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Innovation - Edge [i] Installation, Operation, Maintenance Manual
CHAPTER 2
– INSTALLATION
OMM-0143_A
• GF
-216
•
9/6/2019
Technical Support
•
(800) 526-0288
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Mon-Fri, 8 am - 5 pm EST Page 21 of 170
2.7 INTERNAL RECIRCULATION LOOP
The internal Recirculation Loop Assembly is located inside the unit enclosure at the rear of the
unit. In order to access this assembly, the right-rear panel must be removed, as shown in Figure
2.7.
This assembly contains a recirculation pump that connects the upper hot water outlet to the
lower cold-water inlet to
the unit’s heat exchanger. The purpose of this loop is to provide feed-
forward (FFWD) temperature control by mixing a portion of the hot water outlet with the cold-
water inlet to the unit. Temperature sensors located in the hot water outlet and cold-water inlet
provide temperature data to the Edge Controller. The Controller utilizes this data to modulate
the fire rate (Air/Fuel Valve position) to precisely maintain the hot water outlet temperature at
the selected setpoint temperature.
REAR VIEW
– REAR PANEL & EXHAUST VENT REMOVED
Figure 2.7. Recirculation Loop
RECIRCULATION
LOOP PIPING
HOT WATER OUTLET
2” NPT
P&T VALVE
RECIRCULATION
PUMP
COLD WATER INLET
2” NPT
LOWER DRAIN VALVE
HEAT EXCHANGER
FUEL INLET
NATURAL GAS, 1.5
” NPT