REMEHA Avanta Plus 24s, Installation And Service Manual

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61
o
In normal operation, the boiler’s flue gas discharge will
produce a visible white condensing “plume” and therefore care
should be taken when choosing a location for the terminal.
Combi boiler operation
The Remeha Avanta Plus 28c, 35c and 39c are combination
boilers with an integral plate heat exchanger providing instant
domestic hot water. On opening a hot water tap, detected by
a flow sensor, which is located on the cold water inlet side of
the heat exchanger detects the demand. This sensor then acti-
vates the motorised three-way valve to divert primary flow to
the plate heat exchanger which raises the temperature of the
cold water supply by a minimum of 35°C to provide domestic
hot water. Once the demand for hot water stops the motorised
valve automatically returns to the DHW position. This three-
way valve is electrically controlled by the ‘
abc
®
’ control and
only consumes power when it is changing to a different posi-
tion.
The plate heat exchanger is protected from debris by two fil-
ters one in the cold water supply and one in the primary flow
to the diverting valve – Note: the primary flow filter self cleans
when the flow reverts back to heating mode.
System boiler operation
The Remeha Avanta Plus 24s the same design and layout
as the combi range without the DHW components (three way
valve and plate heat exchanger).
8.3.1 Regulating
The Remeha Avanta Plus is a fully modulating boiler and can
be regulated using one or more of the following methods;
1. Open Therm – 2 wire interface compatible with the Remeha
Celcia 15 room compensator and the Remeha Celcia 20
outside weather compensator or with any other proprietor’s
OpenTherm
®
controls.
2. Open Therm thermostat in combination with an external
time clock.
3. On/Off room thermostat – volt free (on the X9 terminal
strip).
4. On/Off room thermostat – 230 V (on the X2 terminal strip).
5. 230 V Switching time clock - compatible with the Remeha
two channel time clock or with any other proprietor’s time
clock. For further details see
par. 2.8.
8.3.2 Advanced boiler control (‘abc®’-control)
An intelligent advanced boiler control (‘ abc
®
’ ) continuously
monitors the boiler conditions and ensures a very reliable
supply of heat. This control system is adept at dealing with
negative influences from the system such as flow reduction,
airflow problems and alike. In the event of such influences, the
boiler will not go to “lock-out” failure mode, but will in the first
instance modulate back, and if necessary, depending on the
nature of the circumstances, will temporarily switch off (shut-
down or control stop), and then after a short while simply try
again.