tekmar 667 Snow Detector & Melting Control Installation - Manual (Page 8)

8 of 32 © 2009 D 667 - 03/09
Section C3: No Boiler Sensor
NO BOILER SENSOR (Boil SENS = NONE)
The 667 is capable of operating without a boiler sensor if desired. Without a boiler sensor,
the 667 is unable to provide boiler protection. In this mode of operation, the Boiler contact
is used to provide a boiler enable. When the mixing device begins to ramp up, the Boiler
contact on the 667 closes. The Boiler contact remains closed until the mixing device no
longer requires heat. This type of application is typical if the 667 is drawing heat from a
source that already incorporates some form of boiler protection.
Auto Differential (AUTO)
If the AUTO differential is selected, the 667 automatically adjusts
the Differential setting under the current load conditions to avoid
short cycling.
Sno
wmelting Load
On
Differential
Off
Time
Section C2: Boiler Return Sensor
BOILER SENSOR ON THE RETURN (Boil SENS = RET)
The boiler sensor should be located on the boiler return if the 667 is one of many controls
that can call for boiler operation. When in the return mode, the 667 provides a boiler
enable through the Boiler contact. The 667 no longer tries to control the boiler supply water
temperature directly, but allows the boiler to operate at its operating Aquastat setting when
required. If this mode of operation is selected, the boiler pump should either operate
continuously, or be operated in parallel with the System Pump contact (Sys P1). When the
mixing device begins to ramp up, the Boiler contact closes on the 667. The Boiler contact
remains closed until the mixing device no longer requires heat. With the sensor on the
boiler return, the 667 is still capable of providing boiler protection as described in section
A.