Bobcat Models B-120A and B-200A
43
APPENDIX A
Thermostat Heat Anticipator Settings
Fixed anticipator thermostats are not adjustable.
Adjustable anticipator thermostats, depending on thermostat
model, may be adjustable from a .18 to a .9 setting by mov-
ing a pointer on the anticipator.
The higher the anticipator setting (towards .9) the longer it
will take for the thermostat to respond to a change in room
temperature. Too high a setting and the boiler will be slow to
respond to a temperature change in the room. This can
cause the room temperature to drop to an uncomfortable
level before the boiler starts. This may generate homeowner
complaints.
The lower the anticipator setting (toward .18) the faster the
thermostat will respond to a change in room temperature.
Too low a setting and the boiler will short cycle. Boiler short
cycling will cause unnecessary wear on the equipment and
in the case of oil boilers it can lead to poor combustion and
more frequent cleaning of the combustion area.
It is important to understand what the thermostat is control-
ling and then determine the amp rating of that relay, gas
valve, zone valve or control. This information is usually
stamped somewhere on the component. A properly set
anticipator will allow the system to operate at its maximum
effectiveness.
Investigations of boilers which were installed in hard water
areas, revealed that mineral deposits had accumulated at the
bottom of the heat exchanger. In addition, sludge, scale and
other solid contaminants were present in boilers installed in
older systems or where the water was supplied from a well.
This accumulation creates an insulating layer that drastically
affects boiler efficiency by reducing the transmission of heat
through this primary transfer surface and causes extreme
metal temperatures that eventually crack the heat
exchanger.
RECOMMENDATIONS:
On all installations in hard water areas:
1. The system should be thoroughly inspected for leaks which
must be repaired however minor they may be.
2. The initial water charge of the system must be treated to
reduce its hardness to an acceptable level.
3. Where a continuous fresh supply of hard water is fed to the
system as with process or steam boilers, it is essential that:
a) The feed water is treated to reduce the level of hardness
to a point where no significant deposition occurs in the
boiler.
OR
b) The treated boiler water circulates through a closed circuit
heat exchanger which in turn will heat the distribution sys-
tem water.
In addition to the aforementioned, older systems and those
supplied from wells may require that a filter or strainer be
incorporated in the circuit at some point on the return line
closest to the boiler. Suitable water treatment filters are com-
mercially available for this purpose.
NOTE: DOMESTIC TANKLESS HOT WATER COILS ARE
HIGHLY SUSCEPTIBLE TO THIS CONTAMINATION
THE TERMS OF THE BOILER WARRANTY WILL NOT APPLY
TO FAILURES ENCOUNTERED UNDER THESE
CIRCUMSTANCES.
WE STRONGLY RECOMMEND THAT YOU CONVEY THIS
VITAL INFORMATION TO ALL PARTIES CONCERNED.
APPENDIX B
Accumulation of Foreign Deposits in Heat Exchanger
(4 Seiten)
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