Baxi Combi
224
228
424
428
Nominal heat output
50/30°C — Central Heating
— Maximum Rate
Pnc
kW
21.8
26.1
21.8
26.1
Nominal heat output
50/30°C — Central Heating
— Minimum Rate
Pnc
kW
5.2
5.2
5.2
5.2
Tab.6
Central heating circuit specifications
Baxi Combi
224
228
424
428
Maximum pressure
bar
3
3
3
3
Minimum pressure
bar
0.5
0.5
0.5
0.5
Central heating temperature adjust
ment ±5°C
°C
25/80
25/80
25/80
25/80
Expansion vessel water capacity
litres
7.0
7.0
7.0
7.0
Expansion vessel pre charge pres
sure
bar
1.0
1.0
1.0
1.0
Maximum capacity of central heat
ing system
litres
120
120
120
120
Primary water content of boiler (un
pressurised)
litres
2.5
2.5
2.5
2.5
Tab.7
Domestic hot water circuit specifications
Baxi Combi
224
228
424
428
Maximum pressure
bar
8.0
8.0
8.0
8.0
Dynamic minimum pressure
bar
0.5
0.5
0.5
0.5
Minimum working water flow rate
l/min
2.0
2.0
2.0
2.0
Specific flow rate (D)
l/min
11.5
13.4
11.5
13.4
Domestic hot water temperature
range adjustment ±5°C
°C
35/60
35/60
35/60
35/60
Production of domestic water with
ΔT = 30°C
l/min
11.4
13.3
11.4
13.3
Production of domestic water with
ΔT = 35°C
l/min
9.8
11.5
9.8
11.5
Where low flow taps or fittings are intended to be used in the DHW system connected to the boiler, it is strongly recommended
that the DHW flow rate DOES NOT fall below 2.5 l/min. This will ensure reliable operation of the DHW function.
Tab.8
Characteristics of combustion
Baxi Combi
224
228
424
428
Natural gas rate (G20) Qmax
m
3
/h
2.61
3.06
2.61
3.06
Natural gas rate (G20) Qmin
m
3
/h
0.52
0.52
0.52
0.52
Diameter of coaxial discharge
pipes
mm
60/100 & 80/125
60/100 & 80/125
60/100 & 80/125
60/100 & 80/125
Important
Dynamic (nominal) inlet pressure (Natural gas — G20) 20mbar
with a CV of 37.78 MJ/m
3
Tab.9
Electrical specifications
Baxi Combi
224
228
424
428
Nominal electrical power supply
voltage
V
230
230
230
230
Nominal electrical power supply
frequency
Hz
50
50
50
50
3 Technical specifications
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