Temporary Water Heater Temperature Change; Circulation Pump And Storage Tanks - andrews MAXXflo CWH30/200 Installation Manual, Operation And Maintenance Manual

TEMPORARY WATER HEATER
TEMPERATURE CHANGE
It is possible to change the water heater temperature
remotely via a timer programme. First of all, the new
desired water heater temperature is set at a value higher
or lower than the water heater temperature during normal
operation. This makes it possible, for example, to carry
out Legionella flushing. (See page 32).
The water heater temperature changes when the
contacts connected to terminals BT1 – BT2 are closed.
The water heater temperature goes back to normal
operation when these contacts are opened again.
If the temperature change is used for Legionella flushing,
it is possible to return the water heater temperature to
normal operation before the timer programme finishes.
This happens on the basis of a temperature
measurement, for example at the end of a circulation line
(secondary return). For this purpose, a 10K NTC
temperature sensor (part number E674) must be
connected to the terminals LS1 – LS2. The water heater
temperature now goes back to normal operation if the
temperature is higher at the measuring point than the
secondary pre-set water heater temperature minus 5°C
FIG 8 – SCHEMATIC SYSTEM DESIGN
INSTALLATION • SECTION 3 XXXXXXXXX • SECTION XX
for 20 minutes. If, for example, the secondary pre-set
water heater temperature is set at 70°C, the water heater
temperature returns back to normal operation as soon as
the temperature at the secondary measuring point has
been above 65°C for more than 20 minutes.
CIRCULATION PUMP AND STORAGE
TANKS
A circulation pump (maximum 0.7 A) can be connected at
the terminal pump L – pump N. The circulation pump can
then be controlled by a thermostat connected to
terminals TH1-TH2. Connecting the contacts of the
thermostat then activates the circulation pump.
The application can be used when the water heater is
combined with a separate storage tank.
As soon as the temperature in the tank gets too low, the
thermostat will activate the pump so the tank is heated up
again. Matching MAXXflo storage tanks are available in
200 and 300 litre sizes, models HWST200 and
HWST300. These tanks are fitted with a thermostat for
use as above. See below for schematic system design
and pages 16 & 18 for tank dimensions and wiring
diagram.
17 17