thank god heat pump mod is over
an air-to-air heat pump has many of the same components as an air conditioning system. the major difference is that a heat pump also has a
reversing valve
the outdoor coil is frozen solid on a "no heat" service call. the most likely reason is
outdoor fan is inoperable
when the heat pump compressor has malfunctioned, the customer has the option to switch the system into?
emergency heat mode
how may a lockout (impedance) relay be reset
simply disconnect power to the unit momentarily
what is the industry standard for a deep vacuum?
maintain 500 microns for 15 mins
what is the difference between "demand defrost" and timed defrost?
demand defrost happens only when needed and timed defrost is based on time/temperature
in order to determine a heat pumps balance point, you must first calculate?
the buildings heat load
start-up with a night set back digital thermostat requires the technician to always?
teach the customer how to program the thermostat
the temperature difference between the 1st and 2nd bulbs for heating on a heat pump
approximately 2 degrees
good service practice for installation of a reversing valve
use heat paste and wet rag while brazing in the new valve
the thermostat that controls the auxiliary electric heat according to the outdoor temperature is called the what?
outdoor ambient thermostat
heat pumps are sized to handle the
cooling load
the heat pump defrost board can me manipulated by the technician to
simulate a defrost cycle
seer is calculated by
dividing the BTU'S removed by the watts consumed during the cooling season
off-cycle crankcase heat is provided by
a small amount of current is passed through the start capacitor to heat the start winding
the outdoor temperature at which the heat pump provides the same amount of heat as the heat loss of the conditioned space without auxiliary heat is known as the?
initial balance point
on a heat pump, which coil is considered the evaporator coil?
depends of mode of operation
an air-to-air heat pump outdoor unit is most efficient if located in?
in a moderate climate zone
if the indoor fan is operated at an excessive speed in the cooling mode
the system will not properly removed the humidity from the conditioned space
what control operates the 1st stage of the secondary heat
the second heating stage of the indoor thermostat
at what temperature is an outdoor ambient thermostat normally set?
slighty above the initial balance point
room thermostats for heat pumps should be installed?
as near to the main return air grille as possible
which of the following are innovations that may be found on high efficiency units?
ECM motors
the most preferred method of charging any system in the field is?
by weight
what is the industry standard for maximum duration for defrost?
maximum of 10 minutes
what is the recommended CFM across the evaporator coil of a heat pump?
400 to 450 CFM
if manufacturers specifications are not available, a good way to calculate cubic feet per minute
use temperature rise on emergency heat mode
heat pump heating mode efficiency is rated in
HSPF
you are staring up a split system heat pump for the first time. the outdoor ambient temperature is 60 degrees. you check the temperature split across the indoor coil in the heat mode and find it is 38 degrees. you switch to cooling mode and determine a temperature split of 29. the most likey corrective action (relative to airflow) is
increase the indoor fan speed
on a water source heat pump, the heat mode water regulating valve must be
direct acting
a r410a heat pump operating in the heating mode has a suction pressure of 50 psig and head pressure of 285 psig has a compression ratio of
7.7.1
which type of heat pump does not require a defrost cycel
water source heat pump
a r-22 heat pump operating in the cooling moce has suction pressure of 68 psig. adding 2 psig for pressure drop in the coil, the true outlet pressure of 70 psig. the temperature of the suction line at the oulet of the evaporator is 53 degrees. what is the superheat
12 degrees
on a time initiation/temperature termination defrost, the defrost time clock has one n.o. and one n.c. switch. when do th positions of these switches change?
every 30 or 90 minutes depending on the cam installed in the timer
what would be the result of closing registers in rooms that are uninhabited while operating in the heating mode?
the suction pressure will drop and the temperature will rise decreasing the life span of the unit