TM017 Rheem Air Sourced Heat Pump Service Instructions REV: C
Date of Issue: 5/11/05
This document is stored and maintained electronically by
Service. All printed copies not bearing this statement in RED are deemed “uncontrolled”.
20
Component Test 8
Warning – “Live” equipment Personal Protective Equipment should be worn when
conducting this test.
Check for persistent air bubbles through
sight glass of receiver/filter drier. Fit
gauges to the low side access valve and
observe the suction pressure. A suction
pressure of less than 100kPa may
indicate a refrigerant leak or a
malfunctioning TX valve.
Refrigerant Charge
Pressure
Ratio
Current draw (Amps at
240VAC)
2.5
2.8 – 3.0
3.0
3.2 – 3.4
3.5
3.4 – 3.6
4.0
3.7 – 3.9
4.5
4.0 – 4.2
5.0
4.3 – 4.5
5.5
4.6 – 4.8
6.0
4.9 – 5.1
6.5
5.2 – 5.4
In addition to the average water temperature -
discharge pressure table, on page 19,
measuring the compressor current draw is an
alternative method to check the operation of
the system. The compressor current draw is
dependant on the pressure ratio of the suction
and discharge lines. The table opposite
details indicative current draw for a given
pressure ration.
Pressure ratio = Discharge pressure (gauge) /
Suction pressure (gauge)
7.0
5.4 – 5.6
Indication of correct refrigerant charge
The receiver/filter dryer sight glass should show clear liquid, a few small bubbles might be
visible during initial start up of the system or when the TX valve opens quickly, however
clear liquid should return shortly after. Compressor current draw and system pressures are
within the normal range and temperatures should be consistent with system pressure.
Indication of undercharged system
Bubbles persist for a significant amount of time or repeat often. Compressor current draw
is low together with low system pressures. If sight glass indicates clear gas, not liquid, and
current draw is very low combined with low discharge line temperature then the system is
totally empty.
Note:
Unusual current draw or low suction pressure can be a sign of other
problems such as a blockage or malfunctioning TX valve.
Indication of overcharged system
Continuous liquid through sight glass, evaporator tends to flood, head pressure high,
compressor current draw high and compressor noisy.
Note:
Unusual current draw or high
head pressure can be a sign of other problems such as a blockage or malfunctioning TX
valve.