Product Overview

Instantaneous production of hot water
Caleffi 5231 series thermostatic mixing valves are designed for use on
domestic water heaters that have storage. The valve may deliver fluctuating
mixed temperatures when used on instantaneous domestic water heaters.
Radiant heating systems
Caleffi Series 5231 thermostatic mixing valves can also be used for
controlling the flow temperature in radiant heating systems, for constant and
accurate control with ease of installation.
Installation
Before installing a Caleffi 5231 series thermostatic mixing valve, the system
must be inspected to ensure that operating conditions are within the range
of the mixing valve, checking, for example, the supply temperature, supply
pressure, etc.
Systems where the Caleffi 5231 series thermostatic mixing valve will be
installed must be drained and cleaned out to remove any dirt or debris which
may have accumulated during installation. Failure to remove dirt or debris
may affect performance and the manufacturer’s product guarantee. For
heating applications demineralized water use is highly recommended as the
warranty is voided if used on water with hardness greater than 10 grains.
The installation of filters of appropriate capacity at the inlet of the water from
the supply line is always advisable.
The water must be sufficienctly treated before it enters the valve in areas
with highly agressive water. Caleffi 5231 series thermostatic mixing valves
must be installed in accordance with the diagrams in this manual, taking into
account all current applicable standards.
Caleffi 5231 series thermostatic mixing valves can be installed in any
position, either vertical or horizontal.
The following are shown on the thermostatic mixing valves body:
- Hot water inlet, color red.
- Cold water inlet, color blue.
- Mixed water outlet, marked “MIX”.
In systems with thermostatic mixing valves, check valves must be installed
to prevent undesirable fluid backflow. The 5231 is approved to ASSE 1017,
and as such does not contain integral check valves. Caleffi offers inlet port
check valve assemblies separately, for field installation only to the 5231
series valve. It is essential that access to the valve is totally unobstructed
for any maintenance which may be required to the valve or connections.
The piping from/to the valve must not be used to support the weight of the
valve itself.
Commissioning
After installation, the valve must be tested and commissioned in accordance
with the instructions given below, taking into account current applicable
standards.
1) The system must be clean and free from any dirt or debris
before commissioning the thermostatic mixing valves. Be sure water
hardness is less than 10 grains.
2) It is recommended that the temperature is set using a suitable calibrated
digital thermometer. The valve must be commissioned by measuring the
temperature of the mixed water at the outlet.
3) The maximum outlet temperature from the valve must be set taking account
of the fluctuations due to simultaneous use.
4) Adjust the temperature using the adjusting knob on the valve.
For safety reasons, it is advisable to limit the maximum mixed water
temperature to 120°F in domestic hot water systems.
Caution: In systems with thermostatic mixing
valves, check valves must be installed to prevent
undesirable fluid backflow. Separately sourced
check valve assemblies for field installation are
available for 5231 models.
Use
Caleffi 5231 series thermostatic mixing valves are designed to be installed at the
hot water heater and cannot be used for tempering water temperature at fixtures
as a point-of-use valve. They are not designed to provide scald protection or
anti-chill service and should not be used where ASSE 1070 devices are required.
For safety reasons, it is advisable to limit the maximum mixed water temperature
to 120°F for plumbing applications.
Principle of Operation
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.
Construction details
Double seat
The mixing valve has a special actuator which acts on a double
water passage seat. This produces a high flow rate with a reduced
resistance, at the same time maintaining accurate temperature control.
Anti-wear surfaces
The materials of construction in the 5231 series thermostatic mixing
valve reduces the problem of jamming caused by mineral deposits. All
the working parts, such as the PPSG40 shutter and peroxide-cured
EPDM seals, are made of a special anti-scale material, with a low
friction coefficient, providing long term high performance.
Low inertia thermostat
The temperature-sensitive element, the “motor” of the thermostatic
mixing valve, is characterized by a low heat inertia; this means that it
reacts rapidly to variations in the incoming temperature and pressure
conditions, reducing the valve response times.
Temperature setting and locking
The control knob permits temperature setting, between min. and
max., in one turn (360°). It also has a tamper-proof system to lock the
temperature at the set value.
HOT
MIXED
COLD
HOT
MIXED
COLD
without inlet check valves
with inlet check valves (field installed)