PART 5: BOILER PIPING (CONTINUED)
GAS-FIRED BOILER Boiler Manual
15
lows the user to monitor the system pressure and
outlet temperature from the Mod Con Boiler. It is
important to note that the Mod Con Boiler has a
minimal amount of pressure drop and must be cal-
culated when sizing the circulators. Each Mod Con
Boiler installation must have an Air Elimination de-
vice that will remove air from the system. Install the
Mod Con Boiler so the gas ignition system com-
ponents are protected from water (dripping, spray-
ing, etc.) allowing clearance for basic service of
boiler circulator, valves and other components.
Observe minimum 1” clearance around all un-in-
sulated hot water pipes when openings around
pipes are not protected by non-combustible ma-
terials. On a Mod Con Boiler installed above radia-
tion level, some states and local codes require a
low water cut off device which is standard on the
Mod Con boiler. Check with local codes for addi-
tional requirements. If the Mod Con Boiler supplies
hot water to heating coils in air handler units, flow
control valves or other devices must be installed to
prevent gravity circulation of boiler water in the
coils during the cooling cycle. Chilled Water
Medium must be piped in parallel with the boiler.
Freeze Protection for new or existing systems must
use glycol that is specifically formulated for this
purpose. It will include inhibitors that will prevent
the glycol from attacking the metallic system com-
ponents. Make certain that the system fluid is
checked for the correct glycol concentration and in-
hibitor level. The system should be tested at least
once a year and as recommend by the producer of
the glycol solution. Allowance should be made for
the expansion of the glycol solution in the system
piping. Example 50% by volume gycol solution ex-
pands 4.8% in volume for the temperature increase
from 32 F to 180 F, while water expands 3% with
the same temperature rise.
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