CLEAN BURN CB-200-CTB, Руководство оператора

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Coil Tube Boiler Operator's Manual: Models CB-200-CTB, CB-350-CTB, and CB-500-CTB
10-2
CTB System Function and Configuration
Water Flow and Temperature
The Clean Burn Coil Tube Boiler design requires continuous water flow through the boiler heat
exchanger to ensure proper system operation. The boiler circulator must be capable of developing
sufficient (head) pressure to overcome the resistance of the boiler plus the circulating system at the
required GPM. If the water flow through the boiler is too low, the flow switch will not allow the
burner to operate. (Refer to Appendix A, as needed, for CTB system specifications.)
Heating systems using zone valves, zone pumps, or three-way valves may experience reduced water
flow through the boiler. This condition can cause excessive water temperature rise and unstable boiler
operation. The normal temperature rise across the boiler is 20
o
F . Minimum operating temperature for the
CTB is 180 o F . To avoid condensation, the return water temperature should not fall below 140 o F .
Boiler Mixing Valve 140
o
F
Provided with the boiler plumbing is a 140
o
F Mixing Valve set up to blend cold water return from the system to
maintain a proper temperature (above 140
o
F) for the “Non-condensing” design of the CTB. For optimal boiler
operation with the Mixing Valve, and when burning used oils, it is recommended to run the boiler “hot” (180 o F
to 200
o
F). Therefore the operating aquastat setting should be no less than 180
o
F. The high limit
aquastat factory recommended setting is 220-240
o
F.
The 140
o
F Mixing Valve must be installed according to Figure 10B or 10C and must be as close as possible
to the suction side of the boiler circulator . This allows the by-pass loop to function properly. When starting
the boiler from cold (room temperature) the boiler water temperature will be able to come up above 140
o
F
within 5 to 7 minutes (variance caused by unit settings and type of fuel). As the boiler temperature rises above
160
o
F the Mixing Valve will modulate and allow more system return water to be mixed into the boiler therefore
supplying more hot water to the zones.
System Pressure
The Clean Burn CTB is designed to operate in closed, pressurized hydronic systems. Certain levels of pressure
are required for proper system operation--
a minimum of 12 PSI should be maintained on the system
where the boiler supply water temperature is 200
o
F or less. If a higher working pressure is required,
contact the Clean Burn Service Department for proper pressure requirements.
Sample System Configuration: Primary/Secondary Pumping System
A sample hydronic system setup using Clean Burn Coil Tube Boilers is shown in Figure 10A. This system, a
Primary/Secondary Pumping System, allows for many special hydronic requirements (e.g. water return
temperatures below the normal 140 o F , variable flow zones, multiple zones, multi-temperature systems, and/or
multiple boilers) and provides maximum flexibility while maintaining optimal system functioning. A critical
advantage of this type of system is that it dramatically reduces the danger of thermal shock to the
boiler.