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How to Check Furnace Gas Valve with Multimeter? Guide of 2024

Your home's furnace is vital to keeping your family warm and comfortable, especially during cold seasons. Within this essential appliance, there's a tiny but crucial component called the furnace gas valve.

To check the furnace gas valve with a multimeter: turn off power, disconnect wires, set multimeter to "mV," test terminals. Normal reading: 145-195 millivolts. Outside range signals a defective valve. Furnace gas valves cannot be repaired.

The furnace is responsible for regulating the gas flow to the furnace's burner, which produces the heat you need. Ensuring this gas valve is working correctly is not just about having a cozy home; it's also about safety. You should learn how to check furnace gas valve with multimeter.

What is a Furnace Gas Valve?

The furnace gas valve controls the flow of natural gas or propane to your furnace's burner. When your home needs heat, the gas valve opens, letting the gas flow to the burner, creating the warmth you enjoy. It's a small part, but it plays a massive role in keeping your home cozy.

Why is it Important to Check the Gas Valve?

Now, you might wonder, why bother checking this seemingly insignificant valve? Well, here's the deal: if the gas valve isn't working correctly, your furnace won't be able to produce heat efficiently. This means your home might not get warm enough, especially during chilly nights. But that's not the only concern.

how to check furnace gas valve with Multimeter

A malfunctioning gas valve can lead to more significant problems, including gas leaks. Gas leaks are dangerous because natural gas is flammable. In extreme cases, it can cause explosions, which pose a significant risk to your home and your family's safety. Regularly checking the gas valve ensures your furnace operates efficiently and, more importantly, safely.

How to Check Furnace Gas Valve with Multimeter | Step-By-Step Guide

So, how to check furnace gas valve with multimeter? Let's get to the practical part: checking your furnace's gas valve using a multimeter. A multimeter is a device that measures electrical voltage, something we need to understand the gas valve's condition.

Step#1. Turn off the Main Supply to the Furnace: 

Safety first! Always initiate by turning off the gas supply to your furnace. This step ensures you're working in a safe environment.

Step#2. Remove the Panel to the Furnace Gas Valve: 

Carefully remove the access panel that covers the gas valve. Manufacturers usually place this panel on the front of the furnace. Use the correct tools and be gentle to avoid damaging it.

Step#3. Locate the Gas Valve Terminals: 

How to Check Furnace Gas Valve with Multimeter

Inside are the gas valve terminals. These are the spots where electrical connections are made. They're usually labeled, so they're relatively easy to find.

Step#4. Set the Multimeter to the DC Voltage Setting: 

Now, prepare your multimeter. Set it to measure DC voltage. This setting ensures you're measuring the right type of electrical flow the gas valve uses.

Step#5. Touch the Multimeter Probes to the Gas Valve Terminals: 

With the multimeter set correctly, gently touch its probes to the gas valve terminals. This action completes an electrical circuit, allowing the multimeter to measure the voltage through the gas valve.

Step#6. Read the Voltage Reading on the Multimeter: 

Look at the multimeter's display. It will show you the voltage reading. This number is your key to understanding the gas valve's condition.

Read more about Best Multimeters For Low Voltage

Interpretation of Results:

  • If the Voltage Reading is Equal to the Supply Voltage: Normal reading should be 145-195 millivolts. If the multimeter shows a reading that matches the supply voltage specified in your furnace's manual, your gas valve is doing its job correctly. No electrical problems exist, and your furnace should be heating your home efficiently.
  • If the Voltage Reading is Lower than the Supply Voltage: If the reading is lower than the specified 145-195 millivolts supply voltage, it's a sign that something might be wrong with the gas valve. In this case, seeking further inspection or professional help is best. Sometimes, minor issues can escalate if not addressed promptly.
  • If the Voltage Reading is Zero: A reading of zero volts indicates a clear problem. Your gas valve isn't receiving any electrical power, rendering it non-functional. Replacement or repair is necessary to get your furnace back in working order. Now you know - how to check furnace gas valve with multimeter?

Safety Precautions

Safety is paramount when dealing with gas appliances and electrical components. Here are some essential precautions to keep in mind:

Safety Precautions when checking furnace gas valve

1. Avoid Touching Live Electrical Wires: While checking the gas valve, be aware of other electrical components inside the furnace. Avoid touching any live wires to prevent electric shocks. Safety should always be your top priority.

2. Contact a Qualified Technician if Uncomfortable: If you're not comfortable or experienced in dealing with gas valves and electrical connections, it's best to call a professional technician. These experts have the necessary skills and tools to handle the inspection, ensuring your safety and the optimal performance of your furnace.

Signs of a Faulty Gas Valve: Recognizing Problems for a Safe Home

Your home's heating system, particularly the furnace, relies on several components to function efficiently. Among these, the gas valve holds a pivotal role.

It controls the flow of natural gas or propane, regulating the heat production essential for keeping your home warm. When the gas valve malfunctions, it affects your comfort and poses significant safety risks.

1) Irregular Heating Patterns

One of the most obvious signs of a faulty gas valve is irregular heating patterns in your home. If some rooms are toasty while others remain chilly despite the furnace running, it indicates an uneven gas flow. This inconsistency can stem from a gas valve struggling to open or close fully, disrupting heat distribution.

2) No Heat Production

Perhaps the most apparent sign of a gas valve problem is a lack of heat production. If your furnace is running, but you're not feeling the warmth you expect, the gas valve might not be opening to allow the gas to reach the burner. This situation requires immediate attention, as prolonged exposure to cold temperatures can lead to discomfort and health issues.

3) Pilot Light Issues

Older furnace models often have a pilot light that needs to stay lit for the gas valve to function correctly. If you find that the pilot light frequently goes out, it could be a sign of a faulty gas valve.

A malfunctioning valve might not supply a consistent flow of gas to keep the pilot light burning, causing it to extinguish regularly.

4) Strange Noises

Unusual noises from your furnace, such as hissing or whistling, can indicate a gas valve problem. These noises occur when gas escapes through a partially open valve, creating a hissing sound. Any unusual sound should be investigated promptly, as it might signify a gas leak, which poses a severe safety hazard.

5) Gas Smells

A distinct rotten egg odor, similar to the smell of natural gas, is added to the gas supply to help detect leaks. If you notice this smell near your furnace, it could indicate a gas leak caused by a faulty gas valve.

Gas leaks are dangerous and require action. Evacuate your home, leave the door open, and contact the gas company and emergency services from a safe location.

A sudden increase in your gas bills without a corresponding increase in usage can be a subtle indicator of a gas valve problem. When the gas valve doesn't close completely, even when the furnace is not running, it leads to a continuous gas flow. This continuous flow results in higher gas consumption and inflated bills. Monitoring your gas bills regularly can help you identify such issues promptly.

6) Short Cycling

Short cycling refers to a situation where the furnace turns on and off, running for short periods before shutting down. A faulty gas valve can cause short cycling, disrupting the heating cycle. This rapid on-and-off pattern strains the furnace and hampers its efficiency, leading to inconsistent heating and potential damage to the system.

If you find it increasingly challenging to start your furnace, the gas valve might be at fault. Difficulty in igniting the burner could indicate a gas flow issue due to a faulty valve. Ignoring this problem can be frustrating, especially during colder months when a functional heating system is paramount.

What are the Three Basic Designs of Check Valves?

Check valves are essential components in various systems, ensuring the flow of fluids or gases in one direction only. These valves prevent backflow, safeguarding pipelines, pumps, and other mechanical systems.

Understanding the basic designs of check valves is crucial for selecting the right one for specific applications. In this brief guide, we'll explore three fundamental designs of check valves.

1. Swing Check Valves

Design: Swing check valves feature a hinged disc, a flap, that swings open when fluid or gas flows in the desired direction. When the flow stops or reverses, the flap swings back into a closed position, preventing backflow.

Application: Commonly used in horizontal pipelines where backflow prevention is necessary, swing check valves are effective for applications with moderate flow rates.

Advantages: Swing check valves offer minimal resistance to flow, making them suitable for systems with low-pressure drops.

2. Lift Check Valves

Design: Lift check valves consist of a disc or piston-like element that lifts away from the seat when forward flow occurs. When the flow reverses, the disc or piston settles onto the seat, blocking backflow.

Application: Lift check valves are versatile and find applications in vertical or horizontal pipelines, offering effective backflow prevention in various systems.

Advantages: Lift check valves provide a tight seal, minimizing leakage. They are suitable for high-pressure systems and applications with variable flow rates.

3. Ball Check Valves

Design: Ball check valves feature a spherical ball inside the valve body, which moves away from the seat to allow forward flow. When the flow stops or reverses, the ball settles onto the seat, preventing backflow.

Application: Ideal for applications with low flow rates and limited space, ball check valves are commonly used in household appliances, pneumatic systems, and small-scale plumbing.

Advantages: Ball check valves offer quick response to changes in flow direction, making them suitable for systems where rapid opening and closing are necessary. They provide minimal resistance to flow, enhancing efficiency.


Your furnace's gas valve might be small, but its role in keeping your home warm and safe is immense. Regularly checking it with a multimeter might seem like a minor task, but it's crucial to maintaining your furnace's efficiency and your family's safety. 

We hope you know “how to check furnace gas valve with multimeter?” By understanding its importance, following the steps, and observing safety precautions, you can ensure your furnace operates smoothly, providing the warmth and comfort your home deserves. Stay warm, stay safe!