System design, performance, and service conditions must be evaluated when retrofitting with a zeotropic or near-azeotropic refrigerant blend. Always follow the refrigerant manufacturer’s retrofit guidelines before retrofitting with any refrigerant, or system performance could be affected and/or injury may occur.
Measuring the evaporator’s superheat value is an important part of analyzing a system’s performance. If a lower-than-normal value is measured, too much refrigerant is entering the evaporator for the heat load. If a higher-than-normal value is measured, too little refrigerant is entering the evaporator for the heat load.
Bob and Tim were at the shop after a day of service calls. The weather was still hot, 93°F, and Bob said, “We just did a service call with a system that was overcharged and had an orifice expansion device. I would like to go into further details with you on a system with a thermostatic expansion valve (TXV) for an expansion device.”
Bob and Tim were on their way to a service call with a new customer. When they got to the job, the customer explained, "The unit was not cooling and I had a company come out for a service call. The unit seemed to work OK last week when it was a little cooler outside, but this week it has warmed up and the unit is not functioning as well."
What is a super tech? A super tech is one who eats, sleeps, and breathes HVAC. He may be a contractor, manager, or technician, but, above all, he is a perfectionist. And his greatest enemy is the callback.
Bob and Tim were on their way to a no cooling call at a residence. They were pretty sure that it was a low refrigerant call. Bob said, “I hope that we can put the last lesson into practical practice. We have gone to a great deal of trouble to understand superheat.”
Bob and Tim were in the company conference room where Bob is set to give Tim some extra training at Tim’s suggestion. Bob said, “Tim, you asked for more explanation of what superheat is. This is not a very simple topic. It will take a couple of meetings to go into detail about it.”