Question 1

Why is my furnace blowing cold air?

Accepted Answer

If your furnace blower is running but the air coming out of your vents is cold, it means the burners are not igniting or staying lit. The first thing to check is your thermostat; ensure it is set to "heat" and the temperature is set higher than the current room temperature. If the thermostat settings are correct, the problem lies within the furnace itself. The system is designed so the blower will continue to run for a period even if the burners fail to light. This is a safety measure to clear out any unburnt fuel.

The most common reason for this issue is a problem in the ignition sequence. A dirty flame sensor is a frequent culprit. If the flame sensor is coated in carbon buildup, it cannot detect the flame, and it will shut the gas valve off as a safety precaution. Another common cause is a failed hot surface ignitor. This is the part that glows bright orange to light the gas; if it is cracked or burned out, the furnace will not ignite. A problem with the gas valve or the furnace's control board can also prevent the burners from lighting.

On older furnaces, the problem could be an extinguished pilot light that simply needs to be relit. However, for most modern furnaces, the issue requires a professional technician to diagnose. They will test each component of the ignition system to find the exact point of failure. Continuing to cycle the furnace on and off when it is blowing cold air can cause unnecessary strain on the components. It is best to call for a professional repair to get the problem resolved safely and correctly.

Question 2

How much does it cost to fix a furnace?

Accepted Answer

The cost to fix a furnace varies widely and is entirely dependent on which part has failed. Many common repairs are relatively affordable. For example, cleaning a dirty flame sensor or replacing a faulty hot surface ignitor are common jobs on the lower end of the cost spectrum. These are parts that frequently wear out and are not typically expensive to replace. Our technicians can often perform these repairs quickly with parts carried on their service vehicle. Our goal is to provide the most cost-effective solution possible.

The repair cost increases for more significant component failures. Replacing a blower motor or an inducer motor is a more involved job with a higher price point. The same is true for replacing a gas valve or a primary control board. These parts are more expensive, and the labor required to replace them is more extensive. Our technician will always provide you with an upfront quote for these larger repairs before any work begins. This allows you to weigh the cost of the repair against other options.

The most serious diagnosis is a cracked heat exchanger. This is a critical safety failure, and the component itself cannot be repaired. A cracked heat exchanger requires a full furnace replacement, which is a major investment. To determine an accurate cost for any repair, a professional diagnosis is essential. We charge a standard diagnostic fee to come to your home, identify the problem, and provide you with a firm, upfront price for the repair. This fee is often applied to the repair cost if you proceed with our service.

Question 3

My furnace keeps turning on and off, what's wrong?

Accepted Answer

When a furnace turns on for a short period, shuts off, and then repeats the cycle, it is a condition known as short cycling. The most common cause of short cycling is a dirty or clogged air filter. A clogged filter severely restricts airflow through the furnace. This lack of airflow causes the furnace's heat exchanger to get too hot. A safety device called the high-limit switch senses this overheating and shuts the burners off. The fan will continue to run to cool the unit down, and then the furnace will try to start again, repeating the cycle.

Before calling for service, you should always check your air filter. If it is visibly dirty, replacing it may solve the short cycling issue. If a new filter does not fix the problem, the cause is likely more serious. The issue could be a malfunctioning high-limit switch that is tripping prematurely. It can also be caused by a faulty thermostat that is not reading the room temperature correctly. Blocked air vents or a problem with the blower motor can also lead to insufficient airflow and cause short cycling.

In some cases, short cycling can be a sign that the furnace is oversized for your home. An oversized furnace will heat the space so quickly that it shuts down before completing a proper heating cycle. This is inefficient and causes excessive wear on the furnace's components. Our technicians can properly diagnose the root cause of the short cycling. We will determine if it is a simple airflow issue, a failing part, or a sizing problem.

Question 4

What does a yellow furnace flame mean?

Accepted Answer

A healthy and efficient furnace flame should be a consistent, bright blue color. If you look through the observation window on your furnace and see a flame that is yellow or orange, it is a clear sign of a problem. A yellow flame indicates that the furnace's burners are dirty or that there is an issue with the gas-to-air mixture. This results in incomplete combustion of the fuel. This is not a problem that should ever be ignored, as it signifies that your furnace is not operating safely or efficiently.

An incomplete combustion process, indicated by a yellow flame, produces higher levels of carbon monoxide. It also creates soot, which can build up on the heat exchanger. This layer of soot acts as an insulator, reducing the furnace's efficiency and making it work harder to heat your home. This means you are paying more for fuel while also operating the system in an unsafe condition. The problem is typically caused by dirty burners that are not allowing gas and air to mix properly. It is a clear signal that your furnace is in immediate need of professional service.

If you notice a yellow flame, you should schedule a furnace maintenance or repair visit right away. A technician will need to remove and thoroughly clean the burner assembly. They will also check the gas pressure and make any necessary adjustments. Do not continue to operate a furnace with a yellow flame. This is one of the most visible warning signs your furnace can give you that it requires professional attention to restore its safety and efficiency.

Question 5

Why did my furnace stop working completely?

Accepted Answer

If your furnace has stopped working completely, there are a few simple things to check before calling for service. First, check the circuit breaker for the furnace in your home's main electrical panel. If the breaker has tripped, you can try resetting it one time. If it trips again, do not reset it and call a professional. You should also check for a power switch on or near the furnace itself; sometimes these can be accidentally turned off. Finally, check the batteries in your thermostat if it uses them. A simple check can sometimes save you a service call.

If those simple checks do not resolve the issue, the problem is likely a failed component within the furnace. A common cause for a total failure is a burned-out transformer. The transformer is a small part that converts high voltage electricity from your home to a lower voltage to operate the furnace's controls. If it fails, the entire system will be dead. A failure of the main control board, the "brain" of the furnace, will also result in a complete shutdown. These electrical issues require a professional diagnosis.

Another possibility is a failure of the main blower motor. Some furnaces will not attempt to start the heating cycle at all if the control board detects that the blower motor is not working. The system knows that without the blower, it would immediately overheat, so it will not even try to ignite. A technician can test the blower motor, its capacitor, and the control board to determine where the failure has occurred. Our team is equipped to diagnose and repair any of these "no power" situations.

Question 6

What is a furnace flame sensor and why does it fail?

Accepted Answer

A furnace flame sensor is a critical safety device found in nearly all modern gas furnaces. It is a small metal rod that is positioned in front of one of the burners. Its only job is to detect that a flame is actually present after the gas valve has opened. If the flame sensor detects a flame, it sends a tiny electrical signal to the control board, and the furnace continues to run. If it does not detect a flame, the control board will shut the gas valve off within a few seconds. This prevents the furnace from pumping raw, unburnt gas into your home.

Flame sensors are one of the most common failure points in a furnace, but they do not usually "fail" in the traditional sense. Over time, the rod becomes coated with a nearly invisible layer of carbon buildup from the combustion process. This carbon layer acts as an electrical insulator. It prevents the sensor from being able to send its signal to the control board. The control board then thinks there is no flame, even when there is one, and shuts the furnace down as a safety precaution. This is the most frequent cause of a furnace that lights for a few seconds and then turns off.

The repair for a faulty flame sensor is often quite simple and affordable. In most cases, a technician can remove the sensor and carefully clean the carbon buildup off the metal rod using a soft abrasive pad. Once it is clean, it can be reinstalled, and the furnace will operate correctly again. In some cases where the porcelain insulator on the sensor is cracked, the part may need to be replaced entirely. This is a quick and common repair that our technicians perform on a daily basis during the winter.

Question 7

Should I repair or replace my old furnace?

Accepted Answer

Deciding between repairing and replacing an old furnace is a major decision that depends on three key factors. The first factor is the age of your furnace. If your furnace is over 15 years old, it is nearing the end of its expected service life. Investing in a major repair for a unit this old is often not a wise long-term decision. An older furnace will be significantly less efficient than a new model and is at a high risk of other components failing in the near future. Age is a very strong indicator that replacement should be seriously considered.

The second factor is the cost and nature of the required repair. A good rule of thumb is to consider replacement if the cost of a repair is 50 percent or more of the cost of a new furnace. For example, putting $1,500 into repairing a 15-year-old furnace is rarely a good investment. If the required repair is for a critical component like a cracked heat exchanger or a failed control board, replacement often makes more sense. These major repairs on an old unit are often just the first of many to come.

The final factor to consider is the efficiency of your old unit. An old furnace from 15 years ago might have an AFUE rating of 70% or 80%. A new high-efficiency furnace can have an AFUE of 95% or higher. Upgrading can lead to a dramatic reduction in your monthly heating bills. These long-term energy savings can help to offset the cost of the new furnace over its lifespan. Our technicians will always provide you with an honest assessment. We will give you the repair cost and the replacement cost so you can make an informed choice.

Question 8

What should I do if I smell gas near my furnace?

Accepted Answer

If you smell gas in your home, especially a strong odor of rotten eggs near your furnace, you must act immediately. This situation indicates a potential gas leak, which is extremely dangerous. Your first priority is to get everyone out of the house right away. Do not waste any time gathering belongings. When leaving, do not turn any lights on or off, and do not use your phone or any other electronic device inside the house. A tiny spark from a light switch or electronic device could be enough to ignite the gas and cause an explosion.

Once everyone is safely outside and a safe distance away from the house, you need to make two phone calls. The very first call should be to your local gas company's emergency number. You can find this number on your utility bill or by searching for it online from your safe location. Inform them that you smell gas and give them your address. They will dispatch a crew immediately to shut off the gas supply to your home and make the area safe. Do not re-enter your home for any reason until the gas company has declared it safe.

After you have called the gas company, your second call should be to SWVA Mechanical for an emergency furnace repair. Once the gas company has turned the gas off and secured the area, one of our technicians will need to find and repair the source of the leak within your furnace or its connections. A gas leak is one of the most serious emergencies a homeowner can face. Following these steps carefully is critical for protecting your family and your property. Your safety is the only thing that matters in this situation.

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