What It Means When Your Furnace Flame Turns Orange, Red, or Yellow

If you have a natural gas furnace in your Baltimore, Maryland home, its furnace flame should always be blue. A blue furnace flame that has a lighter blue triangle at its center is an indication of good fuel combustion. Although you might see small tinges of yellow at the flame’s tip, having your furnace flame turn completely orange is a problem. Read on to find out why.

Issues at the Fuel Burner

Issues with fuel combustion can cause your furnace flame to turn completely yellow, orange, or red. More often than not, this change in color is a sign of issues at the fuel burner. If the burner isn’t receiving adequate airflow, it can’t burn natural gas completely. Even during normal furnace operations, incomplete fuel combustion creates harmful gases like carbon monoxide. To keep building residents safe, all gas-fired appliances are vented outdoors.

However, when furnace burners malfunction and furnace flames change color, the excess exhaust gases that are produced may not make it outside. If CO gas enters the home, residents can experience uncomfortable symptoms of carbon monoxide exposure including:

  • Headaches
  • Fatigue
  • Nausea
  • Confusion
  • Chest pain
  • Dizziness
  • Vomiting

If CO exposure is prolonged, it can lead to severe carbon monoxide poisoning and even death.

It’s additionally important to note that CO isn’t the only harmful exhaust gas that can enter your home when your furnace flame is yellow. Building residents can also be exposed to:

  • Polycyclic aromatic hydrocarbons
  • Nitrogen oxides
  • Sulphur oxides
  • Soot

Unfortunately, unlike CO gas, there aren’t residential alarms that are capable of detecting these toxins. Although carbon monoxide exposure can be downright deadly, these secondary contaminants can also have a major impact on both your indoor air quality and your health.

The Lesser Consequences of Having a Yellow Furnace Flame

Even if excess exhaust gases are routed outside when your furnace flame turns yellow, incomplete fuel combustion can affect you in other ways. When your furnace flame is yellow, your furnace has to burn more fuel to produce less heat. This means that your home energy bills will rise even as resident comfort declines. This can lead to both longer heating cycles and more of them. The extra work that your furnace performs can take a serious toll. In fact, it may set the stage for major repair issues and shorten your furnace’s lifespan.

Other Signs That Your Furnace Isn’t Burning Fuel Properly

If your furnace keeps triggering your CO alarms, you should turn your heating system off and have it professionally inspected before using it again. It’s also a good idea to exit the building until you know for certain that your home is clear of this toxic gas. Carbon monoxide is both colorless and odorless. There’s no way to detect it apart from having CO alarms installed and keeping their batteries charged. Thus, if you have a gas-fired furnace in your home, regularly checking and maintaining your CO alarms is absolutely essential. Incomplete fuel combustion can happen at any time.

There are other tell-tale signs of combustion problems that you can check for. For instance, there may be buildups of soot around your furnace. Not only is this an indication that your furnace is burning fuel incompletely, but it’s also a sure sign of exhaust gases entering the home.

If your flame is blue but has an increasingly large, yellow tinge at its edges, pay attention to how the flame moves. Furnace flames should be both blue and steady. Constant guttering, wavering, and flickering are indications of trouble as well. If your furnace flame has both a slight yellow tinge and an irregular flame pattern, contact an HVAC company.

Backdrafting and Incomplete Fuel Combustion

For many years, the most common cause of yellow furnace flames was burner problems due to insufficient furnace maintenance. Today, this is still one of the top causes. However, increasingly tight home envelopes are rising to take its crown. As homeowners rush to make their properties evermore efficient, residential buildings are becoming increasingly airtight. This minimizes heat loss during winter, lowers home energy bills, and decreases carbon footprints. It also sets the stage for potentially dangerous air pressure issues.

In winter, when homes are sealed up tight, exhaust fans and other fixtures and devices that move air outdoors are in operation. Your household might be running the stove’s vent hood exhaust fan, your bathroom exhaust fan, and your fireplace all at once. Surprisingly fireplaces are always exhausting air even when they aren’t being actively used. Constantly removing air from an already airtight environment eventually depressurizes it. This can cause exhaust gases to get pulled back down chimneys and vents.

If your furnace happens to turn on during the middle of this backdrafting activity, your furnace flame will gutter and waver, and it will likely turn yellow. Backdrafting prevents furnace burners from getting the oxygen they need to burn the fuel completely. Worse still, once backdrafting occurs, it can be incredibly difficult to reverse. Unless homeowners understand what’s happening, they won’t be able to resolve the problem on their own. Restoring adequate airflow into the building is the only way to reverse and prevent this problem.

There May Be Issues at Your Chimney or Vent

If burner issues aren’t the cause of your yellow or orange furnace flame, and if your home envelope isn’t causing backdrafting, the culprit could be your furnace’s vent or chimney. Venting systems are a critical part of safe furnace operation, and they must be correctly designed, installed, and maintained. If furnace vents are too big or too small for their intended application, they cannot consistently maintain a sufficient draft. They’ll also impact fuel combustion if they’re blocked, dirty, covered in corrosion, or poorly insulated.

There Could Be Critters

In winter, exhaust vents and chimneys can seem like wonderful homes to various critters. After all, these spaces are warm, enclosed, and often easy to get into. A yellow, guttering furnace flame may simply be a sign that you’ve got a bird’s nest in your furnace vent, or that it’s been blocked by a dying or dead animal. Vent blockages can also be the result of structural obstructions such as collapsed brickwork or damaged liners. In many instances, structural damage on the interior of furnace vents is the result of pests as well.

How to Avoid Having Your Furnace Flame Burn Yellow

Scheduling routine furnace maintenance is the absolute best way to keep your furnace flame a bright, healthy blue. Venting systems and furnace burners are both carefully assessed during these appointments. Although having an airtight home definitely prevents both heat loss and energy waste, making sure that your home envelope isn’t too tight will prevent backdrafting. Finally, make sure that all vents and chimneys are properly covered. If you leave animals with an easy point of ingress, they will eventually find their way in.

At At Your Service Heating & Cooling LLC, we’ve been proudly serving residents of the greater Baltimore, MD area since 2013. We provide heating, cooling, and plumbing service. We also offer backup generators and preventative maintenance plans. If your furnace flame is an odd color or has an abnormal pattern, contact At Your Service Heating & Cooling LLC right away.

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