Danfoss for MR2A Mixing Shunt Installation guide

Danfoss
Brand
Danfoss
Model
for MR2A Mixing Shunt
Type
Installation guide

Danfoss for MR2A Mixing Shunt

The MR2A mixing shunt allows you to connect up to two underfloor heating circuits. It features an adjustable mixing valve for precise temperature control, an adjustable bypass for the radiator or boiler circuit, and an integrated ball valve for easy isolation. Other features include:

  • Electric actuator compatible with room thermostats for temperature-controlled operation.
  • Shaftless spherical circulation pump for efficient and quiet operation.
  • Built-in protection against excessive temperatures.
  • Easy installation with wall mounting bracket and horizontal pump orientation.

Danfoss for MR2A Mixing Shunt

The MR2A mixing shunt allows you to connect up to two underfloor heating circuits. It features an adjustable mixing valve for precise temperature control, an adjustable bypass for the radiator or boiler circuit, and an integrated ball valve for easy isolation. Other features include:

  • Electric actuator compatible with room thermostats for temperature-controlled operation.
  • Shaftless spherical circulation pump for efficient and quiet operation.
  • Built-in protection against excessive temperatures.
  • Easy installation with wall mounting bracket and horizontal pump orientation.
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The MR 2 A mixing shunt is designed to supply
floor heating areas up to approx. 30 m
2
(from pipe
16 x 2 mm onwards) in one- or two-pipe-systems.
The connection of up to 2 floor heating circuits is
possible.
MR 2 A is a mixing set for room temperature
guided control, made of thermoelectric actuator
for the connection of a room thermostat.
The MR 2 A is provided with a temperature pro-
tection system that restricts the supply tempera-
ture in the floor heating circuit to max. 55° C.
Application and design
Max. system pressure 1 Mpa (10 bar)
Max. system temperature 110° C (boiler circuit), 55° C (floor heating)
Max. differential pressure 100 kPa (1 bar) in the radiator-/boiler circuit
Electrical connection 1 x 230 V / 50 Hz
Power consumption 25 Watt (circulating pump)
Instruction
Installation and operation manual
for mixing shunt MR 2 A
Danfoss HES VI.SP.O1.02 © Danfoss 11/2008 1
Technical data
1. Electric actuator for the
connection of a room
thermostat
2. Shaftless spherical circulation
pump
3. Venting device
4. Supply radiator-/boiler circuit
5. Return radiator-/boiler circuit
6. Supply floor heating circuit
7. Return floor heating circuit
8. Adjustable mixing valve
9. Adjustable bypass for the
radiator-/boiler circuit
10. On-/off-switch
11. Integrated ball valve
Mounting
• MR2Awillbeconnecteddirectlytotheexisting
radiator-/boiler circuit.
• WhentwocircuitsareconnectedtotheMR2A,
the shortest circuit must be balanced by using
an adjustable return screw connection.
• TheMR2Ahastobemountedinahorizontal
position. Left or right connection to the radiator-
/boiler circuit is possible.
• TheMR2Ahastobeinstalledonahigherlevel
than the floor heating installation.
• Ensurethatthepre-pressuretotheMR2Afrom
the radiator-/vessel circuit is minimum 10 kPa.
• BeforerunningtheMR2Apleasecheck,that
the floor heating system is filled, completely
vented, and proved against leakage.
Note!
Please ensure that the mixing unit UFH system
is primed independently. It must not be primed
from the primary system (feed from the boiler).
• Sincethecirculationpumpmightcreateunder
certain circumstances some flow noise, the
mini shunt should be placed away from noise
sensitive areas (i.e. sleeping rooms).
• Thewatertemperatureinthesupplyradiator-/
boiler circuit should be at least 10 K higher than
in the floor heating supply.
• Themaximumlengthofeachpipemustnot
be longer than 100 m for floor heating design
with a ∆T of 10 K when using pipes 12 mm i.d.
(i.e. pipe 16x2). Smaller diameter pipe results in
a shorter pipe length.
• Wiringoftheelectricalactuatorandtheroom
thermostat only by a qualified electrician.
Instruction Installation and operation manual for mixing set MR 2 A
It is mandatory to flush the floor heating loops
before putting the system in operation, because
otherwise malfunction or damage to the pump
may result.
Danfoss recommends using two fill valves on the
primary side of the mini shunt as shown in picture 2.
Alternatively, the system can be filled using fill
valves installed elsewhere in the system. In any
case, it is necessary to positively flush the system
since otherwise the air in the system will not be
purged completely.
Filling the system via the integrated manual air
vent (see picture 7) is not possible!
Please observe the position of the ball valve in the
bypass. If this is in the vertical position, the floor
heating loops are hydraulically uncoupled from
the boiler loop. This position is ideal for normal
operation (see picture 1) since the pump in the
heating loop does not influence the floor heating
loop. With the valve in this position, however, the
floor heating system cannot be filled from the
primary side.
To fill the floor heating loops from the heating loop
side, this ball valve must be closed (horizontal),
see pictures 2 to 6.
After filling, the valve must be opened again
(vertical position). Please observe that when
filling from the primary side radiator valves
on that side should be closed in order to have
maximum pump pressure available for purging
the floor heating loops.
2 VI.SP.O1.02 © Danfoss 11/2008 Danfoss HES
Hydraulic connection
of two-pipe systems
Bypass valve closed (Allen key 2.5 mm)
Filling of the system
Picture 1.
Normal operation. Ball
valve position open
(vertical).
!!!
Instruction Installation and operation manual for mixing set MR 2 A
Danfoss HES VI.SP.O1.02 © Danfoss 11/2008 3
Picture 2.
Recommended filling of
the system. Two fill valves
on the primary side of the
mini shunt allow for an easy
filling and purging of air in
the floor heating loops. The
ball valve position must be
closed (horizontal).
!!!
Picture 3.
Good filling option. Two
existing fill valves on the
primary side allow for good
filling and air purging. The
ball valve position must be
closed (horizontal).
!!!
Picture 4.
Possible filling option, albeit
a little complicated. One fill
valve on the primary flow
side allows for filling and
air purging. The integrated
ball valve must be closed
(horizontal). Caution: The
floor heating return at the
mini shunt must be closed
during the fill operation.
Filling a wall heating loop is
impossible in this way.
!!!
Instruction Installation and operation manual for mixing set MR 2 A
4 VI.SP.O1.02 © Danfoss 11/2008 Danfoss HES
Picture 5.
Possible filling option, albeit
a little complicated. One fill
valve on the primary return
side allows for filling and
air purging. The integrated
ball valve must be closed
(horizontal).
Caution: The floor heating
flow at the mini shunt must
be closed during the fill
operation. Filling a wall
heating loop is impossible
in this way.
!!!
Picture 6.
The direction of flow shown
is only possible if there is no
check valve installed at the
primary heating circuit. If a
check valve is present, filling
in accordance with picture 3
is recommended.
!!!
Picture 7.
Filling the system in this
way is impossible since
no forced flushing can be
assured.
Instruction Installation and operation manual for mixing set MR 2 A
Danfoss HES VI.SP.O1.02 © Danfoss 11/2008 5
1. Remove protection cap / or thermostatic head
/ or electric actuator from the MR 2 A (see page 8,
picture 1).
2. Increase the supply temperature from the
radiator-/boiler circuit to the designed value
(normally 55-60°C).
3. To perform the adjustment check, the room
temperature has to be at least 20°C. If it is not,
the system has to be run until the temperature
increases.
Starting of operation
without given values
4. Check the floor heating supply temperature. It
should be about 35-40°C. If it is too high, the
flow from the primary supply has to be adjusted
(reduced), see page 3 picture 3.
The MR 2 A will be delivered from factory with
fully opened mixing valve. We recommend an
adjustment in small steps (1/2 turn). After each
adjustment the floor heating supply temperature
should be checked after an appropriate waiting
period.
E.g. Given values:
Heat requirement of
underfloor heating system 2000 Watt
Supply temperature of
radiator-/boiler system 70 °C
Return temperature of
underfloor heating system 40 °C
Difference pressure of the
radiator-/boiler circuit 10 kPa
Specific heat capacity of water 1.163
W
/
(Kg x K)
Starting of operation
with given values
(pre-setting)
Wanted values:
Flow from the radiator-/boiler circuit :
m = Q/(c x ∆T) = 2000 W / (1.163
W
/
(kg x K)
x 30 K) =
58 l/h
Pre-setting:
If the difference pressure from the radiator-/boiler
circuit at the inlet and outlet of the MR 2 A is 10
kPa and the flow requirement of the MR 2 A is
about 60 l, the mixing valve presetting has been
opened by 1.6 turns.
Instruction Installation and operation manual for mixing set MR 2 A
6 VI.SP.O1.02 © Danfoss 11/2008 Danfoss HES
1.
Remove protection cap
/ actuator
2.
Remove valve insert
3.
Use enclosed tool to
adjust the pre-setting of
the mixing valve
4.
Screw valve insert in
again
Replacing the
valve insert
Assembling of
wall bracket
The MR 2 A can be mounted to the wall bracket
with radiator-/boiler connections to the left of to
the right side. The screws for the mounting of the
MR 2 A to the wall bracket are enclosed.
Installation of the MR 2 A only with horizontal
pump. Mixing valve and venting device have to
show upwards.
For a silencing of the sound the enclosed rubber bumpers have to be used between mounting bracket
and wall, or - if mounted in a cabinet - between mounting bracket and fixation rails.
Instruction Installation and operation manual for mixing set MR 2 A
Danfoss HES VI.SP.O1.02 © Danfoss 11/2008 7
Pump operation
Pump curve
Continous operating
of pump
230 V~
L
N
RET 230P
Electronic
NO
NC
N L 1 2 3
Pump also switched off
by room thermostat
230 V~
L
N
RET 230P
Electronic
NO
NC
N L 1 2 3
230 V~
L
N
Thermal
electrical
actuator
(230 V, NC)
Pump
brown
blue
brown
blue
yellow/green
Pump
brown
blue
brown
blue
yellow/green
Output:
1 = ON
2 = OFF
3 = COM
Link terminals L
and COM/3 for
230V output
Output:
1 = ON
2 = OFF
3 = COM
Link terminals L
and COM/3 for
230V output
Thermal
electrical
actuator
(230 V, NC)
Instruction Installation and operation manual for mixing set MR 2 A
8 VI.SP.O1.02 © Danfoss 11/2008 Danfoss HES
Dimensions
Dimensions, cabinets
Width Height Depth
Surface mounted 415 mm 310 mm 115 mm
Flush mounted 400 mm 330 mm 110 - 150 mm
  • Page 1 1
  • Page 2 2
  • Page 3 3
  • Page 4 4
  • Page 5 5
  • Page 6 6
  • Page 7 7
  • Page 8 8

Danfoss for MR2A Mixing Shunt Installation guide

Danfoss
Brand
Danfoss
Model
for MR2A Mixing Shunt
Type
Installation guide

Danfoss for MR2A Mixing Shunt

The MR2A mixing shunt allows you to connect up to two underfloor heating circuits. It features an adjustable mixing valve for precise temperature control, an adjustable bypass for the radiator or boiler circuit, and an integrated ball valve for easy isolation. Other features include:

  • Electric actuator compatible with room thermostats for temperature-controlled operation.
  • Shaftless spherical circulation pump for efficient and quiet operation.
  • Built-in protection against excessive temperatures.
  • Easy installation with wall mounting bracket and horizontal pump orientation.
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