Repairs & Safety Methods for Type 2 HVAC Equipment
- SkillCat Team
- Sep 16
- 6 min read
EPA 608 Type 2 Chapter 5
Diagnosing Issues
In this module, we will take a look at maintenance guidelines and some common issues we have to deal with when servicing small appliances.
Recovery Device Maintenance
Practicing technicians need to regularly check recovery equipment for refrigerant leaks. The earlier we can catch a leak, the easier it is to repair the recovery equipment.
We don’t want to find out mid-recovery that the recovery device is leaking. A leaking recovery device will vent refrigerants into the atmosphere and can also lead to dangerous scenarios with flammable or toxic refrigerant.
To prevent these issues, we as technicians should regularly check our recovery devices for leaks.
Leak Repair
For small appliances that are leaking, the EPA does not technically require us to repair the leak. But the EPA recommends to repair it whenever possible.
Financially, it also makes sense for us to repair any leaks we find. Repairing leaks would prolong the life of the equipment and smaller leaks are always easier to fix than big ones.
The requirements for small appliances are not as stringent because the amount of refrigerant is under 5 lbs, by definition. And refrigerants used in household refrigerators, especially new ones, are generally non-toxic.
For example, newer household refrigerators contain about â…“ lb of hydrocarbon refrigerants, which are non-toxic. This is compared to 50+ lbs of refrigerant in other appliances.
Additionally, if the appliance is still working properly, that means any leak in the appliance is minimal. But if the appliance is not working and we find that the system pressure is 0 psig, this means that there was likely a leak in the system and there is no refrigerant left to recover.
Compressor Burnout
A compressor burnout is when the motor of the compressor fails catastrophically. For a sealed system, pungent smell usually indicates compressor burnout.
When a compressor burns out, it produces a highly acidic oil. Most of this oil will remain in the compressor, but some oil will make it to the plumbing and other components of the system.
In the event of a suspected compressor burnout, we should first recover any refrigerant in the system in a separate recovery container. It might be contaminated so we don’t want to use a recovery container used for other refrigerants.
Then, look for signs of contamination in the oil.
Signs of contamination are:
Discolored oil, and
An acidic smell
If we see these signs of contamination, the system needs to be flushed because oil can be present in other components in the system. Flushing the system will clean any contaminants from other components of the system.
Non-Condensables
Non-condensables are gases that do not condense (or turn from vapor to liquid) at the operating temperatures of the system. Examples of non-condensables are water vapor and nitrogen.
The presence of non-condensables in the refrigerant changes the properties of the refrigerant. It makes the system less efficient at cooling and increases the pressure of the system.
If there is a high quantity of non-condensables in the system, this shows up as increased pressure on the high side of an active recovery device. So if you see an abnormally high pressure on the high side of an active recovery device, we know that there is a lot of non-condensables in the refrigerant.
Taking pressure readings allows us to determine whether there are non-condensables present. We can check what the refrigerant’s pressure should be at a given temperature by looking at the refrigerant’s PT chart. If the pressure reading is off by a lot, then we know there are non-condensables present.
To remove non-condensables, we can use:
Filter driers. Filter driers are components that use desiccants to trap contaminants, including: acids, wax, and moisture.
We can also flush the system to get rid of non-condensables.
Safety
In this module, we will learn about a few safety practices that need to be kept in mind while dealing with EPA Type-2 appliances. Skip to quiz!
Basic Safety Precautions
Always remember that whenever working with refrigerants, always make sure that you are wearing proper personal protective equipment (PPE), including
Safety glasses
Safety gloves
Safety shoes
Safety hat/helmet
ASHRAE Standard 15
ASHRAE Standard 15 talks about the safety of persons and property on or near the premises where refrigeration facilities are located. For us, the important part to understand in this standard is the ‘Equipment Room Requirements.’
Recall that refrigerants are toxic, and inhaling them is life-threatening. When refrigeration equipment is kept indoors, a separate room is required for them. Any equipment room must have electronic refrigerant detectors and a mechanical ventilation system running continuously.
These systems pull the outside fresh air into the equipment room from one side and exhaust the room air from the other using mechanical fans and blowers. Compare this to a kitchen exhaust fan but much larger in size.
Equipment room refrigerant detectors are electronic detectors that sense refrigerants in the air and give out an alarm. Along with the alarm, the ventilation systems also turn on and start blowing in fresh air into the room. Any traces of refrigerant outside the system indicates a refrigerant leak.
Recall that refrigerants are heavier than oxygen and settle down at the bottom of the room in case of a leak. However, ammonia (R717) is a lighter refrigerant than air and rises to the top in case it leaks. The leaked R717 will accumulate at the top of the room and won’t be fatal.
For an equipment room having R717 in the systems, a refrigerant detector is not needed. Provided the mechanical ventilation systems are working continuously so that the leaked refrigerant is being thrown out of the room. Recall that ammonia is a natural refrigerant, and there are no prohibitions on its venting.
Best Practices
Recall that a filter drier traps air, moisture, and other contaminants from the system's refrigerant. If a system is opened for servicing, repair, and maintenance works, the outside air and dust particles enter the system.
Though evacuation removes the air from the system, it cannot remove the air from the filter drier. This is because a filter drier is meant to trap air, and there is no way to remove it from within the drier. So it is a good practice to replace the filter drier every time a system is opened.
Recall that dry nitrogen is used to check for leaks and to evacuate a system. Dry nitrogen tanks are under high pressure, so the nitrogen cylinders require a pressure regulator to reduce the pressure to a safe level. A pressure regulator is required to maintain the pressure and flow of the nitrogen gas.
Recall that sight glass is a transparent glass used to check for signs of moisture inside a system. Ice or dirt may form on this sight glass at low temperatures that should be cleaned using an isopropyl alcohol spray. Isopropyl alcohol is also commonly used to de-ice car windshields during winters.
Compressor Safety Precautions
Recall that a hermetic compressor has all the components in a single shell. The compressor motor, when energized, produces a lot of heat. In this type of compressor system, the refrigerant performs the function of cooling the compressor motor.
As a safety precaution, the hermetic compressor should never be started if the system is under vacuum. Recall that during a deep vacuum, the refrigerant has been completely recovered before starting the evacuation process. The hermetic compressors’ motor winding gets damaged if energized due to overheating.
A reciprocating compressor compresses the refrigerant in a cylinder. A reciprocating compressor is very similar to a car engine.
A reciprocating compressor should never be started when the discharge service valve is closed. If the discharge service is closed, it does not allow the flow of refrigerant out from the compressor. In such situations, the compressed refrigerant will have nowhere to go and will build up high pressure in the compressor and damage it.
Pressure Relief Valve
Recall that a relief valve protects against high pressures in the system. A daily example of this might be the 'Pressure cooker' and how the cap on top of the cooker lifts to release the pressurized steam inside it.
Boilers and compressor systems in the past have reported blasts due to pressures exceeding the allowable pressure for the system. A pressure relief valve is by far the most important safety component. A pressure relief valve must protect every refrigerating system.
Multiple pressure relief valves should never be installed in series to the system lines. This is because installing multiple valves makes all other valves useless as all pressure is released out of a single valve. Also, it may result in excessive loss of the fluid due to multiple valves releasing pressure at the same time.
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