51
Installing the System Piping
With 24VAC connections
N
A/
H
DH
W
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_Reci
r
COM
NO
NC
ZO
N
E_V/V
3
COM
NO
NC
ZO
N
E_V/V
2
COM
NO
NC
ZO
N
E_V/V
1
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
NO
NC
ZONE_V/V2
COM
NO
NC
ZONE_V/V1
Recirculation Timer,
Aquastat,
or HotButton
Push Button
24 VAC N
Thermostat Input
24 VAC L
Thermostat 3
24 VAC N
Thermostat Input
24 VAC L
Thermostat 2
24 VAC N
Thermostat Input
24 VAC L
Thermostat 1
N
A/H
DHW
PRI
L
N
L
N
L
N
L
N
L
Z3
Z2
Z1
System pump
(max. 2.5 A)
Recirculation pump
(max. 2.5 A)
Pump Ground
Zone valve 1
(max. 1A)
Zone valve 2
(max. 1A)
Zone valve 3
(max. 1A)
Note
●
NO (Normal Open): Power is supplied when the zone valve is operating, and power turns off when
the zone valve stops.
●
NC (Normal Close): Power is supplied when the zone valve stops, and power turns off when the
zone valve is operating.
●
COM: 24 V AC COMMON
●
The boiler has an internal 24V transformer that is rated for 75VA. This transformer provides power
to the zone valve, low water cut-off (LWCO) and thermostat terminals.
●
If the total power consumption of all 3 zone valves exceeds 70VA, an external zone valve controller
must be used.
Summary of Contents for NFC-250/175H
Page 67: ...67 Venting for Combustion Air WARNING The vent installation detector Detectable Undetectable...
Page 149: ...Memo...
Page 150: ......