Temperature Controller Operation For Modulating Boilers - Thermal Solutions EVO-500 Installation, Operating And Service Instructions

IX. Temperature Controller Operation for Modulating Boilers
A. Description
The microprocessor based temperature controller is utilized for all modulating Thermal Solutions water boilers. The basic
function of the controller is to modulate the firing rate of the burner in response to the boiler heat load. The controller monitors
the boiler water temperature through the use of a sensor located in the boiler pressure vessel. The controller compares the boiler
water temperature to the controller's user defined operating set-point temperature.
An output signal from the microprocessor varies the blower speed through the use of a variable frequency drive (VFD). The gas
valve regulates an appropriate amount of gas flow for a given air flow or blower speed. The user may adjust the operating set-
point temperature for a given application. In addition, the controller has the ability to change to an alternate set-point through an
external signal for low load conditions (i.e. weekend use, night setback). Outdoor reset is another standard feature, allowing the
boiler operating temperature to vary based on the outdoor ambient temperature. The typical result is a higher seasonal efficiency.
Other features include:
Low Fire Hold
Multiple Set Points
Digital Inputs
B. Set-Up
All of the control parameters have been set at the factory. There are a few parameters called "Process Parameters" that must be
defined by a qualified operator. The table below will help serve as a reference and record when making adjustments.
Parameter
Setpoint 1
Setpoint 2
Digital Setpoint Shift (optional)
Outside Temperature (optional)
Pre-definition of External
Sepoints (optional)
Multiple Analog Inputs
Mod Bus Communications
Manual Overrive
"AUTO TUNE" Optimization
Display Value Range*
SP1 145-240
SP2 145-240
dSP 145-240
TA Consult Factory
SP.E Consult Factory
70
Factory Setting User Setting
180
0
0
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