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DUST, HVAC CONTAMINATION STUDY
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INSPECTION CHECKLIST - OUTDOOR UNIT
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LEED GREEN BUILDING CERTIFICATION
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MOLD in AIR HANDLERS & DUCT WORK
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REPAIR GUIDE, AIR CONDITIONERS / HEAT PUMPS
REPAIR & DIAGNOSTIC FAQs for A/C
THERMOSTATS, HEATING / COOLING
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WATER COOLED AIR CONDITIONERS
WINDOW / WALL AIR CONDITIONERS
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Refrigerant filter drier canisters: this article discusses when, where, how and why refrigerant driers are installed on refrigeration, air conditioning and cooling systems. Our photo at page top shows the typical location of a refrigerant dryer canister at the compressor/condenser component of a split system air conditioning system.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
A typical indoor refrigerant filter/drier location is shown in our sketch at left: see the blue canister with red arrow showing refrigerant direction flow in Carrier's sketch at left (edited)).
Watch out: UNIT DAMAGE HAZARD Failure to follow this caution may result in equipment damage or improper operation. Installation of filter drier in liquid line is required.
- Source: Carrier
Below our photo illustrates the installation of a refrigerant filter/drier at the A-coil - you can see the horizontal drier canister to the right of (and protecting) the tan-colored Thermostatic Expansion Valve (TEV).
Source: PURONR (R--410A) REFRIGERANT QUICK REFERENCE GUIDE-
Watch out: be sure to check the installation instructions for your specific HVAC equipment before installing a filter-drier. And be sure that you are installing the proper type of filter-drier, intended for use on a suction line or on a liquid refrigerant line. For example, some newer equipment such as the 24 ANA Infinity™ Series Air Conditioners with Puron® Refrigerant, include instructions that state:
Compressor Burnout Filter Driers: Why is a filter-dryer critical on an air conditioner or refrigeration system that has been worked-on?
Water anywhere inside the refrigerant handling system (tubing, compressor, condenser, or refrigerant metering cap tube or thermostatic expansion valve) freezes, making the system inoperative. The inside of any refrigeration system must be pure refrigerant: no air, no dirt, no water, and no mix of various refrigerant gases other than a single gas for which the system is designed.
Watch out: above we mentioned that on a badly contaminated refrigeration system the technician may install a new or a second drier a few months after the original repair/service. If a drier has become saturated in the course of doing its job (of removing moisture from the refrigerant system), it begins to restrict the flow of refrigerant through the system. This refrigerant flow restriction will cause pressure changes indicated by a temperature difference on either side of the drier - that's one way you could quickly test for a clogged refrigerant drier.
Watch out: if you change the size of the drier that you have installed on a refrigeration system that does not use a refrigerant receiver (as is the case with most residential appliances and air conditioners/heat pumps, you will have to compensate in the charge used in the system (if it is a "critically-charged" or precise charge system as we've discussed here). For example if you install a larger drier than was previously in place you'd need more refrigerant charge in order to assure that the frost line will still extend to the end of the evaporator.
Special Burnout Filters Used after a Compressor Motor Replacement
A "burnout drier" is a special drier installed on refrigeration systems when a compressor motor has burned out and the compressor is changed out. In this case we have to clean the acid and lacquer out of the refrigeration system. (Using Karene-R11).
The system is washed out and then the burnout drier is put in temporarily in the low side or return refrigerant line, replaced one or more times as needed, until the system is cleaned. Therefore you might not normally see a drier in this position on a system except during that repair process.
More details about what moisture and contaminants do to a refrigeration system are discussed at REFRIGERANT LEAK DETECTION
What is the Life Expectancy of a Refrigerant Filter Drier Installed on an Air Conditioner or Heat Pump or Refrigerator/Freezer?
Ordinarily a drier should last the life of the equipment, given no leaks or problems with the system that require that the refrigerant piping be cut. (The piping will be cut and the system opened, for example, if a cooling coil or condensing coil has to be replaced.)
Watch out: some filter driers installed on refrigerant piping have special short-term intended uses such as during new equipment installation or when used as a compressor burnout filter drier. E.g. Carrier's new equipment installation instructions state
Frequently Asked Questions (FAQs) about refrigerant Filter-Driers
Question / Comment: Failure to install a burnout filter/dryer may have led to early failure of the replacement unit
After a contractor replaced a failed compressor ) that failed via acid burnout) he left in the 16 year old suction line filer,,,he never put in a burnout filter at all....the compressor failed in just 13 months they normally last 18 plus years. I think he should refund the 42,000 he charged me what do you think.
Tom, we agree with you. Good practice would have been to install a burnout dryer-filter on the system and perhaps, depending on how dirty the system was from the first burnout, to return and swap in a second filter unit after a period of time. The cost to the tech to come back to make that second change is not trivial however, and both owner and tech are tempted to skip it. The risk is clogging of the thermal expansion valve or other parts in the future, leading to still more repairs.
But I wouldn't assume that the prime or only cause of failure of the replacement compressor was just due to the dryer omission. A tech who doesn't know about the importance of all of the steps in replacing a burned out A/C or heat pump compressor may not have known other important steps to take.
Question: Where does the refrigerant drier/filter go?
Doug we see filter dryers installed at both sides of the compressor. It depends ... if a system is thought to be contaminated there are advantages of having a filter at both ends of the compressor motor, and it certainly doesn't hurt.
Questions & answers or comments about the need for and installation of filter drier canisters on air conditioners & heat pumps.
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