Boiler operation – tekmar 362 Mixing Control Installation User Manual

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Section D1

Boiler Supply

Sensor

Section D2

Boiler Return

Sensor

Section D3

No Boiler Sensor

Section D: Boiler Operation (Mode —1— and —2— )

WARM WEATHER SHUT DOWN (WWSD)

Since a slab sensor is not in use, the Warm Weather Shut Down is determined only from the outdoor air temperature. Once the outdoor
air temperature rises above the WWSD setting, the control goes into a WWSD and ignores any demand for Idling or Melting. Also the
word WWSD is displayed when viewing the SNOWMELT item in the View Menu.

IDLING MODE (IDLING)

When the snow melting system starts from a cold temperature, the time required for the slab to reach the Melting temperature may be
excessive. To decrease this start up time, the slab can be maintained at an Idling temperature. The Idle feature is also useful for
preventing frost and light ice formation. When the control is in idling mode, the Idling pointer is visible in the View menu and the word
IDLE can be read when looking at the SNOWMELT item in the View menu. The IDLING setting in the Adjust menu sets the desired slab
sensor temperature.

MELTING MODE (MELTING)

The Mixing Control 362 is a manual snow melting control. In order for the snow melting system to be started, one of the three methods
described in Section C2 must be used. When the control is in the melting mode, the Melting pointer is displayed in the View Menu and
either EXT, INF or a running time can be read when viewing the SNOWMELTitem in the View menu. The MELTING setting in the Adjust
menu sets the desired slab surface temperature.

Section D1: Boiler Supply Sensor

BOILER SENSOR ON THE SUPPLY (Boil SENS = SUP)

Mode 1: Heating

The boiler sensor can be located on the boiler supply if the 362 is the only control that is
operating the boiler. When in the supply mode, the 362 determines the required operating
temperature for the boiler supply and cycles the

Boiler contact in order to maintain the

correct boiler supply water temperature. If this mode of operation is selected, the boiler
pump should either operate continuously or be operated in parallel with the Mixing Pump
contact (Mix Pmp). The boiler pump should not be operated by the operating aquastat as
this may lead to improper cycling of the boiler because of inconsistent flow past the boiler
supply sensor. This mode of operation only works if the Boil SENS item is set to SUP.

Mode 2: Snow Melting

When operating a boiler that is dedicated to a snow melting system, the 362 is designed to operate the boiler as efficiently as possible.
The boiler is cycled based on the mixing supply water temperature. This is to provide longer and more efficient boiler cycles. This mode
of operation only works if the Boil SENS item is set to SUP.

BOILER TARGET TEMPERATURE (Boil TRG)

Mode 1: Heating

When operating in Mode 1, the Boiler Target temperature is determined by the operation of the mixing device. The Mixing Control
362 uses a method called

Boiler Load Reset in order to determine the required boiler supply water temperature. The 362 operates

the boiler at a supply temperature that is sufficient to satisfy the requirements of the mixing device. If the boiler supply water
temperature is not sufficient, the 362 increases the boiler target temperature. If the boiler supply water temperature is more than
sufficient, the 362 decreases the boiler target temperature. If the control does not have a requirement for heat from the boiler, it does
not show a boiler target temperature. Instead, - - - is displayed in the LCD.

Mode 2: Snow Melting

When operating in Mode 2, the boiler target temperature is determined by the mixing target temperature. The mixing target
temperature is automatically determined by the control.