Before Installation; Installation Requirements; Points To Consider For Boiler Replacement; Cascade System Structures - DeDietrich Innovens MCA 160 Manual

4 Before installation

4 Before installation
4.1

Installation requirements

12 MCA
4.1.1

Points to consider for boiler replacement

If the boiler output is reduced, the water flow rate will need to be adjusted
accordingly. Imagine that 4 MCA 160 boilers are connected in a cascade.
The total water flow rate is then 4 x 6.38 = 25.5 m
water is now pumped around the system at 32.7 m
loss header from the return to the supply line at 7.42 m
system is then 25.5/32.7 times as great as on the boiler side. If the boilers
heat to 90/70° C, the system then heats with a supply temperature of +/-
85° C. Most heat-output elements (such as radiators) have an exponential
curve. This means that a lower supply temperature results in much less
heat output. This can lead to complaints about the cold. The solution is to
match the flow rate in the system to the flow rate in the boilers. A lower
supply temperature is then worse than a lower water flow rate, especially
for the heat-output elements, where a high water temperature is required.
4.1.2

Cascade system structures

The return, flow, and gas connections of the individual boilers are connec­
ted using the fittings supplied by means of horizontal connections to main
pipes for return, flow and gas. These pipes are welded onto a frame that
rests on the floor and is fixed to the wall or to a free-standing frame. The
low-loss header supplied has flange connections, which can be fitted to
the left or right of the cascade main pipe as required. The blind flanges
supplied are then fitted on the other side. The gas main pipe has a flange
to which the optional gas filter can also be connected on the left or right as
required. When a gas filter is used, a pressure drop of 3 mbar over the gas
filter must be taken into account. The minimum gas pressure after the gas
filter is 20 mbar for L gas and 17 mbar for H gas. A common PVC con­
densed water discharge pipe (not supplied) can be installed in the frame.
For this purpose, holes have been made in the frame into which this pipe
can be fitted (to the left or right as required) sloping downwards.
Important
Any mix of MCA 160 and MCA 45-115 boilers is possible. This
manual focuses on the combination of MCA 160 boilers. Separate
cascade systems are available for combination consisting exclu­
sively of MCA 45-115 boilers.
See table for outputs of the different boilers.
Tab.1 Boiler outputs
Boiler type Nominal output [kW]
50/30° C
MCA 45-115 45 43
MCA 45-115 65 65
MCA 45-115 90 89.5
MCA 45-115 115 114
MCA 160 157
3
/h (at ΔT= 20° C). If the
3
/h, it flows in the low-
3
/h. The ΔT in the
80/60° C
40
61
84.2
107
148
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