PART 5: BOILER PIPING (CONTINUED)
Upon completion, make sure that the fill valve is
in the automatic position and each zone balance
and purge or shut off is in an open position and
zone valves are positioned for automatic opera-
tion.
1. Glycol in hydronic applications which is
specially formulated for this purpose includes
inhibitors that prevent the glycol from attacking
metallic system components. Make certain that
the system fluid is checked for the correct
glycol concentration and inhibitor level.
2. The glycol solution should be tested at least
once a year and as recommended by the
glycol manufacturer.
3. Anti-freeze solutions expand more than
water. For example a 50% by volume solution
expands 4.8% in volume for a temperature
increase from 32° F to 180° F, while water
expands 3% with the same temperature rise.
Allowances must be made for this expansion
in the system design.
4. A 30% mixture of glycol will result in a BTU
output loss of 15% with a 5% increase in
head against the system circulator.
5. A 50% mixture of glycol will result in a BTU
output loss of 30% with a 50% increase in
head against the system circulator.
J. ZONING WITH ZONE VALVES
1. Connect the boiler to the system as shown in
Piping Details when zoning with zone valves.
The primary/secondary piping shown
ensures the boiler loop will have sufficient
flow. It also avoids applying the high head of
the boiler circulator to the zone valves.
2. Connect DHW (domestic hot water) piping to
indirect storage water heater as shown.
K. ZONING WITH CIRCULATORS
1. Connect the boiler to the system when using
circulator zoning as shown in Piping Details
when zoning with circulators. NOTE: The
boiler circulator cannot be used for a zone. It
must supply only the boiler loop.
2. Install a separate circulator for each zone.
3. Connect DHW (domestic hot water) piping to
indirect storage water heater as shown in
Piping Details.
L. MULTIPLE BOILERS
1. Connect multiple boilers as shown in Piping
Details.
2. All piping shown is reverse return to assure
balanced flow throughout the connected
boilers.
3. Each connected boiler must have its own
circulator pump to assure adequate flow.
4. Connect DHW (domestic hot water) piping to
indirect storage water heater as shown in
Piping Details.
5. The system flow (secondary loop) must be
greater than the boiler’s primary loop flow.
GAS-FIRED BOILER Boiler Manual
23
n
CAUTION
For installation that incorporates standing iron
radiation and systems with manual vents at the
high points. Follow previous section and
starting with the nearest manual air vent, open
vent until water flows out, then close vent.
Repeat procedure, working your way toward
furthest air vent. It may be necessary to install
a basket strainer in an older system where
larger amounts of sediment may be present.
Annual cleaning of the strainer may be
necessary.
n
WARNING
Use only inhibited propylene glycol solutions
which are specially formulated for hydronic
systems. Ethylene glycol is toxic and can attack
gaskets and seals used in hydronic systems.
Glycol mixtures should not exceed 50%.
n
CAUTION
It is highly recommended that you carefully
follow the glycol manufacturer’s recommended
concentrations, expansion requirements and
maintenance recommendations (pH additive
breakdown, inhibitor reduction, etc.). You must
carefully figure the additional friction loss in the
system as well as the reduction in heat transfer
co-efficients.
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