Retrotec USACE - Manual (Page 185)

Appendix D D55
D.4.1.20 Use of Dampers to Control Air Flows (Ineffi ciency)
Figure D95. Damper in boiler breeching for
control of fl ow of combustion gases through
boiler. Figure D94. Direct drive fan on boiler that
could be easily converted to variable-speed
drive.
In effi cient boiler operations, the combustion air is varied as fi ring rates and
other conditions change. Dampers placed in the combustion air duct or the
fl ue gas breeching are often the devices used to vary the fl ow. A more effi cient
method to vary the air would be to use variable-speed motors on the induced
draft and/or the forced draft fans (Figure D94). If dampers are found to be
used to vary combustion air fl ow, more effi cient variable-speed motors may
have an application (Figure D95).
D.4.1.21 Surface Temperature of Boiler, Pipes, or Other Hot
Surfaces Greater Than 51.7 °C (125 °F) (Waste)
Figure D96. Uninsulated hot heating pipe
poses a safety problem as well as a source of
energy waste.
Heating equipment and their distribution pipes need to be well insulated to
avoid wasting energy. Energy that is lost to the surrounding space due to poor
insulation means the boiler must work harder to supply heat to the systems that
need it (Figure D96). A proper amount of insulation would result in the tem-
perature of outer surfaces of the heating system components being no greater
than 51.7 °C (125 °F). This not only an energy-saving concern, but a safety
concern, to avoid skin burns. Surfaces warmer than this temperature should be
investigated for additional insulation.