HVAC Study

In a heat pump system, the role of the evaporator and condenser changes when it becomes heater from cooler. In summer time, it is a cooler, outside unit is the condenser, inside is the evaporator. But in winter time, the outside unit becomes evaporator and inside unit becomes condenser, the refrigerant moves at a different direction, that is, the refrigerant's moving direction is reversed when it becomes a heater from a cooler. The moving direction changes again when it becomes a cooler from a heater. However, the compressor can never change it refrigerant direction, that is the reason why heat pump system needs reverse value and many cases it also has a refrigerant accumulator in front of the compressor, the refrigerant accumulator is to make sure that no liquid will ever enter compressor. The following is a AC system chart. not a heatpump system chart.

1987 Montreal protocol signed by the United States and 22 other nations. 1990 Clean Air Act (CAA) Amendment of 1990 assigns EPA authority to control ozone depleting substances. 7/1/1992 It is illegal under Federal law to knowingly vent or release refrigerants in Class I(CFC) or Class II(HCFC) into the environment. 8/12/1993 All persons/contractors/shops must certify ownership of recovery machines to EPA. To satisfy this requirement all recovery (to include home made) must be registered with the regional EPA office for your area using an OMB# 2060-0256 Form. 10/15/1993 All technicians must take a closed book examination to become certified under EPA rules. 11/15/1993 Recovery and recycling machines must meet stricter EPA standards pertaining to evacuation levels for machines manufactured after this date. 11/15/1994 A technician cannot perform work on an air conditioning or refrigeration system requiring access to the refrigerant charge unless the technician is certified for that type of...

New comers often mixed up EPA 608 certificates and state licenses. When you actually pass EPA 608 exams, you are certified and you can take these exams any time, some providers even provide online tests where you can take the test anywhere you like but you may need to have a camera. Once you have the certificates, you can purchase various refrigerants. License is a complete different thing. To obtain a HVACR license you need to also pass normally a state board of refrigeration contractors sponsored exams with normally 4000 hours of experiences in handling commercial refrigeration. For example, NC state board of refrigeration contractors says to be eligible to take the exam, you must:       (1) Submit an application to the board, with the non-refundable examination-license fee.       (2) Verify that you have acquired at least 4000 hours of commercial refrigeration experience.