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18. Anti-Freeze Control
Glycol cannot be used in QAHV primary circuits. Therefore, heating of the external pipe work is
necessary, this can be achieved by trace heating or by utilizing the QAHV anti-freeze control method (This
is the preferred method).
The Anti-freeze method is switched on by using SW2-5 ON
A Volt-free contact from TB8 terminals 86 & 87 enter a closed state,
This then operates the 3-way valve to direct the cooled water, residual in the external pipework, back to
the bottom of the warm cylinder. Furthermore, this can also be used to control a third-party anti-freeze
device.
Anti-freeze control
Pump will be running to prevent from freezing
Pump ON: Outdoor temperature<1˚C and Inlet water temperature<3˚C
Pump OFF: Outdoor temperature>3˚C or Inlet water temperature>5˚C, the pump will operate for at least
3 minutes
The control method can be changed according to the system type at site. The following two items can be
changed.
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