20
Defrost cycle (timed)
The ice which is produced on the outdoor coil during the
heating cycle must be eliminated when it begins to block the
coil.
The defrost cycle begins after a period selected between 30,
60 & 90 minutes from the start-up or the last defrosting, and
when the evaporation temperature drops to -5 °C or less.
The logic module activates the defrost relay, which:
- Activates the 4-way valve to go into the cooling cycle.
- Switches off the outdoor fan.
The defrost cycle finishes when the liquid temperature is
sufficiently high, measured by a thermistor 13 °C, or when, if
it does not heat up, it reaches a minimum of 7 °C for a 1 minute
period; also after 12 minutes from its beginning.
When the defrost cycle finishes, the logic module
disconnects the defrost relay, reestablishing normal
operating conditions of the heating cycle.
If the unit triess to go into another defrost cycle in less than 5
minutes, the logic module switches it off, leaving the system
in lock-out.
Operating at -15°C
(optionally -5, -10, -20)
When the outdoor temperature is less than -15°C there is no
justification for running the compressor with the limited
amount of heat it generates.
If the logic module detects, through a thermitor in the exterior
air entry, a temperature lower than -15°C, it acts as follows:
- It disconnects the compressor.
- It switches on the emergency heater (if there is one
installed) controlled by the thermostat's second stage. (The
auxiliary heater will also continue to function, governed by
the thermostat's second stage).
- It leaves the indoor fan functioning under the first heating
stage of the thermostat.
Operation on emergency heat
When the thermostat operation mode is in the emergency
heat position.
- Compressor will be in lockout.
- The supplementary and emergency electric heaters, if
installed, will be controlled by the first stage of the thermo-
stat.
Other safety features of the electric circuit
- The compressor is protected against overheating and the
failure of a phase by a solid state protector with three
sensors embedded in the windings.
- The control circuit is protected by a fuse.
- In general all the casing and components are protected by
an earth circuit.
Compressor crankcase oil heater
The compressor is equipped with an electric heater in the
crankcase, which heats the oil to prevent an excessive
concentration of refrigerant in it during the periods when it
does not operate.
If the main disconnect switch has been off for some time,
before heat pump is started switch should have been on for
at least 8 hours.
This is necessary to drive out any refrigerant that may be
accumulated inside the compressor.
Before finalising the installation
Verify that:
- The voltage is always between 198-
254 V or 342-436 V.
- The gauge of the supply cable is at
least that which is recommended in
the corresponding electrical dia-
grams.
- Instructions have been given to the
users on how to operate the system.
- The condensation drainage is
perfectly assembled and their are no
leaks in the water circuit.
- The need to clean the air filter has
been communicated.
- The guarantee split has been filled
in.
- Maintenance instructions have been
given or a contract has been made
for periodic servicing.
