30
Instructions for the installer
When there is a heat request from the E8 controller or from a
BCM (Boiler Cascade Manager), the E8 or BCM calculates
the necessary output
according to the difference between the
set temperature (or the temperature calculated by the outer
compensator) and the global flow temperature. The number
of thermal elements (each thermal element represents a ma-
ximum input of 110 kW) x 100% determines the maximum
input expressed in %.
When the input has been determined, the boiler pump (not
supplied by Unical) is set up and the fan of one thermal ele-
ment is set in motion at starting speed. The gas valve opens
and ignition is to occur within 5 sec. When the ionisation elec-
trode detects the flame, the thermal element starts operating.
Subsequently other thermal elements are likely to start in the
same way. One of the operation principles for this boiler is
letting as many burners as possible operate simultaneously
at minimum load to reach the maximum efficiency.
For example, if a 4 thermal element boiler is requested to
operate at its max input, this shall be 400% i.e. :
110 kW x 4 thermal elements = 440 kW = 400%.
If it is requested to operate at 200% input, thanks to the input
sharing system on the highest number of thermal elements,
each thermal element will operate at 50% output i.e. :
200% : 4 moduli = 50 %
corrispondente a 100 kW totali
ossia 25 kW per ciascun modulo.
Such principle provides clearly efficiencies much higher than
those obtained in traditional groups of small boilers installed
in cascade.
When the input shared on each thermal element is less than
12 kW
, one thermal element after the other is automatically
excluded and the remaining input
is shared on thermal
elements having the smallest number of operation hours (by
the automatic operation-time calculating system).
Modulation, i.e. input
reduction, is based on the difference
between the set temperature (or the temperature calculated
by the outer compensator) and the global flow temperature.
When no ignition occurs, the ignition device repeats two more
times the ignition sequence and then puts to lock out position
the thermal element concerned.
4 thermal elements of 50 kW each working
at 50% of the output give = 100 kW = (200%),
i.e. 25 kW / thermal element
0
5
10
15
20
25
30
35
40
kW
45
50
55
60
10
100
104
% (p.c.i.)
20
50
30
40
22
109,6
109
P
(kW)
60
70
80
90
100 108
50 % = 54 kW
1 thermal
elemets
100 % = 108 kW
54
1 thermal
elemets
400% : 200 kW = 200% : X
X = (432x200)
:
400 = 216 kW
input shared on 4
thermal elements
Input shared on 4 thermal elements : total input
= 216:432 = 0,5 = 50%
Efficiency of a thermal element working at full capacity
108 kW = 103,2 %
(in condensation)
Efficiency of a thermal element working at reduced
capacity
54 kW = 106,7 %
(in condesation)
Efficiency of a thermal element working at minimum
capacity
22 kW = 108,8 %
(in condesation)
All the thermal elements work in parallel at the same ou-
tput, equalizing, thus, the C.H. system efficiency to the one
of the thermal element.
1
Thermal element
(module) = 108 kW = 100%
4
Thermal elem.
= 108 kW x 4 = 432 kW = 400%
