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by Rifat A. in Blog 0 comment

Moisture is the biggest enemy when it comes to effective and efficient refrigeration. In the case of heat pumps, your unit will only be able to stand only a tiny amount of water before stopping all operations. In addition to the moisture, the air to be conditioned needs to be properly filtered to remove dust and dirt. This is why, your heat pump will always need factory-installed or field-assembled driers, depending on the need.

So, what are the different types of driers?

  1. Liquid Line Driers
  2. Suction Line Driers


Understanding the Difference Between Filter Driers in Heat Pumps

The liquid line filter drier is often factory-installed and is installed near the expansion valve of the refrigeration unit. On the other hand, the suction line drier is often used after repair work is done after a motor blowout. This way, once the repair work is done, the compressor is not damaged from unfiltered air, newly introduced into the system.

The filter driers used in heat pumps are usually reversible as refrigerants in Heat Pump applications need to flow both ways. This in turn complicates the design of the filter drier itself to ensure that no contaminants pass either way within the drier.

With the right filter-driers in place, the lifetime of your HVAC system as a whole is improved, as you do not have to worry about internal component damage to the heat pump, and your air ducts will receive cleaner air, with less moisture. This in turn prevents the accumulation of dirt and mold growth, which requires expensive air duct cleaning to remove.

1.      Liquid Line Driers

Liquid line driers have been the first choice in refrigeration units for many years and companies have made it a point to ensure that excess moisture is quickly eliminated. If the condensate or moisture generated in the heating and air conditioning process is left as it is, it could quickly stagnate and lead to the formation of sludge, accelerate corrosion, and create a breeding ground for mold. Once this mold hits your air ducts, you will need thorough air duct cleaning to get rid of it.

In addition to the mold and sludge problem, moisture in a refrigeration system is known to cause the expansion valve to freeze-up, and compression motor burnout. Moreover, if the water is not properly drained away, mechanical functions start to get inhibited. Over the years, however, as HVAC systems have become more complex, driers have become responsible for a few more things.

Types of liquid-line driers

There are generally two main types of liquid-line driers. One is the straight-through sealed type and the angle replaceable core type. Both types offer protection in heating and cooling cycles and use the singular filter drier. They have internal valve checks which offer a bi-directional flow of refrigeration and filtration. Because of this, the traditional external valve checks normally used in heat pumps are now removed. Therefore, the complexity of the system is reduced, and cost-effective moisture and debris removal are possible.

Most modern liquid driers are designed for:

  1. Effective moisture removal
  2. Dirt and dust filtering
  3. Stagnant acid removal

Manufacturers often equip their heat pumps with the best in-line filter driers. As seen in Goodman heat pumps and Trane systems.


2.      Suction Line Driers

There isn’t much to say about suction line driers as they are mostly used after motor burnout, rather than during the initial construction of the heat pump itself. Suction line filter driers work by extracting all the dirt and dust particles out of the air and prevents it from entering the compressor, where it might damage the sensitive parts. It’s important to ensure that the suction line filter drier is installed as close to the compressor as possible so that, even after under poor circumstances, any air entering the compressor will have been filtered out properly.



That’s all there is to know about the filter-driers used in heat pumps. Be sure to consult your favorite HVAC AC maintenance & repair specialists should you face any troubles with your heat pump or driers.


See the summary of this content here in the infographic – Heat Pump Filter Drier Types [Infographic]

Heat Pump Filter Drier Types
Heat Pump Filter Drier Types

By the way, are you looking for an HVAC system for your home?

Check out Green Leaf Air Store where we have a wide range of residential & commercial HVAC system including: –

Complete Goodman HVAC SystemHeat PumpsTrane HVAC systemAir HandlersGas Furnaces

Besides, for any AC installation, AC replacement and AC repair services, call Green Leaf Air to ensure you get the best quotes and satisfying service.

Rifat A.

HVAC Expert, Author & Mathematician... rifatahmed.com

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