Function
The thermostatic mixer is used in solar thermal systems
producing domestic hot water. Its function is to maintain the
temperature of the mixed water supplied to the user constant at
the set value when there are variations in the supply conditions
of the incoming hot and cold water. This particular series of
mixing valves can function continuously at the high
temperatures of incoming hot water from the solar storage tank.
The valve has been specifically certified to ASSE 1017.
Product range
Series 2521 thermostatic mixing valve. Union thread NPT male
connections, sizes 1/2”, 3/4”,1”; union solder connection, size
1/2”, 3/4”, 1”.
Technical Characteristics
· Materials: - Body: Low‐lead brass
(<0.25% Lead content), chrome plated
- Shutter: PSU
- Springs: Stainless steel
- Seals: EPDM
· Setting range: 85–150°F (30–65°C)
· Accuracy: ±3°F (±2°C)
· Max working pressure (static): 200 psi (14 Bar)
· Max working pressure (dynamic): 75 psi (5 bar)
· Min working pressure (dynamic): 3 psi (0.2 bar)
· Max hot water inlet temperature: 212°F (100°C)
· Maximum inlet pressure ratio (H/C or C/H): 2:1
· Minimum temperature difference between hot water inlet and
mixed water outlet for optimum performance: 30°F (15°C)
· Min. flow rate to ensure stable temperature: 1.3 gpm (5 lpm)
· Certified to: ASSE 1017
· Lead Plumbing Law Compliance: (0.25% Max. weighted
average lead content)
· Lead Plumbing Law Certified by IAPMO R&T
Adjustable Thermostatic Mixing Valve for Solar Systems
2521 Series
28114.01
Installation, commissioning and servicing instructions
ASSE 1017
© C opyright 2010 C a l ef f i
www.caleffi.com
CALEFFI
CAUTION: If the thermostatic mixer is not installed, commissioned and
maintained properly, according to the instructions contained in this
manual, it may not operate correctly and may endanger the user.
CAUTION: Make sure that all the connecting pipework is water tight.
CAUTION: If installing in an ASSE 1017 application, check valves shall
be used.
CAUTION: When making the water connections, make sure that the mixer
connecting pipework is not mechanically over-stressed. Over time this
could cause breakages, with consequent water losses which, in turn,
could cause harm to property and/or people.
CAUTION: Water temperatures higher than 100°F can be dangerous.
During the installation, commissioning and maintenance of the
thermostatic mixer, take the necessary precautions to ensure that such
temperatures do not endanger people.
CAUTION: In the case of highly aggressive water, arrangements must be
made to treat the water before it enters the thermostatic mixer, in
accordance with current legislation. Otherwise the mixer may be damaged
and will not operate correctly.
Leave this manual for the user.
SAFETY INSTRUCTION
This safety alert symbol will be used in this manual to draw attention to safety related
instructions. When used, the safety alert symbol means ATTENTION! BECOME ALERT!
YOUR SAFETY IS INVOLVED! FAILURE TO FOLLOW THESE INSTRUCTIONS MAY
RESULT IN A SAFETY HAZARD.
CAUTION: All work must be performed by qualified personnel trained in the
proper application, installation, and maintenance of systems in accordance
with all applicable codes and ordinances.
Operating Principle
The controlling element of the solar thermostatic
mixing valve is a temperature sensor that is fully
immersed in the mixed water outlet passage. As
it expands or contracts, the sensor continuously
establishes the correct proportion of hot and
cold water entering the valve. The flow is
regulated by a piston sliding in a cylinder
between the hot and
cold water passages.
Even when there are
pressure drops due to
the drawing off of hot or
cold water for other uses
or variations in the
incoming temperature,
the mixer automatically
regulates the water flow
to obtain the required
temperature.
Flow curves
Kv = 2.6
10
0.01
0
.
1
0
.
02
0
.
03
2
5
0.05
1
0.2
0
.
3
0.
5
20
50
∆p (psi)
G (l/min) (
gpm
)
10
2
3
5
2
0
0
.
01
0
.
1
0
.
02
0
.
03
0.05
1
0
.
2
0
.
3
0.
5
(psi) (bar)
10
2
3
5
2
0
1
0.5
10
2
5
2
0
0.001
0
.
01
0
.
002
0
.
003
0.005
0.1
0
.
02
0
.
03
0
.
05
1
.
0
0
.2
0.3
0
.
5
Cv = 3.0
4
0
.04
0.4
0
.04
0.4
4
0.0
04
0.0
4
0
.4
COLD
HOT
MIX
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