HVAC final exam, unit 14 Correct Questions & Answers.

When a water regulating valve is used to control the head pressure of a water-cooled system, the valve's spring is acting against which pressure to modulate the water flow? - ANSWER Head pressure of the system To prove that the combustion blower motor is operating before ignition, a ______ would be used. - ANSWER Sail switch The difference between system overshoot and system lag is called? - ANSWER Temperature swing The purpose of a heat anticipator is to_____. - ANSWER Reduce the temperature swing of a conditioned space To control ice build-up on a heat pump outdoor coil in the heating cycle, a ____ is attached to a large diaphragm. - ANSWER Microswitch A low pressure control has a "high event" and a "differential" setting. The technician wants the system to turn on at 28 psig and shut down at 2 psig. What would be the proper settings? - ANSWER High event: 28 psig, differential: 26 psig Line voltage thermostats have heavier and use which type of sensing element? - ANSWER all of the above The heater in the thermostat control circuit in the cooling mode is active when the - ANSWER Cooling contact is open If the suction pressure of a system is 60 psi and the oil pump is 85 psig, what is the net oil pressure? - ANSWER 25 psig What is meant by the term "detent" ? - ANSWER Rapid making breaking of a contact The ______ must determine what the current flow is through the heating control circuit. - ANSWER heating technician The cold anticipator is wired in _____ with the mercury bulb cooling contacts, and is energized during the off cycle. - ANSWER Parallel Where would a water regulating valve that is controlling head pressure be installed? - ANSWER Water circuit at inlet of condenser