How to Relight and Troubleshoot Your Gas Furnace

Relighting Gas Furnace in O'Fallon, MO

A pilot light system is an essential component of a gas heating system. There are many different types of ignition systems today. Here are some tips on how to relight your furnace and troubleshoot the pilot light.

Standing vs. Automatic Ignition Furnace

Before relighting, it is essential to understand the type of ignition system in your furnace. The two main categories are electronic and the standing pilot light.

The standing pilot light is often found in equipment made before the 1990s. The pilot will burn for as long as it detects heat from the pilot light. When the flame goes out, a safety mechanism shuts off the gas supply.

Since the pilot light has to burn round the clock, it requires a continuous gas supply to keep the flame lit. Estimates suggest it can consume up to 800 BTU/hour, which amounts to hundreds of dollars in utility bills.

A standing pilot light is more practical for places with colder climates. St. Louis experiences freezing weather for three months every year. Therefore, it is more convenient to keep the flame lit. But in warmer weather, the pilot light will be on when no heating is required. That means it will waste energy.

Electronic ignition is much more economical, as it cuts off the gas supply as soon as the flame is on. Automatic systems employ a sparking mechanism and do not blow out as readily as the standing pilot light.

However, automatic systems are more sophisticated in design and require expertise to fix. They also have varying mechanisms, depending on your model. At Hoff Heating & AC, we recommend calling experienced furnace technicians whenever you have a problem in Chesterfield.

Identify Parts of a Pilot Light

You can locate the ignition system below the furnace’s access cover. Look for a button labeled “on,” “off,” and “Pilot” at the bottom of the burner assembly. You may also see a big tube and two smaller ones when you remove the furnace cover.

The two smaller tubes lead to the pilot light system. The thermocouple has to be on the hottest part of the assembly. So it usually sits right next to the pilot light. When the pilot light is on, it should be burning with a blue flame.

Furnaces vary in design, but the procedure for lighting a pilot flame is more or less the same. You can always consult the equipment’s manual if you are unsure how to light the furnace. Otherwise, you can talk to Hoff Heating & AC professionals for reliable furnace repair services in Chesterfield.

Relighting a Standing Pilot Light

Start by switching off your furnace gas supply for a few minutes. That will allow gas that is usually flowing through the pilot tube to dissipate.

Locate the gas control knob and turn it to the “pilot” setting. Some systems have a spark ignition, while others will require a match or a lighter.

For spark systems, hold down the ignition button until the flame lights up. Turn on the lighter or match, and it will light immediately. Continue holding down the button for about 30 seconds and release.

If the pilot light switches off after a few minutes, relight it again. Repeat the process, starting with switching off the gas supply.

Confirm the pilot light is still on by adjusting thermostat settings to heat. The furnace should light up normally. If it does not start, you should switch off the system and consult an experienced professional.

Standing Pilot Light Issues

You can tell a standing pilot light is efficient if it produces a clear blue flame. It indicates the combustion is burning at the optimal air to the gas mixture. That means it generates heat while using as little fuel as possible.

However, if you spot a yellow flame, it could be a sign of inefficient combustion. Your furnace can produce carbon monoxide gas. CO poisoning has symptoms such as fatigue, headaches, and nausea.

Before you conclude your furnace is faulty, you should rule out drafts. One of the most common reasons for a yellow pilot light is a breeze. So, ensure the furnace cover is secure in place.

Another way you can address the yellow flame is to adjust the pilot light valve. You can turn the knob slowly until the color turns back to clear blue. Be careful while handling the valve, and follow the manufacturer’s instructions.

The pilot light tube has deposits of debris that are interfering with the gas-to-air mixture. A professional can clean the pilot system to restore the flame. At Hoff Heating & AC, we recommend maintenance before winter to prepare your furnace for Chesterfield’s winter.

Troubleshooting an Automatic Ignition Furnace

Some modern furnaces still use a pilot light but with electronic ignition. The pilot system is in a sealed compartment, so you can’t use a match to light it. However, the process is similar to a conventional pilot light system.

The thermostat signals the pilot system to light. A flame sensor detects if the flame, and only then does it allow gas into the furnace’s burner.

An intermittent ignition pilot utilizes electricity to produce the flame. The flame turns off as soon as the furnace switches on. There is no need to keep the pilot light burning. Therefore, they are less prone to issues such as insufficient combustion.

However, a problem can develop due to an improper thermostat connection. It could be an issue with a defective electric spark, or the gas pipe is out of position. Just as with traditional systems, grime and dirt can affect the ignition process.

Another type of electronic system is the hot surface ignition. It works on the same principle as an incandescent bulb. It produces the flame by passing an electric current through two thin strips until they heat to the desired temperature.

If your furnace has a hot surface ignition, it can fail due to dirt accumulation on the filament. Even a fingerprint smudge can prevent the system from lighting. A routine tune-up can ensure your equipment is efficient throughout the season.

Additionally, the filament casing can fracture due to exposure to very high and low temperatures. When there is cracking, the ignition struggles to reach the required temperatures.

It is also worth noting that an electronic system is designed to start immediately to avoid hazards. You may notice a bang when switching on the system. It is usually a sign of delays causing gas to accumulate to unhealthy levels. Seek a certified technician to repair the issue promptly as it is dangerous for occupants in your home.

The best way to prevent malfunctions in winter is to stick to your annual maintenance routine. During maintenance, professionals can spot issues before they cause damage or pose a risk for your family. You can keep your system efficient and manage energy consumption better. We recommend scheduling a tune-up once a year preferably, in the fall.

When your furnace breaks down, you can rely on Hoff Heating & AC prompt and dependable services in Chesterfield. We can fix a wide range of heating equipment, including high-efficiency furnaces and heat pumps. You can also count on us for all of your cooling needs. Our BBB accredited team will complete the repair tasks quickly and restore your equipment. As Lennox Premier Dealers, we are bound by the highest standards of service. You can contact our team today for more details on our service.