4
F.
Install Electric Wiring
in accordance with
NATIONAL ELECTRICAL CODE and Local
Regulations. The Burnham “CARE-FREE” Electric
Boilers may be used with 208 and 240 volt, 60 cycle,
single phase power and one 3 wire power supply. Since
the heaters are rated at 240 volts, however, any input
voltage less than this affects boiler capacity, see Figure
3.
To remove Front Door for access to terminal blocks and
controls:
1. CAUTION – make sure Electrical Service to Boiler
is disconnected.
2. Remove retaining screw at top of door.
3. Lower Door as far as possible, then push forward
until Hinge Pins in lower corners slide out of the
slots.
4. Raise one side of Door until Door will clear opening
– pull forward for removal.
Repeat above in reverse for replacing Door.
Provisions are provided in the right side of the boiler
jacket for power input, circulator, and thermostat
wiring, see Figure 1.
The power input legs are connected to the L1 and
L2 terminals on the terminal board on the control
compartment of the boiler. The neutral leg is connected
to the terminal marked N. Minimum recommended
wire sizes are shown in Figure 1. A separate grounding
conductor of at least #6AWG copper must be run to the
fi eld grounding lug on the control panel.
The Circulator is to be connected from its housing to
the terminals marked N and M on the Main Terminal
Block using Flexible Conduit, see Figures 2 and 4.
If the “QUICK CONNECT CIRCULATOR-PAK”
is ordered as Optional Equipment from the Boiler
Manufacturer, the Flexible Conduit for connecting the
circulator will be furnished.
G.
A Prewired Low Voltage Control System
is furnished
with every “CARE-FREE” boiler.
1. All controls are furnished in a compartment at the
front of the boiler for easy accessibility. In addition
to the Transformer used to power the system, are
the following: Circulator Relay, Heating Element
Sequencers (one per Heating Element), Dual High
Limit Control, Circulator Operation Selector Switch,
Circulator Fuse and Heating Element Relays.
2. If the Circulator Fuse is blown, power is interrupted
to the Transformer and hence, the control system
de-energized. This action prevents the Heating
Elements from coming on while the Circulator is
inoperative.
A Circulator Operation Selector Switch provides for
either Continuous or Intermittent Circulator operation.
With the switch in the “CONT.” position the Circulator
Delay Control will be bypassed and the Circulator will
operate continuously. The room Thermostat regulates
only the operation of the Heating Elements in the boiler.
With the Circulator Switch in the “INT.” position, the
Thermostat will operate both the Circulator and the
Heating Elements. Timing and wiring of the bimetal
heaters in the Circulator Relay and Sequencers assures
Circulator operation before and after Heating Elements
are energized and de-energized, respectively. The
Sequencers permit only one Heating Element at a time
(from bottom to top) to be energized thus preventing
a sudden inrush of electrical current. More detailed
operation is described in subsequent pages.
Wiring of a one zone system is shown in Figure 4.
Figures 5 and 6 show wiring for zoned systems, the
former when Zone Valves are used and the latter when
multiple Circulators are used.
Figure 3: Boiler Capacity at Various Voltages
