Instructions / Assembly
OPERATION
Appliance description
12 | Accelera® 220-300 E www.stiebel-eltron-usa.com
The appliance display indicates the temperature in the upper sec-
tion of the tank. The appliance control unit operates using the
average tank temperature.
DHW heating begins when the available mixed water volume de-
creases to the percentage of maximum mixed water volume set
in the “Reload factor” parameter.
The appliance may start to heat even though the display indicates
that the thermostat is fulfilled. In this case the deviation of the
average tank temperature from the set value is greater than the
hysteresis of the integral sensor thermostat.
At ambient air temperatures lower than 46 °F (7.8 °C), the unit will
automatically enter defrost mode from time to time to remove ice
buildup on the evaporator.
For information on the heat-up time, See 17.3, “Data table”, pg.
35. The calculation of the available amount of mixed water is
based on the average cylinder temperature. The amount of mixed
water is only calculated if the water temperature in the upper
section of the cylinder is higher than 104 °F (40 °C).
DHW is normally heated by the heat pump of the appliance within
the application limits (See 17.3, “Data table”, pg. 35).
4.2.1 Electric booster element
The electric booster element is used for times of unexpectedly
high hot water demand. The element is activated manually via
the red dot push button located on the front display panel (See
5.1, “Display and controls”, pg. 13, item no. 8, “Rapid heating
key”). It is also activated automatically when the appliance is in
Automatic Mode (See 5.3.1, “Automatic Mode”, pg. 15).
In case of a heat pump failure you can start the electric emer-
gency/booster heater should the appliance develop a fault and
the fault code is higher than 256. (See 5.5.2, “Emergency back up
mode”, pg. 16).
In the event of an unexpectedly high hot water demand, the emer-
gency/booster heater can be activated with the rapid heating key
in addition to the heat pump. See 5.5.1, “Comfort heating”, pg.
16.
4.3 Appliance operation outside the application
limits
4.3.1 Ambient temperatures below the application limit
If hoar frost is growing on the evaporator fins, the hoar frost
temperature monitor switches the heat pump compressor off.
The compressor switches on automatically once the evaporator
defrosts. Defrost only works if the ambient air temperature is
more than 38 °F (3.3 °C)
f To guarantee fault-free operation of the appliance, make sure
you operate the appliance within its application limits (See
17.3, “Data table”, pg. 35).
Note
Heat-up times are longer while the evaporator is defrost-
ing.
4.3.2 Ambient temperatures above the application limit
The safety equipment switches the appliance off if the upper ap-
plication limit is exceeded.
Following a cooling time of several minutes, the appliance is
switched back on automatically. The appliance is switched off
again if the ambient temperature rises above the permissible tem-
perature value again.
f To guarantee fault-free operation of the appliance, make sure
you operate the appliance within its application limits (See
17.3, “Data table”, pg. 35).
4.4 Defrosting
Low air intake temperatures may result in the formation of hoar
frost on the evaporator, subject to relative humidity and DHW
temperature. The appliance is equipped with an electronic de-
frost monitor. DHW heating is interrupted during the defrosting
process. The appliance switches off the compressor during the
defrosting process. The fan continues to run. The defrosting pro-
cess is shown on the appliance display.
A maximum defrost time is stored in the appliance. If the maxi-
mum defrost time is exceeded, the appliance stops the defrosting
process and releases the electric booster element.
Note
Heat-up times are longer while the evaporator is defrost-
ing.
Note
The appliance starts the defrosting process as soon as
the compressor runtime reaches the "Defrost required"
time span stored in the appliance.
4.5 Freeze protection
The appliance activates a freeze protection function if the integral
sensor in the DHW tank detects a temperature below 50 °F (10 °C).
The appliance then heats the water in parallel mode by using both
the heat pump and the electric booster element. The heat pump
and electric booster element switch off once the temperature de-
tected by the integral sensor is more than 65 °F (18 °C).