PAW FriwaMidi DN 20 User manual

PAW GmbH & Co.KG
Böcklerstr. 11, 31789 Hameln - Germany
Phone: [phone], Fax: [phone]
E-mail: [email protected], Web: www.paw.eu
2020/06 99640x5xx-mub-en – V01 1
Installation and Operation Instructions
Domestic hot water modules
FriwaMidi – DN 20
FriwaMaxi – DN 25

1General Information
2 99640x5xx-mub-en – V01 2020/06
Item no. 99640x5xx-mub-en - Version V01 - Issued 2020/06
Translation of the original instructions
We reserve the right to make technical changes without notice!
Printed in Germany – Copyright by PAW GmbH & Co. KG
PAW GmbH & Co.KG
Böcklerstraße 11
31789 Hameln
Germany

1General Information
2020/06 99640x5xx-mub-en – V01 3
Contents
1General Information.........................................................................................................4
1.1 Scope of these instructions ..........................................................................................4
1.2 About this product ........................................................................................................5
1.3 Designated use ............................................................................................................5
2Safety instructions ...........................................................................................................6
3Product description..........................................................................................................8
4Dimensioning and planning..............................................................................................9
4.1 Dimensioning of the tank............................................................................................10
4.2 Water quality requirements.........................................................................................11
5Circulation mode ...........................................................................................................13
6Mounting and installation [specialist] ..............................................................................14
7Commissioning [specialist].............................................................................................17
7.1 Filling the primary circuit.............................................................................................18
7.2 Commissioning of the controller ................................................................................. 19
7.3 Maximum withdrawal flow rate ...................................................................................21
7.4 Adjustment of the temperature ................................................................................... 23
8Maintenance .................................................................................................................25
9Disposal........................................................................................................................26
10 Spare parts [specialist] ..................................................................................................27
10.1 Spare parts control and insulation
FriwaMidi without circulation (6405510 + 6405530) / with circulation (6405515 + 6405535).. 27
10.2 Spare parts hydraulics
FriwaMidi without circulation (6405510 + 6405530) / with circulation (6405515 + 6405535).. 28
10.3 Spare parts control and insulation
FriwaMaxi without circulation (6406510 + 6406530) / with circulation (6406515 + 6406535). 29
10.4 Spare parts hydraulics
FriwaMaxi without circulation (6406510 + 6406530) / with circulation (6406515 + 6406535) 30
11 Technical data...............................................................................................................33
11.1 Pressure drop characteristics FriwaMidi..................................................................... 34
11.2 Pressure drop characteristics FriwaMaxi.................................................................... 34
12 Commissioning report....................................................................................................35

1General Information
4 99640x5xx-mub-en – V01 2020/06
1General Information
1.1 Scope of these instructions
These instructions describe the installation, commissioning, function and operation of the
domestic hot water modules FriwaMidi and FriwaMaxi. The chapters called [specialist] are
intended for specialists only.
For other components of the system, such as tanks, controllers or pumps, please observe the
instructions of the corresponding manufacturer.
Station
Item
number
Controller
FC3.10
Pump,
primary
Circulation
Heat
exchanger
FriwaMidi
6405510
Grundfos
UPM2 25-75 / Copper
solder,
40 plates
FriwaMidi with
circulation
6405515
Grundfos
UPM2 25-75
Grundfos
UPM2 15-75 CIL
FriwaMidi
6405530
Grundfos
UPM2 25-75
/
Coated,
40 plates
FriwaMidi with
circulation
6405535
Grundfos
UPM2 25-75
Grundfos
UPM2 15-75 CIL
Station
Item
number
Controller
FC4.13
Pump,
primary
Circulation
Heat
exchanger
FriwaMaxi
6406510
Grundfos
UPML 25-105 / Copper
solder,
60 plates
FriwaMaxi with
circulation
6406515
Grundfos
UPML 25-105
Grundfos
UPM2 15-75 CIL
FriwaMaxi
6406530
Grundfos
UPML 25-105 /
Coated,
60 plates
FriwaMaxi with
circulation
6406535
Grundfos
UPML 25-105
Grundfos
UPM2 15-75 CIL
Carefully read these instructions before installation and commissioning. Save
these instructions in the vicinity of the installation for future reference.

1General Information
2020/06 99640x5xx-mub-en – V01 5
CE Declaration of Conformity
The domestic hot water module complies with the relevant directives and is therefore labelled
with the CE mark. The Declaration of Conformity is available upon request, please contact the
manufacturer.
1.2 About this product
The FriwaMidi and FriwaMaxi are domestic hot water modules which heat potable water
operating on the principle of a flow-type water heater.
The domestic hot water module is a premounted group of fittings checked for tightness and
used to transfer the heat between the buffer tank and the domestic hot water circuit. It contains
a preset controller and important fittings for the operation of the system:
•Ball valves in the primary circuit
•Piston valves in the secondary circuit
•Pressure relief valve in the secondary circuit
•Premounted controller
•Temperature sensor at the cold water inlet
•Temperature sensors at the heating flow
•Temperature sensor at the domestic hot water outlet
•Flow meter at the domestic hot water outlet
•Fill and drain valve to drain the heat exchanger
•Vent plug to vent the heat exchanger
1.3 Designated use
The domestic hot water module must only be mounted in heating installations between the
buffer tank and the domestic hot water circuit. Due to its design, the station must be mounted
and operated in a vertical position! The technical limit values specified in these instructions must
be observed.
Only use PAW accessories with the domestic hot water module.
Using the station contrary to its designated use will invalidate all liability claims.
Do not put the module into operation in case of any visible damage.

2Safety instructions
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2Safety instructions
The installation and commissioning as well as the connection of electrical components require
technical knowledge commensurate with a recognised vocational qualification as a fitter for
plumbing, heating and air conditioning technology, or a profession requiring a comparable level
of knowledge [specialist].
The following must be observed during installation and commissioning:
•Relevant local and national regulations
•Accident prevention regulations of the professional association
•Instructions and safety instructions mentioned in these instructions
WARNING
Danger of scalding due to hot water!
Undesirable circulation of water in the primary circuit can cause the exit of water
of up to 90 °C at the withdrawal point.
External pumps must not be installed between the domestic hot water
module and the buffer tank.
The domestic hot water module must not be connected to a distribution
manifold of a heating circuit.
CAUTION
Risk of burns!
The valves, fittings and the pump may heat up to more than 95 °C during
operation.
The insulating shell must remain closed during operation.

2Safety instructions
2020/06 99640x5xx-mub-en – V01 7
ATTENTION
Material damage due to mineral oils!
Mineral oil products cause permanent damage in the material, resulting in its sealing
characteristics getting lost. We cannot be held liable for damage caused by seals damaged in
this way, and nor will we give warranty replacement for such parts.
It is imperative to prevent the EPDM sealing elements from making contact with
substances containing mineral oils.
Use a silicone- or polyalkylene-based lubricant free of mineral oil such as Unisilikon
L250L and Syntheso Glep 1 from Klüber or a silicone spray.
ATTENTION
Malfunction!
The domestic hot water module must be integrated in the potential equalisation of the
electric installation. If this is not guaranteed by the pipe system, establish a potential
equalisation connection to the main potential connection according to regulations.

3Product description
8 99640x5xx-mub-en – V01 2020/06
3Product description
Example: FriwaMaxi with circulation
Connections
1 Primary side: return to the buffer tank
2 Secondary side:
hot water circulation, return
3 Secondary side: cold water inlet
4 Secondary side: hot water outlet
5 Primary side: flow from the buffer tank
Equipment
A Ball valve with check valve
B Primary pump
C Non-return valve with drain valve
D Circulation pump
E Piston valve with drain valve
F Piston valve with drain valve
G Piston valve with drain valve and
temperature sensor
H Fill and drain valve and temperature
sensor
I Flow meter FlowSonic
J Plate heat exchanger
K Circulation line
L Vent valve (primary circuit)
M Temperature sensor and pressure relief
valve 10 bars, suitable for DHW
Only for the protection of the station.
Does not replace the pressure relief valve
that has to be mounted on site!
N Ball valve with check valve

4Dimensioning and planning
2020/06 99640x5xx-mub-en – V01 9
4Dimensioning and planning
The FriwaMidi and FriwaMaxi can only work flawlessly if the installation meets certain
requirements. Please take some time to plan the assembly.
WARNING
Danger of scalding due to hot water!
Undesirable circulation of water in the primary circuit can cause the exit of water
of up to 90 °C at the withdrawal point.
External pumps must not be installed between the domestic hot water
module and the buffer tank.
The domestic hot water module must not be connected to a distribution
manifold of a heating circuit.
Mounting example
FriwaMidi with optional circulation set (item no. 640412) and with optional return distribution
(FriwaMidi: item no. 640423, FriwaMaxi: item no. 640424)
Safety group
according to DIN
1988

4Dimensioning and planning
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4.1 Dimensioning of the tank
The following table helps you to calculate the approximately required volume of the buffer tank.
Temperature in
the buffer tank
Domestic hot water
temperature set at the
controller
Required tank volume
per litre of hot water
50 °C 45 °C 1.3 litres
60 °C
45 °C 0.8 litres
50 °C 1.0 litre
55 °C 1.4 litres
70 °C
45 °C 0.7 litres
50 °C 0.8 litres
55 °C 0.9 litre
80 °C
45 °C 0.5 litres
50 °C 0.6 litres
55 °C 0.7 litres
Calculation example for the dimensioning of the buffer tank:
Temperature of the buffer tank: 60 °C
Required withdrawal flow rate at the tap: 20 l/min
Domestic hot water temperature set at the controller: 45 °C
How large must the tank be to allow for a continuous withdrawal during 20 minutes without
post-heating?
20 l/min x 20 min = 400 l
400 l x 0.8 = 320 l
The heated part of the buffer tank must have a volume of 320 litres.

4Dimensioning and planning
2020/06 99640x5xx-mub-en – V01 11
4.2 Water quality requirements
The domestic hot water modules constructively decrease the precipitation of chalk in the heat
exchanger.
For installations with an elevated total hardness of the potable water and/or high
temperatures, a water treatment is recommended.
The choice of the heat e
xchanger depends on the requirements of the installation location.
Depending on the chemical composition of the water at the installation site, the adequacy of
the plate heat exchanger has to be checked.
Please observe the following table:
Influence of the water quality on the corrosion resistance for domestic hot water applications
Water content
Concentration
(mg/l or ppm)
Time limits
Heat exchanger
with copper
solder
Coated heat
exchanger
Alkalinity (HCO3-) < 70 within
of
24 hours
0 +
70-300 + +
> 300 0/+ +
Sulphate (SO42-) < 70 no limit + +
70-300 0/- +
> 300 - +
HCO3- / SO42- > 1.0 no limit + +
< 1.0 0/- +
Electrical
conductivity
< 10 μS/cm no limit 0 +
10-500 μS/cm + +
> 500 μS/cm 0 +
pH value < 6.0 within
of
24 hours
0 +
6.0-7.5 0 +
7.5-9.0 + +
9.0-10 0 0
> 10.0 0 -

4Dimensioning and planning
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Ammonium (NH4+) < 2 within
of
24 hours
+ +
2-20 0 +
> 20 - -
Chloride (Cl-) < 100 no limit + +
100-200 + +
200-300 + +
> 300 0/+ 0
Free chlorine (Cl2) < 1 within
of
5 hours
+ +
1-5 0 0
> 5 0/- 0
Hydrogen sulphide
(H2S)
< 0.05 no limit + +
> 0.05 0/- 0
Free (aggressive)
carbon dioxide
(CO2)
< 5 no limit + +
5-20 0 +
> 20 - +
Total hardness
(°dH)
4.0-8.5 no limit + +
Nitrate (NO3-) < 100 no limit + +
> 100 0 +
Iron (Fe) < 0.2 no limit + +
> 0.2 0 +
Aluminium (Al) < 0.2 no limit + +
> 0.2 0 +
Manganese (Mn) < 0.1 no limit + +
> 0.1 0 +
+ Good durability under normal conditions
0 Corrosion may occur, especially if further factors are evaluated with 0
- Use is not recommended

5Circulation mode
2020/06 99640x5xx-mub-en – V01 13
5Circulation mode
The domestic hot water modules FriwaMidi and FriwaMaxi are optionally equipped with a
circulation pump.
The FriwaMidi and FriwaMaxi without circulation can be subsequently equipped with a
circulation set (item no. 640412).
For the operation of the circulation pump, three possible operation modes are stored in the
controller (see controller instructions, chapter
Circulation ).
•
Pulse-controlled operation
(depending on the demand / requirements):
The short actuation of a hot water tap (tap pulse: below 5 sec.) starts the circulation
pump. The circulation pump will then run for several minutes (adjustable).
•
Time-dependent operation:
The operation of the circulation pump can be set on a week clock within a freely
selectable period of time. In this operation mode, the circulation is activated at the
beginning of the period of time chosen. The circulation will stop after the end of the
chosen period of time.
•
Temperature-dependent operation:
In this operation mode, the circulation is only activated if the adjustable minimum
temperature at the circulation temperature sensor is not reached during the chosen
period of operation. The circulation stops after the required temperature has been
reached.
The operating modes can be combined with each other as wished, f. ex. the time- and the
temperature-dependent operating modes. The circulation is only activated if the temperature at
the circulation temperature sensor falls below the required value and if the time window is
active.
Outside the time slot, the circulation pump can be activated by a tap pulse if the pulse-controlled
operation mode is additionally activated.
ATTENTION
Damage to property!
When the domestic hot water module is delivered, the circulation is not activated (see
controller instructions, chapter
Circulation ). Once the circulation line mounted, it is mandatory
to select and preset the operation mode. The revolution speed of the circulation pump must
be defined by the PWM signal (factory setting: 100 %).

6Mounting and installation [specialist]
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6Mounting and installation [specialist]
The domestic hot water modules FriwaMidi and FriwaMaxi must only be connected to the
storage tank by separate connections for the flow and return. External pumps must not be
installed between the domestic hot water module and the buffer tank.
The circulation of water causes considerable temperature fluctuations.
The domestic hot water connection must be carried out in accordance with the relevant norms
(for example DIN 1988)!
ATTENTION
Damage to property!
The pressure relief valve integrated in the station does not replace the safety groups of the
potable water connection as per DIN 1988.
The pressure relief valve only protects the module from overpressures in case of servicing.
ATTENTION
Damage to property!
If there are water supplies that may cause pressure surges
(for example flush valves, washing machines or dishwashers)
connected to the same mains as the domestic hot water
module, we recommend the installation of water hammer
arresters close to the place where these pressure surges may
be caused.
Water hammer arresters
DHW
module
Fittings
Drain valve
Pressure relief valve
Return valve (non-return valve)
Possibly pressure reducing valve
Test valve
Shut-off valve
Hot water
Cold
water
Mech.
filter

6Mounting and installation [specialist]
2020/06 99640x5xx-mub-en – V01 15
WARNING
Risk to life and limb due to electric shock!
Prior to commencing electrical work on the controller, pull the mains
plug!
Only after completing all installation work, plug the mains plug of the
controller into a socket. This avoids an unintentional start of the motors.
ATTENTION
Damage to property!
The installation site must be dry, stable, frost-proof and protected against ultraviolet radiation
in order to prevent material damage of the installation.
1. Determine the mounting location of the domestic
hot water module near the buffer tank.
The pipes in the heating circuit must not exceed a
length of 4 m (for DN 32).
2. A drilling template can be used in order to facilitate
the installation. You will find the drilling template on
the station.
3. Copy the measures for the mounting holes to the
wall.
4. Drill the holes and insert adequate wall plugs into
the holes.
5. Turn the screws into the wall plugs in such a way
that about 40 mm of each screw still stick out.
6. Remove the station from the packaging.
7. Remove the insulating front shell.
8. Hang the domestic hot water module onto the
screws. Tighten the screws, so that the sides of the
insulation are flush to the wall.

6Mounting and installation [specialist]
16 99640x5xx-mub-en – V01 2020/06
9. Connect the domestic hot water module with the
installation by using the piping according to the
adjacent figure.
1
Primary side:
Return to the buffer tank,
Connection
FriwaMidi:
1½" external thread,
Connection
FriwaMaxi:
2" external thread,
Piping:
FriwaMidi: min. DN 25, 28 x 1.5 mm,
FriwaMaxi: min. DN 32, 35 x 1.5 mm,
maximum length 2 m
2
Secondary side:
Hot water circulation, return,
connection: 1" external thread, flat sealing
3
Secondary side:
cold water inlet,
connection
FriwaMidi:
1" ext. thread, flat-sealing
connection
FriwaMaxi
: 1¼" ext. thread, flat-sealing
4
Secondary side:
hot water outlet,
connection
FriwaMidi
: 1" ext. thread, flat sealing
connection
FriwaMaxi
: 1¼" ext. thread, flat-sealing
5
Primary side:
flow from the buffer tank,
connection
FriwaMidi
: 1½" external thread,
connection
FriwaMaxi
: 2" external thread,
Piping:
FriwaMidi: min. DN 25, 28 x 1.5 mm,
FriwaMaxi: min. DN 32, 35 x 1.5 mm,
maximum length 2 m
Pipe distance to the wall
(primary) = 95 mm
Pipe distance to the wall
(secondary) = 167 mm

7Commissioning [specialist]
2020/06 99640x5xx-mub-en – V01 17
7Commissioning [specialist]
NOTICE
Slowly
open the valves in the pipes and in the module, in order to prevent pressure surges.
Functioning check valve
The ball valves (A) and (N) in the primary circuit are
equipped with a check valve, in order to avoid
unwanted gravity circulation.
To vent and flush the installation, the check valves
must be open. For this purpose, turn the ball valves
into the position
45°
.
The check valve is not operating.
For the operation of the installation, all (ball) valves
must be
completely
open (position
0°
).
Position 0°
Position 45°
Position 90°
Check valve in operation,
through-flow in flow direction
only.
Check valve not in operation,
through-flow in both directions.
Ball valve closed,
no through-flow.
1

7Commissioning [specialist]
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7.1 Filling the primary circuit
WARNING
Danger of scalding due to hot water!
The system is under pressure. By opening the vent valve, hot water with a
temperature of up to 90 °C may exit and cause personal injury.
Open the vent valve slowly and with sufficient distance.
If the storage tank is (partly) filled
1. Slowly open the ball valve (N) by turning it to
position
0°
.
2. Fill the storage tank using the fill valves available on
site until an operating pressure of about 1.5 bars* is
reached. Use heating water compliant with the
standards VDI 2035 / ÖNorm H5195-1.
3. Manipulate the vent valve (L) cautiously to let the air
escape.
5. Close the vent valve (L).
6. Close the ball valve (N) by turning it into
position
90°
.
7. Check the operating pressure of the storage tank
after the venting and increase the pressure if
necessary.
8. Open the ball valves (A) and (N) completely by
turning them into position
0°
.
Primary circuit
* 1.5 bars in the primary circuit = recommended minimum value
The pressure also depends on the individual system pressures and on the components of the heating
installation!

7Commissioning [specialist]
2020/06 99640x5xx-mub-en – V01 19
7.2 Commissioning of the controller
WARNING
Risk to life and limb due to electric shock!
Check whether the sensors and pumps have been connected to the
controller and the controller housing is closed.
Only under these circumstances, the mains plug of the controller can be
plugged into a socket.
1. Connect the domestic hot water module to the
mains (230 V, 50 Hz) by using the premounted
connection cable.
2. Carry out the commissioning of the controller
(see controller instructions, chapter
Commissioning ). After that, start the pump in the
automatic/manual mode (PWM signal = 100 %,
see controller instructions chapter
Automatic/manual mode ).
3. Let the pump run for several minutes to vent the
domestic hot water module.
4. If the air noises do not stop, carefully manipulate
the vent valve (L) while the pump is still running
and let the air escape.
5. If the air noises have stopped, the pump can be
switched off.
6. To do so, in the automatic/manual mode, set the
pump to "Automatic".
7. Slowly open the piston valves (F) and (G) on the
secondary side.
Primary circuit
Secondary circuit

7Commissioning [specialist]
20 99640x5xx-mub-en – V01 2020/06
8. Open a withdrawal point for domestic hot water
(for example a tap) with a flow rate of at least
10 l/min and let the water run for about 2 minutes
to vent the secondary circuit. Close all withdrawal
points of the secondary circuit afterwards.
9. Make sure that the domestic hot water module is
correctly integrated into the potential equalisation
of the installation.
10. The FriwaMidi / FriwaMaxi is now ready for
operation.