LP-428 Rev. 6.6.16
15
2. Size the piping and components in the space heating system
using recognized design methods.
F. Hydronic Piping with Circulators, Zone Valves, and
Multiple Boilers
The boiler is designed to function in a closed loop hydronic
system. The included temperature and pressure gauge allows
the user to monitor system pressure and outlet temperature
from the boiler. It is important to note that the boiler has a
minimal amount of pressure drop that must be calculated
when sizing the circulators. Each boiler installation must have
an air elimination device that will remove air from the system.
Install the boiler so the gas ignition system components
are protected from water (dripping, spraying, etc.). Allow
clearance for basic service of the boiler circulator, valves, and
other components. Observe minimum 1” clearance around all
uninsulated hot water pipes when openings around pipes are
not protected by non-combustible materials.
On a boiler installed above radiation level, some states and
local codes require a low water cut o device. This is provided
standard on the ModCon boiler. Check with local codes for
additional requirements. If the boiler supplies hot water to
heating coils in air handler units, ow 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
specically formulated for this purpose. This glycol must
include inhibitors that will prevent it from attacking metallic
system components. Make certain that the system uid is
checked for the correct glycol concentration and inhibitor
level. The system should be tested at least once a year and
as recommended 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 glycol
solution expands 4.8% in volume for the temperature increase
from 32
o
F to 180
o
F, while water expands 3% over the same
temperature rise.
Never use dielectric unions or galvanized steel ttings when
connecting to a stainless steel storage tank or boiler. Failure
to follow this instruction can lead to premature failure of the
boiler system. Such failures ARE NOT covered by warranty.
The boiler should not be operated as a potable hot water
heater. The boiler should not be used as a direct hot water
heating device.
Table 3 - Minimum Flow Rates
Minimum Boiler Flow Rates
Model Minimum Flow (GPM)
MODCON1000 66
MODCON1700 109
In addition, the boiler heat exchanger has a minimum total
water volume that must be taken into account when sizing
the circulator. Minimum boiler ow rates are listed in the table
below.
G. Circulator Sizing
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