HVAC
Simple question that gets answered differently depending on who's in the room. When brazing copper refrigerant lines, what nitrogen purge pressure are you using, and why that number? I've heard 2 PS...
Carrier 38MGQB36 VRF outdoor unit, 8 indoor units, 14 months in service. Started getting E9 communication faults 3 weeks ago. Random IDUs drop, no pattern to which unit. Communication wiring: 3-wire ...
Doing a Manual J for a 2,000 sq ft home in Phoenix, AZ (design temp 110°F). The calc is spitting out 58,000 BTU cooling load which rounds to a 5-ton system. That feels large even for Phoenix. Existin...
Still learning refrigeration theory in school. We've been taught that TXV systems should be charged by subcooling, not superheat. But my instructor also said superheat tells you about evaporator perfo...
HVAC student, 6 months in. We had a lab exercise today where we induced a low-charge condition on a practice unit. I expected to see icing at the outdoor unit (evaporator) but the ice formed on the su...
With R-410A phase-down underway, our distributor is pushing us toward R-454B (Opteon XL41) equipment. But I'm also seeing R-32 units from Mitsubishi and Daikin at competitive pricing. For those alrea...
Customer has a Mitsubishi MXZ-3C30NAHZ hyper-heat system, two heads. Works great above 25°F. Below 25°F, they're complaining about it "not heating" and the aux electric strip is running constantly. C...