Xylem EPR IM Electric heater-circulator unit EPR (obsolete) - Manual (Page 24)

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Instruction manual Laing Electric heater circulator unit
www.lainginc.com
Electrical connection of the EPR for domestic hot water heating
Following two possibilities are described for the connection of the EPR. To
guarantee proper operation the exact function of the boiler control has to be
known.
During the summer boiler controls with domestic hot water priority circuit
control operate by detecting the domestic hot water heater temperature. If
the detected temperature falls below the desired temperature there are two
versions of operation:
The control starts the burner and the hot water heater feed pump at the
same time. If this is the case, it is easily possible to install the Electric heater-
circulator EPR as described below under “Control method 1”. No additional
sensor in the hot water heater is necessary.
The control first turns on the burner and activates the water heater feed
pump only when the temperature of the water heater is at least 1°F. Since
the burner is switched off during summer time, the control of the domestic hot
water heater is only possible with an additional sensor in the hot water heater.
In this case one has to follow the diagram described under “Control method
”.
For both control methods the additional printed circuit board Type EPRBW
will be needed when the Electric heater-circulator is used to heat the domestic
hot water. After removing the cover of the control box this circuit board has
to be connected to the terminals 5, 8, 13 and 14 of the main printed circuit
board.
Control method 1
The wiring has to be performed according to the wiring diagram shown be-
low, whereby the leads of the hot water heater feed pump loop through the
control of the Electric heater-circulator. The lead III of the pump coming from
the boiler will be connected to ground and phase at CS1. Lead II leading
to the pump will be connected to CS. In addition a control lead IV will be
connected to CS3, which prevents the boiler from turning on as long as the
electric heating is activated.
As long as the electric heating is switched off via the main switch the relay
on the additional printed circuit board is de-energized and the lead wire for
the hot water heater feed pump is properly connected. In addition the control
contact of this relay is closed for the burner, so that the boiler now takes care
of the heating of the domestic hot water. In this case the check valve of the
Electric-heater-circulator is closed and the check valve to the boiler is open
as long as the hot water heater feed pump is running.
As soon as the main switch of the Electric heater-circulator is turned on,