For over 30 years, Leo A. Meyer has written and published training materials for the HVAC industry. His books cover a wide range of topics, including heating and cooling, indoor air quality, sheet metal work, electricity basics, safety, and others. For more information, visit www.lamabooks.com.
A thermostatic expansion valve (TXV) is designed to maintain a specific amount of superheat at the outlet of the evaporator. If the superheat value is too high or too low, the TXV may be the cause. However, before deciding the TXV is defective, all other system causes must first be investigated and ruled out.
The correct placement and installation of the thermostatic expansion valve (TXV) sensing bulb is important to its overall performance and reliability. An incorrectly installed or placed sensing bulb can lead to several different types of system problems. Here are some general installation concerns and tips to follow when installing a TXV.
Loose electrical connections to motor terminals can cause voltage drop, overheating, and a chance of fire. For three-phase motors, a loose connection can cause single phasing — which will damage the motor.
This article deals with your personal safety when installing a new or replacement furnace. Topics covered include emergency procedures; clothing and safety gear; fall protection; electricity; lock out, tag out; GFCI; fuel safety; and confined spaces.
These conditions were noted in an energy audit report: “The fire/smoke damper was closed.” “The coils are still dirty.” These are not unusual examples. Since 40 percent of the energy used in the United States is used to operate buildings, it is obvious that a big step in making America green is to make our buildings green.
Every manufacturer of an HVAC digital control system uses the DDC to perform pretty much the same functions. The catch is that each DDC system has different ways of letting you use these functions. If you are used to operating computers, you have the basic knowledge required.
Remember that automatic control systems are automatic in operation, but not self-repairing. Unless a building has a service contract with a reputable controls contractor to inspect and calibrate the HVAC control system every six months, it is very likely that the HVAC system is not providing maximum comfort.
If you are like most in the HVAC industry, you are a hands-on person - you don‘t want to mess with a lot of theory, but just get in and get the job done. But a refrigeration system is different from most of our work.