Electro Industries Mini-Boiler EMB-S-1, Installation & Operating Instructions Manual

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03/12/2019
8
BI309
OPERATIONAL TIPS
1. Indicator lights – there is a set of four indicator lights on the front cover. Figure 1 is a reproduction of the
front decal giving definition and information for using these indicator lights.
2. Boiler Power green LED indicates 24-volt is present on the control board and is continuous on. Off could
mean no 240/208-volt power, open manual reset (vessel top), open fuse, or bad transformer. Also indicates
supply sensor condition (solid = good, pulse = faulty).
3. 240/208-volt element power current flow can only be measured when the external operating thermostat is
calling for heat. There is a 30-second delay before stage 1 turns on, this allows the pump to circulate and
sample temperature. Stage 2 will depend upon the temperature differential at the sensor in the supply pipe,
see page 9 sequence (assumes off-peak mode).
4. The operating thermostat heat call can be verified by the red LED marked Thermostat Call located on front
cover.
5. Electric Mode yellow LED is on when the boiler is not being load controlled (blue wires closed).
6. The 190°F Auto Reset Limit red LED is on when the vessel top hi-limit switch is open.
7. Via a small pin jumper arrangement on the control board, the circulator pump can
be a direct function of the “W” input
or interrupted by the load control device (even
though there is a W input). This diagram illustrates this pin jumper arrangement.
This unit is factory setup in the “W” position meaning the pump will always run as
a direct function of “R” to “W” operating thermostat. By simply moving this black
2-position jumper to the “L” the pump will be turned off during load control
interrupt.
8. At outlet temperatures of approximately 120

F, the maximum system pressure should be approximately 18
PSI (124 kPa). If the PSI (or kPa) increase from cold water to operating hot water is more than
approximately 3 to 4 PSI (20.6 to 27.5 kPa), the expansion tank is too small, or there is air in the system.
9. At the top of the vessel is a manual reset, 205° F, primary hi-limit. This is behind the upper control board
cover, at the top of the vessel. At the end of the two red/blk wires there is a small red stem between the wire
tabs. This is the reset button.
10. Check for water leaks and repair as required.
11. If flow seems to be a concern, determine both inlet and outlet water temperature and apply GPM (L/min)
formula detailed in previous section “Information/Water Flow Calculations”.
AQUASTAT OPERATION
Determine from floor tubing supplier design outline the desired floor temperature. Typically this relates to
floor covering and tube placement design. Set the aquastat set point for desired warm water outlet.
The front temperature set point is selected by a small screwdriver dial switch.