About the Boiler 37
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 lline and connnect to the CNC6 terminal on the PCB. (Refer to "3.7.4 Wiring
Diagram - Zone Pump System with DHW Recirculation" on page 41 for details.)
CAUTION
The aquastat temperature must be set lower than the NFC boiler hot water 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 "11.3.4 Setting the DHW Operation" on page 90 for details.
N
A/H
DHW
PRI
L
N
L
N
L
N
L
N
L
Z3
Z2
Z1
AC24VN
AC24VL
lLWCO
R
W
C
T/S_DWH
R
W
C
R
W
C
T/S_CH_ZONE1
T/S_ZONE2
SUPPLY
TEMPERATURE SENSOR
RETURN
OUTDOOR
T/S_ZONE3
R
W
C
N
A/H
DHW
PRI
L
N
L
N
L
N
L
N
L
Z3
Z2
Z1
AC24VN
AC24VL
lLWCO
R
W
C
R
W
C
R
W
C
T/S_CH_ZONE1
T/S_ZONE2
SUPPLY
TEMPERATURE SENSOR
RETURN
OUTDOOR
T/S_ZONE3
R
W
C
T/S_Recir.P
2
1
Aquastat
* Recirculation Pump
Check Valve
Aquastat
Check Valve
Wired
HotButton
Wired
HotButton
Pump Ground
DHW Supply
Return Water
Recirculation
Pump
(max. 2.5A)
Wired
HotButton
City
Water
Supply
* A Taco 008-BC6 or Grundfos 15-42 BUC7 (or equivalent) circulation pump is recommended for use with the NFC 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 and recirculation pump, but not an aquastat (
➊
).
●
To use Aquastat mode, install an aquastat and recirculation pump, but not a HotButton (
➋
).
Summary of Contents for NFC-175
Page 122: ...Memo...
Page 123: ...Memo...