How Much Does It Cost to Replace the Heat Exchanger of a Furnace?

If you use a furnace to heat your home, you know the unease that occurs if it suddenly stops working. Furnaces may stop heating, cycle on and off rapidly, begin blowing cold air, or suddenly start costing more to run without an increase in warmth. All these problems are fairly common, especially since many furnaces today are designed to last 10 or more years. But during this time, many things may break or wear out.

The national average cost of furnace repair is between $250 and $1,500, with most people paying around $425 for a gas furnace repair replacing the ignitor and flame sensor.

Furnace Repair Costs

Furnace Repair Service Fee Cost

Many causes of furnace failure have nothing to do with the furnace itself. This includes a tripped circuit or too much clutter around the furnace, causing a sensor to misfire. When you call an HVAC technician to examine your furnace, be prepared to pay a service call fee of between $75 and $250 for the technician’s time. This fee applies even if they do not perform any repair work, such as cleaning a dirty sensor or resetting a sensor or circuit breaker.

If the technician arrives and finds your furnace needs repair, the service fee is usually waived, and you only pay for the repair and labor.

Furnace Repair Cost Per Hour

For many repairs, your technician charges an hourly rate to make the repair or to replace a faulty or worn part. This fee varies by technician and company, but most charge between $75 and $200 an hour. Some complex repairs have higher hourly costs than simple repairs, but most companies state their hourly rate upfront.

Furnace Repair Costs by Problem

Sometimes the issue seems vague, and the cost to repair the furnace may be linked to what the problem is. Many common repairs are identifiable by sight, smell, or sound.

Furnace Leaking Water Repair Costs

If your furnace is leaking water, it is most likely caused by one of two things. The first is for high-efficiency furnaces only. High-efficiency furnaces condense exhaust to extract more heat, and that condensation needs to drain. A clog in this line may cause your furnace to leak. This repair is quick and costs around $75.

If your furnace is leaking something that looks like water but has a strong odor, your heat exchanger has likely cracked. This has a wider range of costs because it means taking your furnace apart to reach it, then replacing it. This costs $800 to $1,500 to fix.

Furnace Scraping Sound Repair Costs

If your furnace is making a loud scraping noise, it is likely caused by some worn-out ball bearings. It needs to be dealt with right away, or you may have bigger problems and more expensive repairs. The cost to replace the ball bearings is between $100 and $250.

Furnace Squealing Sound Repair Costs

If your furnace is making a loud squealing sound, there is a loose, slipping, or damaged belt on a motor. It is a simple repair and costs between $150 and $250 on average.

Furnace Loss of Heat Repair Cost

If your furnace is turning on but not getting hot, this may be caused by several issues, from a faulty blower motor to a furnace ignitor. In some cases, it could be a circuit board malfunction. The cost to clean your burner and gas valve is around $150 to $400; repairing an ignitor is $300 to $425; an HVAC circuit board repair cost is $250 - $600; and repairing a faulty motor costs up to $1,500, depending on the motor type.

Furnace Cycling On and Off Frequently Repair Cost

If your furnace keeps turning on and off more frequently than it should, you are looking at a circuit board repair cost of $250 - $600 in most cases, although this may also be a dirt flame sensor. You should also check your filter because a dirty filter may cause this. If you remove the filter and it functions normally, install a new one.

Furnace Blowing Cold Air Repair Cost

A furnace that is blowing fine but the air coming out is cold is most likely having an issue with the circuit board. A repair cost of $250 - $600 is the most common. Sometimes, a dirty flame sensor may also be the issue.

Furnace Strong Gas Smell Repair Cost

If there is a strong gas smell around your furnace, it is probably the gas line. A furnace gas line leak repair cost is between $500 and $750 on average. If you smell gas, leave the house immediately and call for emergency service right away because this is extremely dangerous.

Cost to Replace Parts of a Furnace

In most instances, if you have a problem with your furnace that cleaning or a minor repair does not solve, you need to replace one or more parts to fix the problem. The exact replacement cost for each part is derived from several factors, including the furnace manufacturer, how difficult the area is to reach, and the technician’s hourly cost.

Cost to Replace a Furnace Transformer

Furnace transformers are one of the lowest cost repairs, although they are less common than others. If your transformer has gone and needs replacing, it costs $100 - $175 on average.

Cost to Replace a Thermocouple on a Furnace

Thermocouples are also relatively inexpensive to replace. They have an average cost of $100 to $250, mostly depending on the furnace brand and how hard it is to reach.

Cost to Replace a Pressure Switch on a Furnace

Your pressure switch or relay switch sometimes fails or becomes stuck and needs a replacement for your furnace to turn on and off correctly. This costs $150 - $300.

Furnace Valve Replacement Cost

The gas valve on your furnace may corrode or clog over time, depending on its age and maintenance. If this happens, replace it for a cost of $200 - $1,000, depending on its location on the line and how easy it is to access.

Furnace Circuit Board Replacement Costs

Your circuit board controls everything on the furnace, and if it becomes faulty, any number of things may go wrong. Identifying that it is the circuit board and not something else is often the biggest challenge in this replacement. Costs range between $250 - $600.

Ignitor and Flame Sensor Replacement Cost

If your flame sensor or ignitor is the issue, you will likely have to replace both at the same time. This has a cost of $300 - $425.

Furnace Flue Pipe Replacement Cost

Your furnace needs to vent exhaust outside as part of its combustion. Newer, more efficient furnaces often use PVC exhausts that are less likely to be a problem or need replacement. If you have an older, less efficient furnace, your flue pipe replacement costs are around $400 - $800.

Blower Motor/furnace Fan Replacement Cost

A blower motor failure is an indication that your furnace is reaching the end of its lifespan. You may replace it, which has a wide range of costs, $400 - $1,400, due to the many sizes. However, when this stops working, many people choose to replace the furnace instead of repairing it.

Draft Inducer Motor Replacement Cost

Your draft inducer is what pulls the combustion gasses through the heat exchanger. It is less likely to need repair, but if it stops working, expect replacement costs between $500 and $700.

Heat Exchanger Replacement Cost

If you suspect your heat exchanger is cracked, replace this immediately because it causes carbon monoxide gas to build up in your home. Heat exchangers cost $800 to $1,500 to replace, mostly because they are so difficult to reach inside the furnace.

Emergency Furnace Repair Costs

If your furnace stops working suddenly in the middle of the night or on a cold winter’s day, your HVAC technician may charge you an emergency repair cost to come out quickly. This varies by technician, and while this is an emergency for you, sometimes callers ahead of you may push your service out until the morning hours. If this happens, your visit may end up being cheaper despite when you made the call. Expect an emergency visit to have a flat fee of $75 to $250 just for entering the door. This is not waived when making repairs like it normally is for a service call.

Signs Your Furnace Needs Repairs

Most of the time, your first indication that your furnace needs repair is when it stops working. However, for some furnaces, there are other signs. These include scraping and squealing noises, leaking water, a bad smell, higher than average electric bills, or people in your household showing carbon monoxide poisoning signs, such as headaches, nausea, and flu-like symptoms.

If you experience any of these issues, it is best to call your HVAC technician right away.

Furnace Repair vs Replacement

If your furnace is older, you may wonder whether it is worth the repair or if you should replace it. Most HVAC technicians use this rule of thumb - take the age of your furnace and multiply it times the cost of the repair. If the figure is higher than $5,000 - the starting point for new furnaces - then you are better off replacing. If the number is lower than $5,000, make the repair.

For example, replacing the ignitor on a 3-year-old furnace equals $900 - $1,275 - make this repair.

If you need a new heat exchanger on a 9-year-old furnace, this would equal - $7,200 - $13,500 - get a new furnace.

Thermostat Replacement Cost

Many times when your furnace stops operating or begins to operate erratically, the furnace may not be the problem. Instead, it could be a faulty thermostat. Replacing your thermostat costs $145 - $230 and solves many of your furnace issues.

Furnace Servicing Costs

Regular maintenance and service prevent many furnace repair costs. Service and maintenance include oiling belts, inspecting for wear, cleaning sensors and burners, and changing filters. For the best results, have service performed yearly. This has a starting cost of around $70. But for furnaces requiring more cleaning or that may have higher furnace cleaning costs like oil furnaces, your service fees may be closer to $200.

Additional Considerations and Cost

Changing your filters regularly keeps your furnace running better for longer. A clogged filter may cause your furnace to stop working. Filters cost between $10 and $40 a piece, depending on what you want to filter out. Pet hair and allergen filters cost more than standard filters. For best results, change your filter every 1 - 3 months as recommended by your furnace manufacturer or whenever you no longer see light through them.