Technical data
Graph of boiler residual head
flow rate l/h
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300
100
200
300
400
500
1
1
24 kW model
2 28 kW model
3 31 kW model TBA
2
SCHEMATIC
TECHNICAL DATA
24 MFFI 28 MFFI 31 MFFI
Separation of
the air intake
Simplified Coaxial
system coupling
Access to air
pressure switch
Category II 2H3+ II 2H3+ II 2H3+
Type C* C* C*
POWER
Heat input min. kW-Btu/h 11.0-37,500 12.0-40,900 14.0-47,700
Heat input max. k
W-Btu/h 26.5-90,400 30.2-103,000 33.5-114,300
Heat output min. kW-Btu/h 10.0-34,100 10.7-36,500 12.6-43,000
Heat output max. kW-Btu/h 24.6-83,900 28.1-95,800 31.0-105,800
EFFICIENCY
SEDBUK Rating Band
DDD
CHARACTERISTICS
Heat loss to the casing (
∆
T= 50°C) %
0.1 0.4 1.1
Heat loss through the flue when burner on % 6.9 67 6.5
Heat loss through the flue when burner off % 0.4 0.4 0.4
Maximum exhaust discharge (Natural Gas) kg/h 61.9 65.0 74.3
Residual discharge head mbar 1.65 1.40 1.60
Consumption at nominal capacity G20
(1)
m
3
/h 2.80 3.19 3.54
Consumption at nominal capacity
G30-G31
(1)
kg/h 2.09/2.06 2.38/2.34 2.64/2.60
Exhaust gas temperature at nominal capacity
°C 117.6 123.8 132.1
Minimum ambient temperature °C 5 5 5
Pressure loss through boiler (max) (∆T=20°C)
mbar 200 200 200
Residual head of system bar 0.25 0.25 0.25
D.H.W. minimum flow rate l/min 2.5 2.5 2.5
Domestic hot water pressure maximum bar 6 6 6
Domestic hot water pressure minimum bar 0.2 0.2 0.2
Built-in expansion vessel capacity l 6 6 6
Built-in expansion vessel pre-charged vessel bar 1 1 1
Maximum water content of system l 130 130 130
Maximum heating pressure
bar 3 3 3
Gas inlet pressure - Natural gas (G20) mbar 20 20 20
Gas inlet pressure - LPG (G30-G31) mbar 28-30/37 28-30/37 28-30/37
Weight kg 31 34 TBA
G.C. number 47-116-25 47-116-26 47-116-27
PERFORMANCE
Central heating temperature maximum °C 82 82 82
Central heating temperature minimum °
C 38 38 38
D.H.W. temperature maximum °C 56 56 56
D.H.W. temperature minimum °C 36 36 36
D.H.W flow rate
∆T =35°C l/min 10.1 11.5 12.7
D.H.W flow rate
∆T =35°C gal/min 2.2 2.5 2.8
ELECTRICAL DATA
Electrical supply V/Hz
230/50 230/50 230/50
Power consumption W 125 148 165
Protection grade of electrical system IP X4D X4D X4D
Internal fuse rating FAST 2 AT FAST 2 AT FAST 2 AT
C*: C12, C32, C42, C52, C82;
(1)
:15°C, 1013 mbar
*Calculated at 70% maximum output
Flue
connector
Air intake
(Twin flue)
Fan
Combustion
chamber
hood
Main heat
exchanger
Safety
thermostat
Combustion
chamber
Detection
electrodes
Ignition
electrodes
Motorised
diverter valve
DHW
temperature
probe
Gas
valve
Spark
generator
DHW flow
switch
Combustion
analysis
intake
Air pressure
switch
Venturi
tubes
Expansion
vessel
3 bar safety
valve
circulation
pump with
automatic air
release valve
MICROGENUS II 31 MFFI
mbar
ROOM-SEALED FAN FLUE
24 MFFI - 28MFFI - 31 MFFI
C.H. flow
temperature
probe
C.H. return
temperature
probe
Insulated
secondary
heat
exchanger
Pump
pressure
switch
Burner
Unit 3A, Thornton Road Ind. Estate Off Hockney Road Bradford, BD8 9HQ
01274 488 388
www.heatingspares247.com
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