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Alpha E-Tec Plus combi (28, 33)

Combi, natural gas and LPG (LPG by conversion kit)

Combustion figures

FigureNatural gas (G20)LPG (G31)
CO₂ at high rate
More infoHide infoFigures are CO₂ at maximum DHW output: chimney sweep mode at 99% (max DHW output), case fitted, analyser in the flue test point. MI 3.1/3.2 also list CO₂ at maximum CH output (NG 28: 9.7%, 33: 9.5%; LPG 28: 11.4%, 33: 11.2%, no tolerance given), but MI 6.6 says CO₂ testing at max CH output is not required.
28
9.7% (+0.5/−0.2%)
33
9.5% (±0.2%)
28
11.4% (+0.1/−0.3)
33
11.2% (+0.2/−0.4)
CO₂ at low rate
More infoHide infoChimney sweep mode at 0% (low fire), case fitted.
28
8.8% (+0.2/−0.3%)
33
8.6% (+0.2/−0.3%)
28
10.6% (+0.3/−0.1)
33
10.0% (+0.4/−0.2)
Maximum CO
More infoHide infoRate not stated in MI. The LPG table (MI 3.2) gives no CO figure but says other technical data is the same as NG data.
450 ppm450 ppm
CO/CO₂ ratio
More infoHide infoMI 7 says if the ratio is above 0.004, check for recirculation, flue blockage and gas supply, then clean the burner and retest. LPG figure from the MI 3.2 note that other technical data is the same as NG data.
0.0040.004
O₂
Not given in MINot given in MI
Working inlet pressure
More infoHide infoMeasurement point not stated in MI. Given as Gas supply pressure in MI 3.1/3.2, a single figure with no range. MI 7 says to check the working gas inlet pressure at maximum rate.
20 mbar37 mbar
Gas rate at maximum
28
3.05 m³/h
33
3.45 m³/h
28
2.24 kg/h (0.62 g/s)
33
2.53 kg/h (0.70 g/s)

From Part No. 1.042373 rev. ST.003780/000 (0918/D387)

Enter service mode for high and low rate

High rate

  1. With no heating or hot water demand, hold RESET for 8 seconds. The parasol and snowman symbols flash together.
  2. If a Climatic controller is fitted it shows ERR>07. That’s not a fault.
  3. Press DHW up to step up to 99% (maximum). The levels are 0%, 80–90% and 99%.

Low rate

  1. Press DHW down to set the output to 0% (minimum).
  2. Press DHW up to go back to maximum.
Ending the test
  • Turn the boiler off to come out: hold the Off/Stand-by/Summer/Winter button for 8 seconds. It also ends by itself after 15 minutes.

Models and GC numbers

ModelGC numberGas
E-Tec Plus 2847-532-77NG
E-Tec Plus 3347-532-78NG

Source: Alpha E-Tec Plus 28 and 33 Installation and Servicing Instructions, Part No. 1.042373 rev. ST.003780/000 (0918/D387).

Sections: 3.1 Technical performance data - natural gas; 3.2 Technical performance data - LPG; 6.6 Checking the combustion - chimney sweep mode; 6.11 Converting the boiler to operate on LPG; 6.12 CO2 set up procedure; 7 Routine servicing (combustion check).

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Check these figures against the MI for the appliance in front of you, matched by GC number and manual date. Combustion work needs a calibrated analyser and a Gas Safe registered engineer.