CALEFFI 2521 Series User guide

Function
The thermostatic mixer is used in solar thermal systems
producing domestic hot water. Its unction is to maintain the
temperature o the mixed water supplied to the user constant at
the set value when there are variations in the supply conditions
o the incoming hot and cold water. This particular series o
mixing valves can unction continuously at the high
temperatures o incoming hot water rom the solar storage tank.
The valve has been speci ically certi ied 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 di erence between hot water inlet and
mixed water outlet or optimum per ormance: 30°F (15°C)
· Min. low rate to ensure stable temperature: 1.3 gpm (5 lpm)
· Certi ied to: ASSE 1017
· Lead Plumbing Law Compliance: (0.25% Max. weighted
average lead content)
· Lead Plumbing Law Certi ied by IAPMO R&T
Adjustable Thermostatic Mixing Valve for Solar Systems
2521 Series
28114.01
Installation, commissioning and servicing instructions
ASSE 1017
© Copyright 2010 Caleffi
www.caleffi.com
CALEFFI

CAUTION: I 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: I 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 o the
thermostatic mixer, take the necessary precautions to ensure that such
temperatures do not endanger people.
CAUTION: In the case o highly aggressive water, arrangements must be
made to treat the water be ore 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 sa ety alert symbol will be used in this manual to draw attention to sa ety related
instructions. When used, the sa ety alert symbol means ATTENTION! BECOME ALERT!
YOUR SAFETY IS INVOLVED! FAILURE TO FOLLO THESE INSTRUCTIONS MAY
RESULT IN A SAFETY HAZARD.
CAUTION: All work must be per ormed by quali ied personnel trained in the
proper application, installation, and maintenance o systems in accordance
with all applicable codes and ordinances.

O erating Princi le
The controlling element o the solar thermostatic
mixing valve is a temperature sensor that is ully
immersed in the mixed water outlet passage. As
it expands or contracts, the sensor continuously
establishes the correct proportion o hot and
cold water entering the valve. The low 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 o o hot or
cold water or other uses
or variations in the
incoming temperature,
the mixer automatically
regulates the water low
to obtain the required
temperature.
Flow curves
Kv = 2.6
10
0 . 01
0
. 1
0
. 02
0
. 03
2 5
0 .0 5
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 .0 5
1
0
. 2
0
. 3
0. 5
(psi) (bar)
10
2
3
5
2 0
1 0.5 10 2 5 20
0 . 001
0
. 01
0
. 002
0
. 003
0 . 0 0 5
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

16
14
13
12
11
9
10
8
4
6
7
5
2
3
15
15
16
MIX
COLD HOT
17
1
Ex loded diagram
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Reg lating knob
Head fixing screw
Reg lating spindle
“O” Ring seal
Upper sh tter seat
Thermostatic element
Inner sh tter
“O” Ring
O ter sh tter
“O” Ring
“O” Ring
Spring cover
Spring
Valve body
Union n t
Gasket
Tail piece body

Installation
Be ore installing a Cale i 2521 series mixing valve, the system
must be inspected to ensure that its operating conditions are
within the range o the mixer, checking, or example, the supply
temperature, supply pressure, etc.
Systems where the Cale i 2521 series mixing valve is to be
itted 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 a ect per ormance
and the manu acturer's product guarantee.
The installation o ilters o appropriate capacity at the inlet
o the water rom main supply is always advisable.
In areas which are subject to highly aggressive water,
arrangements must be made to treat the water be ore it
enters the valve.
Cale i 2521 series mixing valve must be installed in accordance
with the diagrams in this manual, taking into account all current
applicable standards.
Cale i 2521 series mixing valve can be installed in any position,
either vertical or horizontal.
The ollowing are shown on the valve body:
- Hot water inlet, color red and marked “HOT”.
- Cold water inlet, color blue and marked “COLD”.
- Mixed water outlet, marked “MIX”.
It is essential that access to the valve is totally unobstructed or
any maintenance which may be required to the valve or
connections. The pipework rom/to the valve must not be used to
support the weight o the valve itsel .
Use
Thermostatic mixing valves are typically installed at the
outlet o hot water storage tanks in solar systems to ensure
constant temperature o the mixed water supplied to the end user.
Because o their low characteristics, the valves can be installed
to control the temperature or both single point o use and or point
o distribution. In order to guarantee the delivery o mixed water at
the set temperature, the 2521 series thermostatic mixing valves
must have a minimum low rate o 1.3 gpm.

Application Diagrams
COLD/BLUEHOT/RED
MIX
Key to symbols
Safety relief valve
Isolation and check valve
Isolation valve
Expansion vessel
Filter
HOT
COLD
MIX
MIN M A X 7 1 2
HOT
COLD
CALEFFI
MIN
M
A
X
7
1
2
T
Normally closed
valve
T

Commissioning
A ter installation, the valve must be tested and commissioned in
accordance with the instructions given below, taking into account
current applicable standards.
1) Ensure that the system is clean and ree rom any dirt or debris
be ore commissioning the thermostatic mixer.
2) It is recommended that the temperature is set using a suitable
calibrated digital thermometer. The valve must be
commissioned by measuring the temperature o the mixed
water emerging at the point o use.
3) The maximum outlet temperature rom the valve must be set
taking account o the luctuations due to simultaneous use.
It is essential or these conditions to be stabilised be ore
commissioning.
4) Adjust the temperature using the adjusting knob on the valve.
For sa ety reasons, it is advisable to limit the maximum mixed
water temperature to 120°F in domestic hot water systems.
Setting the tem erature
The temperature is set to the required value by means o the
adjusting knob with the graduated scale on the top o the valve.
Preset locking
Position the handle to the number required. Unscrew the head
screw, pull o the handle and reposition it so that the handle its
into the internal slot o the knob. Tighten the head screw.
Maintenance
In service tests should be carried out regularly to monitor the
mixer per ormance, as deterioration o per ormance could
indicate that the valve and/or the system require maintenance. I ,
during these tests, the temperature o the mixed water has
changed signi icantly in comparison with the previous test, the
details given in the installation and commissioning sections
should be checked and maintenance carried out.
The ollowing aspects should be checked regularly to ensure that
the optimum per ormance levels o the valve are maintained.
Every 12 months at least, or more o ten i necessary.
1) Check and clean the system ilters.
2) Veri y that any check valves positioned upstream o the Cale i
valve are operating correctly, without problems caused by
impurities.
3) The Cale i valve should not be dismantled. Limescale can be
removed rom internal components by immersion in a suitable
de-scaling luid.
4) When the components which can be maintained have been
checked, commissioning should be carried out again.
Min 1 2 3 4 5 6 7 Max
81 90 100 111 120 127 136 145 152
Pos.
27 32 38 44 49 53 58 63 67
M
I
N
M
A
X
7
1
2
3

Troubleshooting
Under normal operating conditions the Cale i 2521 series mixing valve will provide a very
high level o per ormance. However, in some circumstances, where our maintenance plan is
not ollowed, the ollowing problems may arise.
Sym tom
Fluctuating mixed water
temperature
Erratic low o water rom
the valve
No low o water rom the
valve
Cause
a) Erratic supply temperatures
at the inlets o the valve.
b) Starvation o the water
supplies at the inlets
o the valve.
c) Incorrect commissioning
o the valve.
a) Insu icient water supplies.
b) Fluctuations in supply
pressures/temperatures.
c) Adverse e ect created
by other draw o points
on the system.
a) In-line ilters blocked.
b) Insu icient supply pressures.
c) Debris obstructing valve
operation.
Corrective action
·Restore inlet conditions
within the limits o the
valve.
·Stabilize inlet supply
conditions.
·Clean ilters.
·Restore inlet supplies.
·Clean debris or scale
rom valve.
Caleffi North America, Inc.
3883 est Milwaukee Road
Milwaukee, I 53208
T: 414.238.2360 F: 414.238.2366
CALEFFI
Safety
The thermostatic mixer must be installed by a licensed plumber in accordance
with national regulations and/or relevant local requirements.
I 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.
Make sure that all the connecting pipework is water tight.
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.
Water temperatures higher than 100°F can cause serious burns.
During the installation, commissioning and maintenance o the thermostatic mixer, take the
necessary precautions to ensure that such temperatures do not endanger people.
In the case o highly aggressive water, arrangements must be made to treat the water be ore
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.