Lochinvar Copper-Fin CW 495, Designer'S Manual

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LOW WATER
TEMPERATURE DELIVERY
A number of water heating applications may
require delivered water temperature in a
system below 140°F. Systems such as nursing
homes and hospitals would be examples of
this type of system.
A water heating system that will be operated
at less than 140°F
must use a mixing valve
on the outlet side of the storage tank in order
to ensure that the products of combustion do
not condense inside the combustion chamber
of the water heater.
The mixing valve allows the water heater to
operate above 140°F to protect from
condensation, while still allowing a delivery of
colder water to the system fixtures. Also
inherent in this design is the protection of
occupants from water containing bacteria
such as Legionella. Legionella can be
significantly reduced in the water storage
vessel by heating the water to a minimum of
140°F. (See Appendix A for piping details.)
WATER VELOCITY CONTROL
IMPORTANT
To ensure proper velocity through the heat
exchanger, it is necessary to regulate the
temperature rise across the heat exchanger
from inlet to outlet. (This
must be done on
initial installation and periodically rechecked).
With the correct temperature rise across the
heat exchanger (See TABLE F), you may be
assured of the proper velocity in the tubes
and long life and economical operation from
the water heater.
PUMP OPERATION
The water heater MUST be connected
with a properly sized and installed,
intermittent operating, all bronze pump
that circulates water between heater
and storage tank.
The pump is sized to heater input and
water hardness. Should water hardness
exceed 25 grains/350 TDS, consult
factory for pump sizing.
The pump chart (TABLE H) is based on the
following fittings:
6-90° elbows 2 ball valves
2 unions 1 cold water supply tee
Lochinvar
12
L o c h i n v a r
D E S I G N E R
’
S G U I D E C O P P E R
-
F I N W A T E R H E A T E R
6 1 5 - 8 8 9 - 8 9 0 0
(TABLE F) - REQUIRED TEMPERATURE RISE
MODEL NUMBER TEMPERATURE RISE °F
CW 495 15
CW 645 19
CW 745 22
CW 986 19
CW 1256 24
CW 1436 27
CW 1796 34
CW 2066 39
1.
2.