Heat Pump System - Lennox LXTFF01M Manual

switched off, the fan keeps running to cool the heater down.
In this type of system it is possible to have a neutral zone
regulation setting the automatic heating/ cooling selection
(P02=1).
In case the cut-off temperature function is used in this system,
the fan will never be inhibited while in heating mode.
INTEGRATING ELECTRIC HEATER SYSTEM
This regulator can be confi gured (P01=3) to manage a special
plant type featuring two heating systems: one with a hot water
fl ow controlled by a valve, the other with an integrating electric
heater. In this mode the regulator is only driving one valve wired
at the cooling output to manage a special plant type featuring
two heating systems: one with a hot water fl ow controlled by a
valve, the other with an integrating electric heater. In this mode
the regulator is only driving one valve wired at the cooling output
and one integrating electric heater wired at the heating output.
The relevant wiring diagram is in Fig. 8 e and f. The valve is
driven as in a two pipes system: according to the heating or
cooling setting of the controller the relevant fl ow of hot or cool
water is managed.
The electric heater is turned on as an additional (integrating)
heat source whenever, in heating mode, the room temperature
falls below the set point temperature by a ∆ setpoint that can be
confi gured in parameter C18.
In cooling mode it is possible to have a neutral zone regulation
by setting a neutral zone width greater than zero on P19. In this
case cooling is achieved by activating the valve, while heating by
activating the electric heater.
In this type of system it is suggested to set a delay on the fan
switch-off on P21, so that when the electric heater is switched off,
the fan keeps running to cool the heater down.
38
In case the cut-off temperature function is
used in this system, the fan will never be
inhibited while in heating mode, since the electrical heater will be
turned on in advance instead.

HEAT PUMP SYSTEM

The regulator can be confi gured to manage a heat pump
system (P01=4) thus controlling a 4-way valve wired at the heating
output and a compressor at the cooling output.
The wiring diagram is shown in Fig. 8 g. The 4-way valve output
is always turned on or off according to the heating or cooling
setting of the regulator.
In case the "EUROPEAN" type of driving is chosen, the 4-way
valve is powered in heating mode and left unpowered in cooling.
Alternatively, with the valve wired at terminal 10, the driving logic
is reversed: the valve is powered in cooling and left unpowered
in heating ("USA" type).
The compressor output is active whenever it is necessary to
"pump" the heat, that is when the room needs to be cooled down
or heated up. It is advisable to set a delay on the compressor
output (parameter C09) in order to avoid too frequent turn-off and
turn-on.
In the heat pump mode the supply water temperature sensor can
still be wired and its purpose is for protection against freezing or
overheating of the heat exchanger. Should the supply sensor,
when in cooling mode, detect a temperature lower than C02, the
regulator stops the compressor (anti-freeze protection).
On the other hand, should the supply sensor, when in heating
mode, detect a temperature higher than the value stored in
parameter P22, the regulator stops again the compressor (over-
heat protection).
LXTFF01M-IOM-1511