LP-293 Rev. 9.24.15
20
NOTES:
1. This drawing is meant to show system piping concept only.
2. A mixing valve is recommended if the DHW temperature is set above 119
o
F.
3. Install a minimum of 12 diameters of straight pipe upstream of all circulators.
4. Piping shown is Primary/Secondary.
5. System ow (secondary loop) should be greater than the boiler primary loop ow. In all cases, the boiler primary loop ow rate must be
maintained above the minimum ow rates published in this manual.
6. Installations must comply with all local codes.
7. In Massachusetts, a vacuum relief valve must be installed in the cold water line per 248 CMR.
The piping will not support the weight of the circulators. Refer to the circulator manufacturer’s instructions to properly support
the circulator. Failure to comply with these instructions could result in property damage, severe personal injury, or death.
Figure 7 - Boiler with Indirect Priority
Primary
Loop
Secondary
Circuit
O. Applications*
*NOTE: Systems shown are primary/secondary piping systems. These recommended systems have a primary (boiler) loop, and
secondary circuits for heating. The primary loop and secondary circuits have separate circulators. The use of other near boiler
piping congurations could result in improper ow rates, leading to inadvertent boiler high limit shutdowns and poor system
performance.
NOTE: In piping applications utilizing a single zone, it is recommended that the installer use ow / check valves with weighted
seats at or near the appliance to prevent gravity circulation.
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