15
A system bypass should be installed as shown in fig. 10 to prevent
boiler circulation starvation when the system zones call for reduced
flow.
This bypass may also be used with multiple boilers manifolded for
reverse-return flow. The system bypass would be installed from
boiler outlet to suction side of pump.
Standard Dura-Max models are factory equipped for Single Stage
Firing only.
Dura-Max models may be factory equipped for Dual Stage Firing.
The gas valve automatically steps gas input down from full input
to approximately 50% total input. System conditions will then
determine if boiler will shut down or if unit will return smoothly to
full input.
Dura-Max models may also be equipped with modulation which
automatically adjusts the boiler output to match the system heat
loss and variations of system water flow. Minimum firing rate is 50%.
INSTALLATION AS BOILER REPLACEMENT
Installation as boiler replacement on an old system with large
water volume may result in condensation within the boiler on cold
starts. This condensing of water vapor in the combustion area
can be prevented if a portion of the system water flow is diverted
past the boiler to cause an increase in boiler temperature rise.
FIGURE 10
DB INSTALLATION
INSTALL IN ACCORDANCE WITH
ALL LOCAL CODES.
WHEN BLOW DOWN VALVE IS
REQUIRED, INSTALL IN PLACE OF
THE DRAIN VALVE SHOWN.
