A Thermostatic Expansion Valve (TXV) is a metering device in certain HVAC systems. The TXV regulates the rate of how fast refrigerant enters the evaporator coil and prevents excess refrigerant from returning to the condenser.
Yes, I know … I can hear the yawns as I type this information myself. However, this information is important to understand, and I will explain why.
But first, I am reminded of a story I heard from a homeowner this past August. This customer was having problems with his HVAC system, even though it was only two years old. He called the company that installed his unit because his brand-new unit was not reaching the correct temperature. The company sent out a technician, who could not figure out what was wrong.
It turns out the tech was only checking the sub-cooling, which was correct according to manufacturer specs. However, he did not think to check the Superheat, which refers to the amount of heat the refrigerant absorbs after it changes state.
This technician told the homeowner, “Well, everything is functioning; it must be Gremlins messing with your new system.” Needless to say, the homeowner was not amused by this, and called American Heritage Air. We sent one of our more experienced NATE-certified technicians to evaluate the system and determine what was wrong.
So, how does this story relate to the TXV? Well, all metering devices control the flow of the refrigerant. The TXV was invented specifically to control the Superheat.
Having the correct Superheat range is important because it affects the unit’s efficiency. If the Superheat is out of range even by a little, it literally eats away the mechanical components of a compressor. This is just as bad for an air conditioner as it sounds: it reduces its life span and efficiency.
American Heritage Air has encountered this problem at an alarming rate this past summer. We have found several homeowners with new systems with incorrect Superheat ranges and, thus, failing compressors.
The recommended Superheat range should be between 8-15 degrees. Most HVAC technicians are misinformed about what the correct range of Superheat should be and why it is vital to have it. With the rising cost of air conditioning systems, it is imperative that the air conditioning company you choose to replace your HVAC system understands Superheat and ensures your system is within that range during HVAC replacement.
If you are facing similar problems with your HVAC system, or if you plan to have a new system installed soon, please call us at (972) 559-4477. We will send out a NATE-certified technician to evaluate your particular situation and determine how we can best help!
