Midco Unipower G-Series - Manual (Page 3)

I Ventilation
Continued
with a barometric draft control, 1 1 / 2 square feet when equipped with a draft hood. If the ventilation
opening is screened, it should be of 1 1 /
4
" mesh. The opening should be located at least six feet over
ground level to prevent accidental obstruction. If a direct opening to the outside air is not available, an
amply sized air duct can be run to the nearest outside air source or if practical, open stairwells or
building corridors connecting to an outside wall having a ventilating opening can be used for this
purpose, provided that no possibility of accidental closure exists.
■ ■ While the spark ignition pilot system performs successfully under moderate or momentary back draft
conditions, it is not intended for operation under sustained reverse draft, for example, in a building with
large ventilating fans but with insufficient make-up air. Even if burner operation is successful under these
conditions, they must be corrected to prevent the hazard of drawing flue gases into the building.
Consult your local gas company when doubt exists concerning boiler room ventilation.
■ ■ The heating system, both the gas utilization equipment and the distribution system, should be in
good repair and sufficient to properly heat the building. It should be determined if any serious faults are
present that would cause excessive fuel consumption, unsafe operation or improper heating, and
measures taken to correct them.
■ ■ After the grates and grate operating parts have been removed from the firebox, the boiler interior
should be thoroughly cleaned, removing all adhering dirt, tars, scale and soot. All joints should be
cemented to prevent excess air infiltration into the boiler. Clean out doors should be checked for close
fit, and sealed with furnace cement if they fit poorly.
■ ■ Firing door catches should be filed off or otherwise arranged so that the door will open easily to
relieve pressure. No positive catches should be used. The use of a spring-type door holder is
r e c o m m e n d e d .
■ ■ The Unipower gas burner is designed for "in-shot" firing. It can be fired into the ashpit of a boiler
designed for solid fuels, or it can be fired into the primary heat exchanger of a boiler designed for liquid
or gaseous fuels. The ashpit installation requires a refractory lining.
■ ■ The combustion chamber serves to contain and promote combustion and to protect non-heat
exchange surfaces from direct flame contact. Built-up combustion chambers should be made of 2600°
insulating firebrick. As an alternative, a monolithic floor can be cast in place, using a high temperature
(2400°) light weight insulating refractory. Check with your supplier to determine the thickness which will
yield equivalent insulating qualities.
Figure 1: Typical Floor and Wall Construction
For 225,000 BTU Per Square Foot (Standard)
Figure 2: Typical Floor and Wall Construction
For 275,000 BTU Per Square Foot
3
II Gas Utilization
Equipment
III Combustion Chamber