Westinghouse WBRC 140 Series Installation, Start-Up, Maintenance, Parts, Warranty page 22

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Figure 11 - Primary / Secondary Piping with Zone Valves - DHW Priority and Outdoor Reset
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 and CH piping should be 1" in diameter.
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/Secondary. 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. In a valve-based system, each heating zone has a zone valve which opens when that zone calls for heat. Each zone thermostat is wired to its
corresponding zone valve. Contacts in the zone valves provide a signal to the boiler to operate when there is a call for heat.
10. Unit is equipped with built-in primary pump for the heating loop. This pump is sized to insure proper flow rate through the boiler
heat exchanger and related piping. On long pipe runs, it is recommended to keep the pump at maximum speed (setting 3). DO NOT lower it
from the factory default.
11. NOTE: DO NOT INSTALL a flow check or a pump with flow check on the return line of the primary loop going to the boiler. This will isolate
the boiler from the expansion tank, causing pressure to build up in the unit and the Pressure Relief Valve to discharge.
whl-648 Rev. 001 Rel. 003 Date 10.8.19