40
WHL-032 REV. 6.2.16
Figure 26
– Cascaded System - Zoning with Pumps and Indirect Fired Water Heater – Primary/Secondary Shown
NOTES:
1. This drawing is meant to show system piping concept only. Installer is responsible for all equipment and detailing required by local
codes.
2. All closely spaced tees shall be within 4 pipe diameters center to center spacing.
3. A minimum of 6 pipe diameters of straight pipe shall be installed upstream and downstream of all closely spaced tees.
4. The
minimum
pipe size of DHW piping should be ¾” diameter. See Table 16 for
minimum
CH pipe sizing.
5. Circulators are shown with isolation flanges. The alternative is standard flanges with full port ball valves. Purge valves can be used
with circulator flanges as an alternative.
6. Piping shown is Primary/S
econdary. System flow (secondary loop) must be greater than the boiler’s primary loop flow.
7. Install a minimum of 12 diameters of straight pipe upstream of all circulators.
8.
VERY IMPORTANT
– Minimum flow rates outlined in this manual must be maintained through the heat exchanger to minimize short
cycling.
9. Each heating zone of a pump-based system has its own circulator with turns on when a zone thermostat calls for heat.
10. If Boiler Pump on the return line does not have an internal flow check, install a check valve on the return line to the boiler.
