Install Instructions

Operating principle
A thermostatic mixing valve mixes hot and cold water in such a way as to maintain a constant set
temperature of the mixed water at the outlet.
A thermostatic element is fully immersed into the mixed water. It then contracts or expands causing
movement of the piston, closing either the hot or cold inlets, regulating the flow rates entering the
valve. If there are variations of temperature or pressure at the inlets, the internal element automatically
reacts attempting to restore the original temperature setting.
The Caleffi 5231 series mixing valves require a minimum temperature differential from hot inlet
to mixed water outlet of 20°F (11°C) to ensure the correct operation, and maximum pressure
difference between the hot and cold inlet parts no greater than 2:1 ratio. Softened water use is highly
recommended as the warranty is voided if used on water with hardness greater than 10 grains.
Control
The Caleffi 5231 series
mixing valves require a
minimum temperature
differential from hot inlet to
mixed water outlet of 20°F
(11°C) to ensure the correct
operation, and maximum
pressure difference
between the hot and cold
inlet parts no greater than
2:1 ratio. Softened water
use is highly recommended
as the warranty is voided
if used on water with
hardness greater than 10
grains.
Check valves field installed only: code NA10366 for 1” & 1¼”
sizes; code NA10367 for 1½” & 2” sizes.
4
HOT
MIXED
COLD
HOT
MIXED
COLD
without inlet check valves
with inlet check valves (field installed)