Navien NCB-190/060H, Installation & Operation Manual

Page: 39 / 145

39 Installing the System Piping
3.6.9 External Recirculation with HotButton and Dedicated Return Line (HotButton,
Aquastat)
External Recirculation Mode
To use the aquastat mode, install an aquastat to the DHW pipe line and connect to the CNC6 terminal on the PCB.
(Refer to “3.7.4 Wiring Diagram - Zone Pump System with DHW Recirculation” on page 43 for details.)
CAUTION
The aquastat temperature must be set lower than the NCB-H boiler DHW set temperature.
Note
Combi pre-heat is the default mode for DHW recirculation. To select external recirculation, refer to
the combi pre-heat and external recirculation sections in “11.5.3 Setting the DHW Operation” on page
108 for details.
N
A/H
DHW
PR I
L
N
L
N
L
N
L
N
L
Z3
Z2
Z1
SUPPLY
TEMPERATURE SENSOR
RETURN OUTDOOR T/S_ZONE3
R W C
T/S_ZONE2
R W C
T/S_ZONE1
R W C
AC24VN
AC24VL
lLWCO
R
W
C
T/S_Re
cir
COM
NO
NC
ZONE
_V /V
3
COM
NO
NC
ZONE
_V
/V2
COM
NO
NC
ZONE
_V
/V 1
N
A/H
DHW
PRI
L
N
L
N
L
N
L
N
L
Z3
Z2
Z1
SUPPLY
TEMPERATURE SENSOR
RETURN OUTDOOR T/S_ZONE3
R
W
C
T/S_ZONE2
R
W
C
T/S_ZONE1
R
W
C
AC24VN
AC24VL
lLWCO
R
W
C
T/S_Recir
COM
NO
NC
ZONE_V/V3
COM
2
1
Aquastat
* Recirculation
Pump
Check Valve
Aquastat
Check Valve
Wired Push
Button
Wired Push
Button
Expansion
Tank
DHW Supply
Return Water
Recirculation
Pump
(max. 2.5A)
Wired Push
Button
City
Water
Supply
* A Taco 008-BC6 or Grundfos 15-42 BUC7 (or equivalent) circulation pump is recommended for use with the NCB-H boiler and
DHW recirculation systems.
* When using the external recirculation mode, observe the following maximum recirculation pipe lengths including fittings ( 3 /
4
”
pipe is recommended). Lengths in excess of these limits will require a larger recirculation pump.
Maximum Equivalent Copper Pipe Lengths
Pipe Diameter
1
/
2
"
3
/
4
"
Maximum Pipe Length 100 ft (30 m) 400 ft (120 m)
Note
●
To use HotButton mode, install a HotButton Push Button(s) and recirculation pump, but not an
aquastat (
➊
).
●
To use Aquastat mode, install an aquastat and recirculation pump, but not a HotButton (
➋
).
●
The HotButton push buttons and wall plates are not included with the boiler, but are available for
purchase.