can help you identify the cause of the problem and provide necessary solutions to ensure the ideal performance and energy efficiency of your furnace.

HVAC Experts and Technicians

When your furnace is short cycling, it’s vital to contact HVAC professionals. They are specialists in heating, ventilation, and air conditioning systems. These experts have the expertise to diagnose and repair furnace issues quickly and effectively.

If it’s a faulty thermostat or blocked filter, HVAC pros can identify the cause of the issue and advise on how to fix it. You must call these specialists right away if you experience this issue, as a malfunctioning furnace can harm your health.

Moreover, getting help from HVAC professionals makes sure repairs meet safety standards and municipal codes. This way, you get durable solutions to short-cycling furnace problems.

Tip: Have annual maintenance visits with HVAC professionals. This helps avoid sudden system failures and extends the life of your furnace. For furnace repairs, don’t call your ex, call an HVAC Professional!

Professional HVAC Contractor

Furnace short cycling is a common issue that can affect the proper functioning of your HVAC system. A professional HVAC contractor can help. They have the know-how to diagnose furnace issues that could be causing short cycling. They offer customized solutions such as repair, replacement, and maintenance.

When talking to an HVAC contractor, it’s smart to explain the symptoms of the problem in detail. For example, telling them how often the furnace cycles help with diagnosis. They should also check ducts, vents, and other air components.

When choosing an HVAC contractor, look at qualifications and certification. Check online reviews and feedback to see if they are reliable. Look for a company that offers a one-time service or a maintenance plan at an affordable price.

Pro Tip: After you hire a contractor, request ongoing maintenance and inspections of your furnace. This is important for safety and helps spot any underlying problems early on, preventing significant damage or danger to people in the building.

For top-notch furnace services, Hart Home Comfort and Townsend Energy are the superheroes you need!

Consulting with Hart Home Comfort and Townsend Energy teams

Dealing with a short cycling furnace? It’s time to call in the pros! Hart Home Comfort and Townsend Energy teams are highly skilled and have the expertise to handle furnace problems. They provide prompt and efficient services that guarantee customer satisfaction.

These companies stand out from the rest; their commitment to quality and long-term solutions is second to none! A homeowner was frustrated with his short cycling furnace. After reading great reviews, he called Hart Home Comfort. The technician was there quickly and diagnosed the problem in minutes! With fair pricing, the homeowner was thrilled with the service he received.


If your furnace is short cycling, it can be really annoying and lead to energy waste. Reasons for this could be a dirty air filter, thermostat issues, or no airflow. Also, a malfunctioning sensor component could be the cause. To protect your furnace and keep it heating properly, it’s best to contact a professional HVAC contractor for repairs or replacement if needed. In the meantime, take a look at your air filter. If it’s dirty, replace it. Make sure your thermostat is set to the right temperature and that there isn’t anything blocking the vents and heat grates. If these don’t do the trick, you’ll need an HVAC expert like Hart Home Comfort and Townsend Energy. It’s very important to remember that short cycling can lead to raw gas being released into your home. This increases the risk of carbon monoxide poisoning and is dangerous. Additionally, short cycling can be caused by cracks in the heat exchanger. If this is the case, it’s important to call an HVAC professional right away.