andrews MAXXflo - Temporary Water Heater Temperature Change; Circulation Pump and Storage Tanks

MAXXo Water Heater
1818
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. is makes it possible, for example, to carry out
Legionella ushing. (See page 32).
e water heater temperature changes when the contacts
connected to terminals BT1 – BT2 are closed. e water
heater temperature goes back to normal operation when
these contacts are opened again.
If the temperature change is used for Legionella ushing,
it is possible to return the water heater temperature to
normal operation before the timer programme nishes.
is 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. e 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 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. e 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.
e 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 MAXXo storage tanks are available in
200 and 300 litre sizes, models HWST200 and HWST300.
ese tanks are tted with a thermostat for use as above.
See below for schematic system design and pages 16 & 18
for tank dimensions and wiring diagram.
FIG 8 – SCHEMATIC SYSTEM DESIGN
SECTION 3 • INSTALLATION