CSX Instantaneous Steam-to-Water Heater
High-Temperature Blend-down System
Designed for Buildings with Re-circulating Domestic Water Loops
High-temperature blend-down is an approach
to domestic water heating where potable water is
initially heated by a steam heat exchanger to 220ºF to
250ºF and then is blended with cold water through a
mixing valve to achieve the required outlet tempera-
ture. The approach avoids modulating steam to control
water temperature and instead relies on the modulation
of fl ows of cold and hot water.
CSX Compared to Competitive Blend-Down
Water Heaters with Building Re-Circulation
Greater Temperature Accuracy - dual control valves
CSX controls the blending of hot and cold water
through two separate fi xed-temperature mixing valves
downstream of the heat exchanger. With a building
re-circualtion loop, both valves are always blending.
Greater Safety - high-limit shutdown system
CSX is equipped with a high-temperature shutoff
device on the hot water piping. Thermostats monitor the
downstream side of both blending valves. A solenoid
valve shuts off fl ow from the heat exchanger if water
temperatures climb above either high-limit threshold.
True Clean-in-Place Capability
Unlike competitive designs that require the breaking
of piping connections or the removal of blending valves
to access the waterside of the heat exchanger, CSX
provides two readily accessible CIP threaded fi ttings.
All piping remains intack during cleaning.
Variable “Cold” Water Temperature is No Problem
The dual CSX blending valves respond seamlessly
to variable temperature and fl ow at the cold inlet port
and produce water within 5 degrees of the system’s
setpoint temperature.
Competitive designs use a blending valve that
responds to fl ow as the only variable input. Using this
type of valve requires the cold water temperature at
the valve inlet to remain constant. With a building recir-
culating loop, water at the valve’s cold inlet can range
from 40ºF to 110ºF. The valve has no internal means to
adjust to this variable and can miss the outlet tempera-
ture target by a wide margin. Without additional down-
stream blending valves, over- or under-temperature
water can enter the domestic water system.
CSX single-exchanger models range in
output from 15 to 75gpm of 140ºF water with
15 psi steam. Packaged dual-exchanger
systems are available.
Fixed-temperature valves (tamper-proof) are
available to provide 120ºF, 140ºF or 160ºF
outlet water to within ± 5 ºF. Valve failure
results in cold water fl ow.
Exchanger is passivated 316L stainless steel
with corrugated, helical tubing and a counter-
fl ow design for low fl oor space requirements.
Water is in the shell and steam in the tubes.
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