How to Use a Fin Comb

Fan Coil Unit close-up of fins on air conditioner
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HVAC units are expensive. This is because they do a big job, and if regularly maintained, they will do that big job for years on end. Another reason for their hefty price tag is the fact that they're made up of multiple components that can be swapped out and individually maintained to ensure the longevity of the overall unit.

One of the many components of an HVAC unit that is designed to be maintained is the condenser coil. The condenser coil is made up of copper tubing surrounded by thin metal fins. These fins can easily get bent and obstructed, restricting airflow and causing an unnecessary load to be placed on the unit. This can result in increased energy usage, poor performance, and even premature failure of the unit. To straighten these fins, all it takes is a tool called a fin comb.

What Is a Fin Comb?

A fin comb, also known as a coil fin tool, is a specialty tool used to straighten the bent fins of a condensing unit for an air conditioning or heat pump system. You will find the aluminum coil fins on central air conditioning system condensing units or window air conditioner condensing units. The aluminum fins are made of delicate thin gauge metal and can get damaged by tree limbs or sticks, hail, high-pressure power washing, and other factors.

Fin Comb vs. Fin Brush

Fin Comb
  • Stiff comb on end

  • Used for straightening bent fins

  • Multiple specific sizes

Fin Brush
  • Soft brush on end

  • Use for cleaning fins

  • No specific sizes

Parts of a Fin Comb

There is no standard design of a fin comb, but most feature a handle with a comb on the end. Some fin combs feature multiple combs that can be spun or otherwise shifted into place in order to accommodate multiple fin sizes. Fins are measured in FPI (fins per inch), so figuring out what size you need is as simple as measuring and counting how many fins there are in an inch.

As stated earlier, there are multiple different types of fin combs. Some feature a small handle that is intended for quick use and easy storage, others feature long ergonomic handles that are intended for long use and comfort. Beyond choosing the right FPI for your comb, there is no right or wrong tool to buy. Simply compare options and figure out which is best for your needs.

What Part to Use

There are not any swappable components on a fin comb, beyond the multiple sizes of combs. To know which comb to use, measure your FPI and use the corresponding comb.

How to Use a Fin Comb

  1. Clean Coils

    Before reaching for your fin comb, clean off your coils. Use a shop vac to remove any loose debris. Follow this up with a no-rinse foaming coil cleaner.


    Some styles of radiators can also be cleaned with a fin comb. However, radiators with segmented fins will be difficult to clean with this tool.

  2. Measure Fins

    Use a tape measure to figure out your coil's FPI. Place the tape measure against the coil perpendicular to the fins and count how many fins fit within an inch of space.

  3. Straighten Fins With Fin Comb

    Choose your comb size according to your measurement. Starting at the top, firmly grasp the comb and pull it downward through the bent fins. The shape of the fin comb will evenly space the fins and bend them back into their original form. You may need to make multiple passes on severely bent fins.


    Damaged fins can be incredibly sharp. When using a fin tool, wear protective gloves and be careful not to let the edge of the bent fins touch exposed skin.

Buying vs. Renting

A quality fin comb is an inexpensive tool that should be used on a regular basis in order to keep your HVAC unit running at peak performance. For this reason, we recommend buying this tool rather than renting it.

Keeping a Fin Comb in Good Condition

The only way to ensure your fin comb lasts as long as possible and stays in good condition is to use the proper size comb for your fins. The combs, especially those made of plastic, will wear with use, requiring you to purchase a new fin comb once that time comes.

When to Replace Your Fin Comb

Once the combs on your fin comb wear out or lose their pointed ends, it's time to replace your fin comb. Additionally, if you move or purchase a new HVAC unit with a different FPI, you will need to replace your existing fin comb to accommodate the fins on the new system.