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3. Technical description
3.3 Operating principle
Δp Pressure drop
Q
Water flow
3.3.1. Boiler pump
CAUTION
If the power consumption of the pump is more than
150 VA/1.3A, it must be connected to the SCU-S02
(Accessory)
The boiler is supplied without a pump. The proper
pump selection has to reflect the pressure drop and
system flow calculation which includes the DHW sizing.
Back flow preventer
A backflow preventer must be used in the cold water
supply piping when required by national or local codes
having jurisdiction.
Refer to the Technical Specifications on page 17.
If possible, install the pump directly under the boiler on
16
the return connection. The pump must be pumping into
the boiler.
Refer to chapter 4.5. Installation Examples,
( page 25 and 26.)
Recommended pumps for the MCA Pro boilers are:
•
Taco
•
Wilo
•
Grundfos
See chapter: 4.10.3 "Connection possibilities for
the PCB (SCU-S02)", page 61
3.3.2. System in cascade
The boiler is ideally suited for a cascade system. There are
a number of standard solutions available. For example:
•
Cascade systems (quick assembly) for the
installation of 2 to 6 boilers next to each other or
3 to 6 boilers mounted back to back on a free-
standing frame. When the boilers are mounted
next to each other, they can be mounted either on
the wall or on a freestanding frame. The wall or
the frame must be able to bear the weight of the
boilers and must be sufficiently stable.
•
Hydraulic separators/Low loss headers for a
cascade system of 2 or 3 boilers (MCA Pro 45
and/or MCA Pro 65). The supply and return of each
boiler can be directly connected to these.
i
Please contact us for further information.
3.3.3. DHW tank connection
An indirect DHW tank can be connected to an individual
boiler. The DHW tank can be connected to the boiler in
two ways:
•
Using a three-way diverting valve.
•
Using a DHW tank pump.
3.3.4. Water flow rate
The minimum and maximum waterflow, as listed on
the next page should be taken into account to protect
the boiler for to low- or high waterflow / temperature
differences in the heat exchanger.
The boiler's modulating control system limits the
maximum difference in temperature between the
heating supply and return and the maximum speed
at which the supply temperature increases, this could
cause a reduction of heat output of the boiler.
MCA Pro 45/65/90/115
MCA-Pro ISM Rv.4.1 2/2017
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