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ML - SERIES BOILER
The Strebel ML Condensing Boiler
Strebel the prestige name in Heating Technology
introduce the result of further technical evolution - the
Gas fired ML floor standing Condensing Boiler. The
ML Boiler construction ensures that all parts that are in
contact with the Burner flame and combustion products
are made of AISI 316 Ti stainless steel, which has a
first class capability of resisting the attacks from acid
condensate.
The ML has a very high efficiency (max.109%) which
places it at the peak of the classification according to
European Output Directive 92/42/EEC.
The yearly saving between a traditional type of boiler
and a condensing boiler is up to 15%. Direct boiler
compensation and control of the plant temperature
favours operation at low temperatures, therefore
allowing up to a further 20% increase of the overall
efficiency. When considering the replacement of old
boiler technology, which have an average efficiency
of less than 82%, the fuel saving could reach a
phenomenal 40%.
Efficiency and Emissions
The reasons for this high efficiency are:
• Recovery of the latent heat by
condensation of the water vapour present in the flue gases.
• Extremely low flue temperature,
equal to that of the return water
plus about 10°C.
• Reduction to a minimum of heat loss
through the boiler casing.
• Medium and Low temperature
return connections.
High energy saving and low pollution emission are the ML
Boilers’ best characteristics.
The emission of polluting substances produced during
the combustion process consists of carbon monoxide
and nitrous oxide. EEC Directives set ever more stringent
permissable values of these green house gasses. The ML
boiler range falls easily within the limits set by European
Directives, the uncompromising Swiss regulations, and also
the “Blue Angel” ecological mark.
The emissions of nitrous oxide and dioxides, commonly
known as NOx, are linked to high flame temperatures and
the length of time that the combustion products remain in a
boiler furnace. The ML furnace is sized to prevent high heat
concentration and therefore reduce the flame temperature;
it also has particular geometry to facilitate the rapid
evacuation of combustion products. The excellent ecological
characteristics of the combustion chamber can be further
enhanced by coupling the boiler to a premix burner or
special pressure jet burner.
ML-SERIES BOILER
ML Condensing Boiler structure.
The boiler body is composed of two essential
structures, the first being a horizontal cylindrical
furnace where flue gases begin to condense, and
secondly, a vertical condensing section with an inner
corrugated surface shape capable of increasing the
heat exchanging surface area and flue gas turbulence.
The tapered moulding of the surfaces facilitate the
development of drops of condensate guaranteeing
adequate drainage.
The combustion of 1m3 of natural gas
produces 1.6kg of water. To convert
the water vapour in the flue gas into
energy it is necessary to condense it
on a sufficiantly cold heat exchanger
surface (Max. 58°C) which in turn
releases the latent heat.
Condensing Boilers and Heating Systems
STREBEL ML Condensing boilers are ideally suited to
low temperature systems, such as large surface area
radiators or underfloor heating systems in which the
return water temperature is lower than 60°C.
However, the ML Boiler also offers the possibility of
working with mixed temperature systems, that is, low
and medium temperature, without detracting from its
efficiency. The boiler may in fact be connected to two
circuits operating at different temperatures as there are
two return connections; one for low temperature, such
as underfloor heating, radiators with large surface
areas etc. and another connection for medium to
high temperature circuits such as hot water cylinders,
convectors and ordinary radiators.
The efficiency never falls below the threshold of 96%,
therefore guaranteeing constant operating economy
and low pollution.
ML-SERIES BOILER
160 / 270
70 / 125
350 / 670
B
A
B
A
N1
B
N1
H
N3
N3
N2
øiC
øiC
N2
B1
B1
Technical Data
N3
N2
øiC
H
Mod.
210-270
H
A
Flow/Return
Temp.
Units
80/60°C
B1
ML Boiler Model
75
95
125
160
210
270
350
440
550
610
670
kW
87
110
145
186
244
313
406
511
639
709
779
50/30°C
kW
96
122
161
206
270
348
451
566
708
786
863
80/60°C
kW
29
37
48
61
81
104
136
170
212
236
259
50/30°C
kW
33
42
55
69
91
117
152
191
238
264
290
80/60°C
%
97
97
97
97
97
97
97
97
97
97
97
50/30°C
%
107.5
107.5
107.5
107.5
107.5
107.5
107.5
107.5
107.5
107.5
107.5
80/60°C
%
97.3
97.3
97.3
97.3
97.3
97.3
97.3
97.3
97.3
97.3
97.3
50/30°C
%
109
109
109
109
109
109
109
109
109
109
109
Max. Flue Gas Temp.
80/60°C
°C
80
80
80
80
80
80
80
80
80
80
80
(air T=20°C)
50/30°C
°C
45
45
45
45
45
45
45
45
45
45
45
Water Content
Litres
150
210
200
308
285
340
392
560
523
523
523
Hydraulic Resistance (Δt=12°C)
mbar
8
12
22
12
22
16
11
17
27
34
41
Max. Working Pressure
bar
4
4
4
4
4
4
5
5
5
5
5
Boiler Weight
kg
220
280
320
520
590
680
1030
1230
1270
1270
1270
Min. Gas Flow Rate (Nat.Gas G20)
m³/hr
9.51
12.05
15.86
20.29
26.64
34.26
44.4
55.81
69.77
77.38
84.99
NOx (approx.)
ppm
30
30
30
30
30
30
30
30
30
30
30
CO (approx.)
ppm
5
5
5
5
5
5
5
5
5
5
5
A
mm
936
963
963
1060
1060
1060
1198
1198
1198
1198
1198
B**
mm
990
1330
1330
1550
1550
1801
1817
2331
2331
2331
2331
B1
mm
670
1010
1010
1004
1004
1254
1205
1720
1720
1720
1720
H
mm
1825
1825
1825
2151
2151
2200
2310
2310
2310
2310
2310
ØiC
mm
150
180
180
200
200
200
250
250
250
250
250
DN
50
50
50
65
65
80
100
100
100
100
100
Rated working power
Min. working power
Working Efficiency (full load)
Working Efficiency (30% load)
Dimensions
Connections
N1/N2/N3
** dimensions given do not allow for the burner projection when burner is fitted. Please refer to burner literature for the burner projection dimensions.
10/2008 - The Company reserves the right to change the specification and dimensions without prior notice.
Strebel Ltd. • 1F, Albany Park Industrial Estate Frimley Road, Camberley, Surrey, GU16 7PB
[email protected] • www.strebel.co.uk • Tel: +44 (0)1276 685 422 • Fax:+44 (0)1276 685 405