The national average cost to replace a furnace gas valve is about $415 for a single-stage furnace.
Two-stage and variable capacity gas valve replacement can be as high as $850, but are usually closer to $500. These are the cost of gas valve replacement when you hire a furnace repair technician for the work.
Gas Valve Replacement Cost Overview
How much does it cost to replace a furnace gas valve? Let’s break it down.
Parts Cost: Replacement gas valves cost from $65 to $300 or more for the part. Cost depends on gas line size, gas valve stages, 1, 2 or variable, and the manufacturer. A quick inventory reveals a cheap Rheem/universal 1-stage gas valve for below $60, an Amana/Goodman single-stage valve for about $150, Carrier unit for $250 and a Lennox 2-stage gas valve for $300. A Trane modulating gas valve goes for a little more than $300.
Labor Cost: Labor for 1.5 to 3 hours of work will run $150 to $400 or more depending on who you hire, where you live and how complex the job is.
Summary: DIY cost for the part and gas tape runs $70 to about $325 for most furnaces. Hire a pro, and your bill rises to $225 to $700.
Gas Valve Failure
One of the most common issues that come up with any furnace problems is that the gas valve will fail. You can clean the valve to try to remedy the problem, and that will buy you time. Remove the valve, and gently clean it with Emery cloth. If the hole is visibly clogged, do what you can to remove the buildup.
While you’re in there, consider cleaning the burners too using this Pick HVAC how-to guide.
Eventually, the valve will need to be replaced, and you might find it time-saving and cost-effective to simply replace the gas valve than clean it.
Cost Factors to Replace a Furnace Gas Valve
Is it under warranty? Before you decide to hire an HVAC technician to check your furnace and see if your gas valve needs to be replaced, check the warranty on your furnace. Most furnaces have a 10-year parts warranty. The warranty will cover the replacement cost of the part, but it does not cover labor.
There are many factors that will contribute to the overall cost to replace the gas valve for your furnace. First, whether you have a single or a two-stage or variable-capacity furnace. Two-stage and modulating furnaces require a more expensive valve.
The gas line size also is a cost factor. A gas valve for a furnace line that is ¾” is more expensive than furnace valves for ½” gas lines.
Propane vs Natural Gas (LP or NG)
Most furnaces either use natural gas or propane as fuel for the furnace. Gas valves generally will be set up or come standard for natural gas, so if you need to convert the valve to propane you can expect to pay around $35 for the conversion kit.
There are very few things that you might need to purchase in addition to the part. Some gas valves require a wiring harness. The wiring harness is usually included with the gas valve, but you may have to purchase it separately for between $10 and $30. We recommend replacing the wiring, since the part is cheap and takes just a few minutes for you or a furnace technician to install.
You’ll need to wrap Teflon tape, aka yellow tape and PTFE tape, around the threads of the fitting to secure the connection against leaks.
Read on for more information about gas valves.
What Causes Furnace Gas Valve Failure?
Not only do you most likely want to know if your furnace gas valve is not functioning properly, you will also want to know what caused it to actually fail. There are few possible reasons why gas valves often fail. Over many years, gas valves will simply wear out and need to be replaced. Also, if the valve happens to be submerged or have any water seepage, this can cause the valve to fail.
Electrical issues can also be the issue. The components that make up the gas ignition system or if there is a short in the safety circuit will make the valve not work properly. Finally, the thermocouple, also called the flame sensor, may need to be replaced or at least cleaned or replaced. Both cleaning and replacing are DIY jobs.
Furnace Gas Valve Troubleshooting
How do I know if my furnace gas valve is bad? That’s a common question.
Troubleshooting a furnace that won’t start involves checking the gas valve. One sure sign that the valve needs replacing is that it shuts down, and the burner goes out, before your thermostat is satisfied. The valve is either stuck or not working properly.
Another way to check your gas valve to see if it is leaking when it should be closed is to coat the area around the valve with soapy water. If there is any sort of leak at all, the escaping gas will cause the water to bubble up, and you will be able to see it very clearly. This will show that your valve is faulty and needs to be replaced. Finally, if your furnace burners are sputtering or making other unusual noises, or if the burners run for a long time without warming your home, then you should contact a licensed HVAC technician to determine if the problem is the gas valve or if there are other problems with your furnace.
DIY or Hire a Professional?
Replacing a furnace gas valve is something that a homeowner can accomplish on their own by following the directions carefully. YouTube has many videos available to walk you through the process including the necessary safety steps of shutting off power and the gas supply before disconnecting the gas line to the valve.
Anytime you are working with gas or electricity, you run the risk of possible issues that may arise. Unless you are very familiar with working with gas and/or furnace systems, it is recommended that you hire a professional HVAC technician to replace the gas valve. It will most likely take less than a few hours to complete, and you will have the peace of mind that the job is done correctly the first time.