To keep dirt and dust at a minimum, and to ensure the longevity of your system, it’s important to replace the filter-drier installed in your heat pump after motor burnout. Each step of the procedure needs attention and as the homeowner, you need to know all the steps. Today we’ll be looking at the most important steps.


Applying filter-driers properly in your heat pump

By properly applying new filter-driers to your heat pump, you will protect the air conditioning unit as well as your air ducts from dirt and mold contamination which would otherwise result in extensive air duct cleaning. There are two main ways in which filter-driers can be applied to the heat pump of your AC system. Let’s have a look at the two.


First Application – Two Standard Driers

HVAC system manufacturers will often use two standard driers rather than a bi-flow drier. With this, they can keep the costs low, introduce fewer working parts into the drier system, and have better moisture absorption. Often, they provide just as much protection, if not more, than a reversible filter-drier.

Here, the set of standard driers are installed very close to the expansion valves. Also, one of the driers are installed in the outdoor section, and the other drier is installed in the indoor section of the heat pump. It’s not uncommon to install both driers in the outdoor section of the heat pump, as it is easier to perform maintenance and repairs. Here, one is set next to the expansion valve and the other near the check valve. As standard filter-driers do not support bi-directional flow, these configurations ensure that the flow maintains a single direction. With a reverse flow, you will end up washing out the dirt which has already been filtered and ends up causing a pressure drop as well.

When servicing units and installing filter driers out on the field, it’s better to directly install the drier ahead of the expansion valve, in either the outdoor or indoor sections of the heat pump.


Second Application – The Reversible Filter-Drier

The best heat pumps, such as the ones from Goodman come with bi-flow or reversible filter driers, which allow flow in both directions. Although a reversible filter-drier is usually installed in the reversing liquid line that runs between the indoor and outdoor sections of the heat pump, it does not add protection to the system and might result in excessive pressure drops, which hurt the capabilities of the machine. Therefore, after motor burnout, a reversible filter-drier should only be used once the older filter-driers have been properly removed.


What to do after a burnout

1.       Check the severity of the burnout by taking an acid test from the burnt-out compressor.

2.       You can install the new drier before or after the accumulator but ensure that it is between the four-way valve and the compressor.

3.       If contaminants still remain after the initial cleaning procedure, the filter-drier should be installed between the accumulator and the compressor, however, this area usually has other parts which make the installation difficult. In this case, re-pipe the suction line drier to allow installation of the drier outside the cabinet of the heat pump.


Cleaning-Up After a burnout

1.       Either choose the same size drier or oversized drier in the liquid line ahead of each expansion device and drier. If your unit contains two liquid line driers, both of them need to be changed.

2.       Experts recommend installing a drier, much larger than the original, in the common liquid line and the common suction line. In this case, run the unit for a single day in an operation mode, and then replace the liquid line drier with a reversible filter-drier.


See the summary here – Two Standard Driers vs. Reversible Filter-Drier for Heat Pumps [Infographic]

Two Standard Driers vs. Reversible Filter-Drier for Heat Pumps


The process of replacing the filter driers after a motor burnout is a bit complicated, therefore as an aware customer it’s important for you to understand how things work to ensure that you get the best AC repair and maintenance services to keep your HVAC system healthy throughout its lifetime.


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