Electrical Connections; Access To Connection Block; Main Supply Connection - UTICA BOILERS MAHF-75 Installation, Operation And Maintenance Manual

! D AN GER
Elect rocut ion Hazard! HI GH VOLTAGE -
Connect ions in t erm inal block M1 are high
volt age ( 120V / 60Hz) . Before m aking
connect ions, verify appliance is disconnect ed
from power supply. Respect t he input polarit y
on t erm inal block M1: L ( LI NE) - N ( NEUTRAL) .
Failure t o follow t hese inst ruct ions WI LL result in
deat h or serious inj ury.
8 .3 Access To Connect ion Block
1.
Ensure t here is no line volt age at boiler.
2.
Lift and rem ove front cover. Rem ove screws ( 2)
from cover on j unct ion box locat ed on boiler's left
side. Rem ove j unct ion box cover.
3.
Guide cont roller or t herm ost at wire t hrough round
grom m et ( s) locat ed on t op panel of boiler.
4.
Tilt cont rol box forward by opening holding clip
locat ed on left side of cont rol housing.
5.
Expose M1 and M2 t erm inal blocks by rem oving
screw from plast ic cover on left . See Figure 8- 3.
6.
Rem ove plast ic from channel in plast ic cover. Run
wires t hrough new opening.
7.
Connect wires t o appropriat e t erm inals on
connect ion block.
8.
Tilt cont rol box back t o original posit ion. Ensure clip
on left side of cont rol box is fully engaged.
9.
Replace front cover and cover t o j unct ion box.
10.
Turn power t o boiler on.
Dry cont act end swit ches from various m anufact urers
can be at t ached t o boiler cont rol PCB.
8 .4 M a in Supply Connect ion
Main supply is connect ed t o t erm inal block M 1 which is
high volt age ( 120V / 60Hz) .
Fuses, 3.15 A, are incorporat ed in t he power supply
t erm inal block. To check or replace fuse pull out black
fuse carrier.
TERM I N AL BLOCK M 1
( L) = Live ( brown)
( N) = Neut ral ( light blue) .
= Ground ( yellow- green) .
( 1) ( 2) = cont act for 120V Room Therm ost at .
Place j um per back on t erm inals 1- 2 of boiler t erm inal
block M 1 if room t herm ost at is not used
8 - ELECTRI CAL CON N ECTI ON S
FI GURE 8 - 2 Term ina l Block Loca t ions
FI GURE 8 - 3 Term ina l Pla st ic Cover w it h Knock out s
TERM I N AL BLOCK M 2
Te r m in a ls 1 - 2 : Buss connect ion of Open Therm
Te r m in a l 3 : Not used on Com bi unit s
Te r m in a ls 3 - 4 : I ndirect st orage t ank sensor
connect ion for heat- only boilers
Te r m in a l 4 - 5 : Out door t em perat ure sensor
connect ion ( supplied as an accessory)
Te r m in a ls 6 - 7 - 8 : 24V room t herm ost at connect ion
Te r m in a ls 9 - 1 0 : 0 - 10V connect ion
4 3
Fuse Holders ( 2)
Rem ove
New Opening
240013503 REV A, [ 03/ 15/ 2022]