LP-293 Rev. 9.24.15
19
• Glycol in hydronic applications should include inhibitors
that prevent the glycol from attacking metallic system
components. Make certain that the system uid is
checked for the correct glycol concentration and inhibitor
level.
• The glycol solution should be tested at least once a year
or as recommended by the glycol manufacturer.
• 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
o
F to 180
o
F,
while water expands 3% over the same temperature rise.
Allowances must be made in system design for expansion.
• A 30% mixture of glycol will result in a BTU output loss
of 15% with a 5% increase in head against the system
circulator.
• A 50% mixture of glycol will result in a BTU output loss
of 30% with a 50% increase in head against the system
circulator.
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 calculate the additional friction loss in the system as
well as the reduction in heat transfer coecients.
L. Zoning with Zone Valves
1. When zoning with zone valves, connect the boiler to the
system as shown in Applications. The primary/secondary
piping shown ensures the boiler loop will have sucient ow.
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 in Applications.
M. Zoning with Circulators
1. When using circulator zoning, connect the boiler to the
system as shown in Applications. NOTE: The boiler circulator
cannot be used for a zone. It must only supply 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 Applications.
N. Multiple Boilers
1. Connect multiple boilers as shown in Applications.
2. All piping shown is reverse return to assure balanced ow
throughout the connected boilers.
3. Each connected boiler must have its own circulator pump to
assure adequate ow.
4. Connect DHW (domestic hot water) piping to indirect
storage water heater as shown in Applications.
5. The system ow (secondary loop) must be greater than the
boiler’s primary loop ow.
Water temperature above 140
o
F requires the circulator
pump to run continuously and water hardness between 5
and 7 grains. Hardness above 7 grains will damage the heat
exchanger and shorten the service life of the boiler.
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