Specifications

LWLCWH COLUMBIA BOILER COMPANY REV. 13106
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APPENDICES
Recirculation
Whenever hot water is supplied for process to some distant point, the water in the connecting line will
cool, making it necessary to draw off the cool water before hot is obtained. In some applications
where lines are long and large, this could be a troublesome factor, but it can be readily corrected by
installing a circulator pump. A recirculation system generally requires a small line (1/2" is often ade-
quate) connected between the end of the hot supply header and the cold supply to the heater. A con-
ventional circulating pump, preferably bronze or stainless trimmed, when installed in this return line,
will effectively maintain hot water throughout the supply header. A swing check valve will prevent short
circuiting.
Twin Units and Tank Systems
If larger volumes of hot water are required beyond the range of the largest Columbia water heater, we
would suggest either using multiple units or combination tank systems. The combination tank system
consists of a galvanized storage tank of suitable capacity connected to the water heating coils in the
Columbia indirect water heater through a bronze or stainless trimmed circulating pump. The pump cir-
culates the water from the tank through the water heater and is controlled by an Aquastat located in
the lower part of the storage tank. A high head pump is recommended for this service. A needle valve
and a thermometer should be installed in the circulating line so that the rate of circulation can be
adjusted to match the capacity of the water heater