23
LP- 428 REV. 9.2.14
Figure 8 – Cascade Multiple Boilers – Indirect Priority on One
FIGURE NOTES:
1. This drawing is meant to demonstrate system piping concept only.
2. A mixing valve is recommended if the DHW temperature is set above the factory setting of 119
o
F.
3. Install a minimum of 12 diameters of straight pipe upstream of all circulators.
4. Install a minimum of 6 diameters of straight pipe up and downstream of all closely spaced tees.
5. Piping shown is Primary/Secondary.
6. The minimum pipe size for connecting an HTP indirect fired water heater is 1”.
7. The minimum pipe size for connecting a Mod Con boiler is 3” for both the 1000 and 1700 models. See Multiple Boiler Manifold Piping chart, Figure 6
in this manual, when sizing and installing a multiple boiler system.
8. System flow (Secondary Loop) must be greater than the boiler’s Primary Loop flow.
9. Installations must comply with all local codes.
10. In Massachusetts, a vacuum relief valve must be installed on the cold water line per 248 CMR.
11. System sensor must be placed as shown in drawing.