Normal Mode; Figure 3 - Operating Modes - Rheem RUUD Iraining Manual

Normal Mode

Under no circumstances will the compressor and lower electric heating element
Start Sequence
1. If lower tank thermostat is less than 70ºF and
upper tank thermostat is less than 75ºF, the water
pump and both elements are energized until
lower tank thermostat is 80ºF. This Pre-Warm
mode prevents the compressor system from
experiencing excessively low discharge pressure.
2. Compressor then starts as required by tank
temperatures greater than 80ºF.
3. Evaporator fan start – low speed.
4. Water pump starts and operates as required by
tank temperature.
5. Upper heating element will remain off during the start sequence.
6. For the first 90 seconds no operational control will be polled for temperature values
7. After 90 seconds of operation:
a. If ST (suction temperature) is below 47ºF, the evaporator fan is adjusted to high
speed operation and an additional 90 second delay is started. ST is not polled
until after the additional delay.
b. AS, ambient temperature and WT, water temperature leaving the condenser are
polled. If AS is less than 40ºF but not greater than 120ºF and WT is less than
133ºF, compressor operation continues. If not, lower electric heating element
operation is allowed.
Run Sequence
1. Fan speed will be held at the value determined during the Start Sequence.
2. Water pump will modulate speed as required.
3. Compressor operation continues until lower tank thermostat or condenser water
temperature limits are reached.
4. The upper electric heating element operation is locked out during the first 30 minutes of
each compressor run cycle.
5. Afterwards, the upper electric heating element is operated as long as compressor
operation is permitted. This heater will continue operation until the upper thermostat
temperature limits are reached.
6. The lower electric heating element operation is locked out while the compressor and/or
the upper heating element are operating in Normal Mode.
7. Lower electric heating element operation is allowed whenever compressor and upper
heating element operation is no longer required and the lower tank thermostat remains to
be satisfied.
8. If compressor is not utilized, evaporator fan will be de-energized
9. Compressor, upper electric heating element, and lower electric heating element will
deenergize as operational temperatures are reached
be allowed to operate at the same time.
14
Heat Pump Water Heater
Figure 3 – Operating Modes