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TM_i-BX(-N)_NC05_00_06_20_EN
5
MANAGEMENT OF DOMESTIC HOT WATER (DHW)
5.1
MANAGEMENT OF THE DHW 3-WAY VALVE
The DHW 3-way valve is used in systems producing domestic hot water for storage in a storage tank.
It's used to divert the water flow from the system to the DHW storage tank.
The resources (pump, compressor and 3-way valve) must be coordinated, so that during the switching on phase system water is not sent to the
domestic hot water storage tank, in order to avoid cooling it down, as this water is normally colder (particularly during the summer time - system cool
-) than the water already stored, and also to avoid to send stored domestic hot water to the system, when switching from DHW to system.
This need is more evident the slower the 3-way valve is in switching. As the switching time is a specific characteristic of each valve, it must be set
using parameter 0231, so that switching can take place with the pump and the compressor off (the compressor will stop and then restart, meeting the
set safety time scales).
Switching will take place based on the function described below (from system to domestic hot water and vice versa):
Compressor
ON
OFF
Pump
ON
OFF
3-way
ON
OFF
In case of defrost activities during the production of domestic hot water, the 3-way valve will switch towards the system. This is to avoid cooling down
the storage tank during to the inversion of the cycle (the switching towards the system will also take place if "DHW" only operating mode is set).
Only during defrost, will the 3-way valve be switched directly towards the system (and at the end of defrost towards the domestic hot water), without
switching off the water pump, and therefore without complying with all the delays described before.
In the idle condition, the 3-way valve is always switched towards the system; it will only be switched towards the domestic hot water during the
production of domestic hot water, or if the unit is set to DHW operation mode only.
For the default values of the various parameters, see the parameters table.
MEHITS S.p.A.
●
TECHNICAL MANUAL
Always respected are Compr essor ON-ON minimum time
and Compr essor OFF-ON minimum time
3-way valve switch time (0231)
Delay OFF compressor OFF pump
(131J, 131L)
57
Delay ON pump O N compressor
(131H)
T[sec]
Version NC05 - Translation of the Original Instructions
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