Proper Liquid Line Drier Location

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Diagram above by Carrier 

It’s really easy to put a liquid line drier in the proper location, it’s still more common that it gets installed in the WRONG location , namely, right at the condensing unit (OK it isn’t that big of a deal but for dramatic emphasis). Installing at the indoor coil is good practice for two main reasons.

#1 – It better protects the metering device (expansion valve or piston) from anything that may be in the liquid between the outside and the inside

No matter what, when you first put a unit in Service, you are either releasing the charge on the liquid line first or adding pressure in the liquid line. This means if anything is in the liquid line it is going to hit the indoor metering device first and putting the drier inside better protects the valve.

#2 – It won’t turn into a rusty mess and start leaking after a few years

This is pretty simple, so to make this tech tip a bit more in depth here are some other drier best practices.

  • Don’t “sweat” out an old drier. When you heat an old drier the moisture it has previously absorbed is driven out of the drier and back into the system. Cut it out instead.
  • Use the right type and size. Different driers have different purposes and vary in capacity. If you have a heat pump make sure to use a “bi-flow” drier. If you are mitigating a burnout ensure you are using a burnout suction drier. Make sure the capacity of the direr matches the capacity of the system, this will take a bit of reading. However for residential systems you can use 8 cu/in on small tonnage systems only. To be safe I would generally stick with 16 cu/in liquid line driers (chart by Parker / Sporlan)

  • Don’t burn the paint on a drier when installing. Not only will it look ugly, it will be more prone to corrosion. Use a damp cloth or other heat control methods.
  • Point the arrow in the correct direction. Suction driers point towards the compressor and away from the evaporator. Liquid line driers point toward the metering device and away from the condenser.
  • A liquid line drier goe in the liquid line NOT in the discharge line. The discharge line is between the compressor and the condenser. The liquid line is between the condenser and the metering device.
  • Flow nitrogen while brazing and pull a proper vacuum. Both of these practices are more important than whether a drier is inside or outside.
  • Remove all old line driers and install a new line drier whenever the system has been open and exposed to the atmosphere. Sometimes the old ones were in the wrong place, if so, go ahead and straight pipe them and install your new filter / drier in the proper location.

— Bryan



  1. Avatar Jonathan Smith "Freonjon1" says:

    1. Many condensers come with a dryer installed. Never stack dryers. This add too much restriction to a system.
    2. The only issue with installing a liquid line dryer at the evaporator is a tech not verifying that that dryer is removed when a new dryer is installed.
    3. Suction line dryers are typically designed to be installed and after the clean up removed because the pressure drop and trash recirculating throughout the system. If your plan is not to cut out the suction line dryer and install a pipe in place of the dryer, then install 2 in line ball valves, one before and one after the dryer and install a cartridge/core type dryer shell so the dryer core can be replaced or removed after the cleanup process is complete. Remember that the dryer shell must be evacuated each and every time it is opened whether a new dryer core is installed or not.

  2. Avatar Gary L Reecher says:

    Putting the drier inside above the evaporator liquid line and the drier outlet straight down any bubbles in the refrigerant will not be forced into the metering device.

  3. Avatar Bill says:

    I’ve seen a bunch of liquid driers on mini splits…..

  4. Avatar Bill Michael says:

    This is probably a dumb question but I am a student and I am still not clear about where to put the drier/filter BECAUSE I thought that in a heat pump the condenser and the evaporator swap places. (Thus the terms: “Indoor Coil/Outdoor Coil”). Can you please clarify to me that the liquid line drier must or should go right before the Indoor Coil?

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