mr
.
steam
®
C U S E R I E S
Installation, Operating & Maintenance Manual
INSTRUCTIONS FOR ELEMENT REPLACEMENT
READ INSTRUCTIONS COMPLETELY BEFORE STARTING WORK
Models
CU360
-
CU1400
use
probes
for
liquid
level
sensing
and
control.
Model
CU2000
and
higher
use
McDonnell-Miller
MM
150.
1.
Disconnect boiler from electric power supply at main safety switch or fuse panel.
Then turn boiler switch to “OFF" position.
2.
Close water supply valve on incoming water supply line.
Drain boiler completely of water.
3.
Open boiler door to access heating element.
4.
Disconnect wire (electric) leads connecting element to main power
system of boiler. Again, note wire connections to facilitate re-assembly.
Proceed to remove and discard (6) bolts from flange.
The wire connections to facilitate re-assembly (see wiring schematic).
Remove and discard six (5/16"-18) bolts from flange. Do not reuse these bolts.
5.
Thoroughly clean boiler flange of all foreign material. Be certain no part of old
gasket remains on flange.
6.
Proceed to install element flange assembly with gasket between boiler flange
and element flange. In doing this, be careful to align flange holes so element wire
connection terminals on element assembly are in line with previously disconnected
wire leads to facilitate easy connections.
Observe markings on element flange. Install element marking
“TOP” on top.
7.
Use only new element flange bolts. Tighten all (6) element flange bolts to a torque
value of 22 lb-ft each (see illustration).
8.
Connect all wires to the terminals. Tighten all element terminals to a torque value
of 20 lb-in each (see illustration). Make sure all wires are clean and bright to
assure good electrical contact.
9.
Check that the wires are correctly connected to the contactor terminals and are
tightened to a torque listed on the contactor (ensure each nut holding the bus
bars in place are torqued to 20 lb-in). Make sure all wires are clean and bright
to assure good electrical contact.
10.
Open water valve to allow water supply to reach boiler feed mechanism.
11.
As boiler automatically refills, observe the new flange assembly for possible
leaks. If water is noticed, the bolts must be re-tightened. Before doing this, turn
the boiler off at the main fuse safety switch.
12.
When boiler reaches working pressure, check flange assembly again for leaks.
Avoid use of chemical cleaning compounds.
Follow maintenance instructions provided with the boiler.
Torque Values:
Element Flange Bolts: 22 lb-ft
Element Terminals: 20 lb-in
Contactor Terminals: See Torque Chart
For Illustrative Purposes Only.
Power wiring shown in approxi-
mate factory-installed location
Torque
Wrench
Torque Wrench
Torque
Wrench
Boiler with
McDonnell Miller
1
1
⁄
2
”
1” Steam Equalizing Pipe
Pump and Low Water Control
Normal Boiler Water Line
CutOff
Level
is
Arrow
Mark
Blowdown
Valve
1”
Water
Equalizing
Pipe
TORQUE VALUES
Element Flange Bolts
22 lb-ft
Element Terminals
20 lb-in
Contactor Terminals: Tighten to torque
specified on contactor.
Before
Installing
your
new
elements
be
sure
McDonnell
Miller
low
water
cutoff
and
aux.
low
water
cutoff
(if
supplied)
is
operating
properly.
The
float
chamber
and
lower
equalizer
column
of
the
MM
control
must
be
completely
clear
of
sludge
or
other
foreign
matter.
Failure
to
do
this
may
cause
the
immediate
burn-out
of
the
new
elements.
If
the
unit
is
probe
equipped,
check
condition
of
the
probes
and
isolator.
All
elements
are
thoroughly
checked
before
shipment.
The
manu-
facturer
cannot
be
responsible
for
burn-outs
caused
by
a
faulty
low
water
cutoff.
The
lower
equalizer
column
can
best
be
examined
by
breaking
the
unions
on
either
side
and
then
visually
and
manually
examining
the
piping
with
your
finger
or
probes
to
see
if
it
is
clear
and
clean.
36
