Pellet particulars

The Glitch:

Figure 1 shows a piping layout that was used to retrofit a pellet-fired boiler to an existing 4-zone heating system supplied by an oil-fired boiler. The pellet boiler is protected against sustained flue gas condensation by a “loading unit,” which combines a circulator with a thermostatic mixing valve. The distribution system is connected to the retrofitted pellet boiler piping using a pair of closely spaced tees. Can you spot several errors in this piping layout and propose modifications that would correct them? 

Are you an ace troubleshooter?

Within the pages of this magazine, PM’s Hydronics Editor John Siegenthaler, P.E., will pose a question to you, our readers, to review a system’s schematic layout and discover its faults, flaws and defects. Discover archived “The Glitch & The Fix” exercises at its radiant-focused website, www.radiantandhydronics.com. Good luck!