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SRC-131 Hotel Controller Manual
7
Note - When the SRC-131 calls heating or cooling the SRC-131 will drive both the relays and the
0-10V outputs simultaneously. This way the SRC-131 can call a circulating water pump via the relays as it
controls room temperature with valves if needed.
4.1
0-10v Outputs
To permit the control of modulating heating and cooling valves as well as variable speed DC fan
motors or variable capacity HVAC systems the SRC-131 has been fitted with 3 x 0-10V outputs.
The 0-10V outputs in the SRC-131 are PI (Proportional Integral) controlled. This control method provides the
most accurate and cost effective way to control heating and cooling valves by ensuring set temperate are reached
as quickly and efficiently as possible while reducing temperature overshoot.
As the SRC-131 is fitted with both relays as well as 0-10V outputs to control HVAC systems there may be some
slight disparity between the thermostat display and the 0-10V outputs actions. The SRC-131 displays the relay
actions more than the actions of the 0-10V outputs on the LCD. In most cases these are very closely matched
however as the 0-10v outputs have the capability of providing finer control than do the ON/OFF relays the
heating and cooling calls may have started slightly before indicated on the thermostat display. This is true of
the fan also.
4.2
A1 – Cool
This output is used to control a cooling valve.
4.3
A2 – Heat
This output is used to control a heating valve.
4.4
A3 – Fan
This output is used to control a variable speed fan or a variable
capacity AC system. If the fan mode is set to Auto speed the 0-
10V output will vary between these two values based on
calculated demand. If the user selects LOW speed, the 0-10V
output will be fixed at 3.3VDC, when Medium speed is selected the 0-10V output
will be fixed at 6.6VDC. High speed is set to 10VDC.
The installer menu provides the following settings for the control of the three 0-10V outputs.
4.5
Time Interval
Time interval sets the running average calculation time. The smaller the number the faster the 0-
10V output will respond to room temperature changes. Range is 10 – 300 seconds.
4.6
Direction
Forward action 0V = 0% open and 10V = 100% open; reverse action sets 0V = 100% open and 10V
= 0% open.
