How to Light Your Furnace: A Step-by-Step Guide
Facing a cold house and a furnace that won’t ignite can be frustrating. Modern furnaces often light automatically, but sometimes, due to various reasons like a power outage, gas supply interruption, or a malfunctioning component, they may require manual lighting. This comprehensive guide provides a detailed, step-by-step approach to safely and effectively light your furnace. However, **safety is paramount.** If you are uncomfortable with any of these steps or smell a strong gas odor, **immediately contact a qualified HVAC technician or your local gas company.**
**Disclaimer:** This guide is for informational purposes only and should not be considered a substitute for professional advice. Working with gas appliances can be dangerous. Proceed with caution and always prioritize safety. If you have any doubts, consult a qualified HVAC professional.
## Understanding Your Furnace
Before attempting to light your furnace, it’s crucial to understand the basic components and operation. Familiarize yourself with the following:
* **Gas Valve:** This valve controls the flow of gas to the furnace. It usually has an on/off switch or lever.
* **Pilot Light (for older furnaces):** A small, continuous flame that ignites the main burner. Many newer furnaces have electronic ignition systems instead of a pilot light.
* **Igniter (for newer furnaces):** An electronic component that heats up to ignite the gas. This can be a hot surface igniter (HSI) or a spark igniter.
* **Flame Sensor:** A safety device that detects the presence of a flame. If no flame is detected, it shuts off the gas supply to prevent gas buildup.
* **Burners:** The part of the furnace where the gas is burned to produce heat.
* **Blower Motor:** Circulates the heated air throughout your home.
* **Control Panel:** Contains the main controls and safety features of the furnace. It’s usually located behind an access panel.
* **Emergency Shut-off Switch:** Usually a red switch located near the furnace. Know where this is located in case of emergency.
## Safety Precautions
* **Never smoke or use open flames while working near a gas appliance.**
* **Ensure proper ventilation.** Open windows and doors to allow fresh air to circulate.
* **If you smell gas, do not attempt to light the furnace.** Evacuate the building and call your local gas company from a safe location.
* **Use a long-handled lighter or match holder to avoid getting your hand too close to the burner.**
* **Wear safety glasses to protect your eyes.**
* **Always follow the manufacturer’s instructions.** Consult your furnace owner’s manual for specific instructions and safety precautions.
* **Turn off the power to the furnace** before beginning any maintenance or repair work (unless specifically instructed otherwise for troubleshooting).
## Tools and Materials You May Need
* Long-handled lighter or match holder
* Screwdriver (for removing access panels)
* Flashlight
* Owner’s manual for your furnace
* Wrench (possibly, for loosening gas line connections – only attempt this if you are very comfortable and know what you are doing; otherwise, call a professional)
## Step-by-Step Instructions: Lighting a Furnace with a Pilot Light (Older Furnaces)
This method applies to older furnaces equipped with a pilot light. If your furnace has an electronic ignition, skip to the next section.
1. **Turn Off the Furnace:** Locate the gas valve on the furnace. It’s usually a knob or lever. Turn it to the “OFF” position. This shuts off the gas supply to the furnace.
2. **Wait for Five Minutes:** This allows any accumulated gas to dissipate. It’s a crucial safety step.
3. **Locate the Pilot Light Assembly:** This is usually located near the burners. You may need to remove an access panel to see it. Consult your owner’s manual for the exact location.
4. **Turn the Gas Valve to “Pilot”:** On the gas valve, you should see markings for “ON,” “OFF,” and “PILOT.” Turn the valve to the “PILOT” position. You may need to push down on the valve while turning it to the “PILOT” position and hold it down.
5. **Light the Pilot Light:** While holding the gas valve in the “PILOT” position, use a long-handled lighter or match to ignite the pilot light. You should see a small, steady flame. Some furnaces have a push-button igniter; press this button repeatedly while holding the gas valve in the “PILOT” position.
6. **Hold the Gas Valve for 30-60 Seconds:** Continue holding the gas valve in the “PILOT” position for 30-60 seconds. This allows the thermocouple (a safety device that senses the pilot light flame) to heat up. If the thermocouple doesn’t heat up sufficiently, it will shut off the gas supply.
7. **Release the Gas Valve:** After 30-60 seconds, release the gas valve. If the pilot light stays lit, proceed to the next step. If the pilot light goes out, repeat steps 4-6. If it consistently fails to stay lit, there may be a problem with the thermocouple, gas valve, or gas supply. Contact a qualified HVAC technician.
8. **Turn the Gas Valve to “ON”:** Once the pilot light is burning steadily, turn the gas valve to the “ON” position.
9. **Turn on the Furnace:** Flip the switch on the furnace to the “ON” position or restore power to the furnace if you turned it off at the breaker. Set your thermostat to the desired temperature.
10. **Observe the Burners:** The main burners should ignite automatically. If they don’t, turn off the furnace and contact a qualified HVAC technician.
## Step-by-Step Instructions: Lighting a Furnace with Electronic Ignition (Newer Furnaces)
Newer furnaces use electronic ignition systems, which eliminate the need for a standing pilot light. There are two main types: hot surface igniters (HSI) and spark igniters.
1. **Turn Off the Furnace:** Locate the gas valve on the furnace. Turn it to the “OFF” position.
2. **Wait for Five Minutes:** Allow any accumulated gas to dissipate.
3. **Turn On the Furnace:** Turn the gas valve to the “ON” position.
4. **Set the Thermostat:** Set your thermostat to a temperature above the current room temperature to call for heat.
5. **Observe the Ignition Sequence:** The furnace should now begin its ignition sequence. Listen carefully. You should hear a clicking sound (for spark igniters) or see the igniter glowing orange (for hot surface igniters).
6. **Burner Ignition:** After a few seconds, the main burners should ignite. If they do, the furnace is working properly. You should feel warm air coming from the vents.
7. **Troubleshooting Ignition Problems:** If the burners don’t ignite, the furnace may attempt the ignition sequence several times before going into a lockout mode. If this happens, turn off the furnace, wait a few minutes, and try again. If it still doesn’t work, consult the troubleshooting section below.
## Troubleshooting Furnace Problems
If your furnace doesn’t light properly, consider these common issues:
* **No Gas Supply:**
* **Check the gas meter:** Ensure the gas meter is turned on. If you’ve recently had work done on your gas lines, the meter may have been turned off.
* **Check other gas appliances:** See if other gas appliances in your home (e.g., stove, water heater) are working. If none of them are working, there may be a problem with your gas supply.
* **Pilot Light Won’t Stay Lit (Older Furnaces):**
* **Dirty pilot light orifice:** A clogged orifice can restrict gas flow to the pilot light. A qualified technician can clean the orifice.
* **Faulty thermocouple:** The thermocouple may be faulty and not generating enough voltage to keep the gas valve open. A technician can test and replace the thermocouple.
* **Weak pilot light flame:** A weak flame may not be heating the thermocouple sufficiently. This could be due to low gas pressure or a dirty pilot light orifice.
* **Burners Won’t Ignite (Electronic Ignition Furnaces):**
* **Faulty igniter:** The igniter may be broken or not heating up properly. A technician can test and replace the igniter.
* **Dirty flame sensor:** The flame sensor may be covered in soot or debris, preventing it from detecting the flame. Clean the flame sensor with fine steel wool or a wire brush. Be gentle!
* **Faulty gas valve:** The gas valve may not be opening to allow gas to flow to the burners. A technician can test and replace the gas valve.
* **Blocked burner:** The burner may be blocked with debris, preventing proper ignition. A technician can clean the burner.
* **Furnace Cycles On and Off Frequently (Short Cycling):**
* **Dirty air filter:** A dirty air filter restricts airflow, causing the furnace to overheat and shut down prematurely. Replace the air filter regularly.
* **Oversized furnace:** If the furnace is too large for your home, it may heat up the house too quickly and then shut off, resulting in short cycling.
* **Faulty thermostat:** A faulty thermostat may be sending incorrect signals to the furnace.
* **No Airflow:**
* **Blower motor failure:** The blower motor may be broken or not receiving power. A technician can diagnose and repair or replace the blower motor.
* **Blocked vents:** Make sure all vents are open and not blocked by furniture or other objects.
* **Ductwork problems:** Leaky or damaged ductwork can reduce airflow.
## Regular Furnace Maintenance
Preventive maintenance is key to keeping your furnace running efficiently and safely. Here are some essential maintenance tasks:
* **Change the Air Filter Regularly:** Replace the air filter every 1-3 months, depending on the type of filter and the air quality in your home. A clean air filter improves airflow and protects the furnace components from dust and debris.
* **Inspect the Burners:** Visually inspect the burners for any signs of rust, corrosion, or debris. Clean the burners if necessary. However, if you are not comfortable doing this yourself, call a professional.
* **Clean the Flame Sensor (for electronic ignition furnaces):** Clean the flame sensor annually with fine steel wool or a wire brush. This ensures that the sensor can accurately detect the flame.
* **Check the Flue Pipe:** Inspect the flue pipe (the pipe that vents exhaust gases outside) for any signs of rust, corrosion, or leaks. A blocked or damaged flue pipe can lead to carbon monoxide poisoning.
* **Schedule Professional Maintenance:** Have your furnace professionally inspected and serviced annually by a qualified HVAC technician. A technician can perform a thorough inspection, clean and lubricate components, and identify any potential problems before they become major issues.
## When to Call a Professional
While this guide provides helpful information, certain situations require the expertise of a qualified HVAC technician. Call a professional if:
* You smell a strong gas odor.
* You are uncomfortable working with gas appliances.
* The furnace consistently fails to light.
* You suspect a gas leak.
* The furnace is making unusual noises.
* You are experiencing carbon monoxide symptoms (headache, dizziness, nausea).
* You are not comfortable performing any of the maintenance tasks described in this guide.
## Carbon Monoxide Safety
Carbon monoxide (CO) is a colorless, odorless, and deadly gas produced by the incomplete combustion of fuels, such as natural gas. A faulty furnace can leak CO into your home. **It is essential to have working carbon monoxide detectors installed on every level of your home, especially near sleeping areas.**
* **Test your carbon monoxide detectors regularly.**
* **Replace your carbon monoxide detectors every 5-7 years.**
* **If your carbon monoxide detector alarms, evacuate the building immediately and call 911.**
## Conclusion
Lighting a furnace can seem daunting, but by following these detailed steps and safety precautions, you can often get your furnace up and running again. Remember to prioritize safety and never hesitate to call a qualified HVAC technician if you are unsure about anything. Regular maintenance and carbon monoxide detection are essential for ensuring the safe and efficient operation of your furnace.
By understanding the components of your furnace, following safety guidelines, and performing regular maintenance, you can keep your home warm and comfortable throughout the heating season. Always remember, when in doubt, call a professional!
This comprehensive guide will help you safely troubleshoot and, if possible, relight your furnace. Remember that consulting with a qualified HVAC professional can often save time and money while ensuring the safety of your home and family. Good luck, and stay warm!