Service mode › Atag

Atag boiler service mode

How to put an Atag boiler into service mode, so it holds maximum or minimum rate while you take combustion readings. 41 models from 10 Atag installation and servicing manuals, each step with the page it came from.

Grouped by manual: one manual usually covers a range of outputs. The CO₂ figures are the manual's own. Set and check them with a calibrated analyser, never by eye.

A200SOV Open vent heat only boiler

Covers: Sov.

GC 41-310-15

Accessing Parameter Settings (Service Mode)

  1. Press the OK key for 3 seconds. Display shows 'P6 81'.
  2. Press the OK key for 3 seconds again. Display shows 'on' followed by 'P5 18'.
  3. Use Scroll keys to browse parameters.
  4. Press OK to select/change a parameter.
  5. Adjust value using + or - keys.
  6. Press OK to confirm new setting.
  7. Press ESC to exit to standard display.

From manual 8G.51.70.02/08.11, page 24.

Force Maximum Rate (for O2 Checking)

  1. Set external controls to call for heat.
  2. Ensure boiler is operational and able to dissipate heat.
  3. Press both + keys for 6 seconds.
  4. The display shows the supply water temperature (blinking) and the boiler switches to maximum heating capacity.
  5. To terminate, press the ESC key (- key).

From manual 8G.51.70.02/08.11, page 27.

GasCO₂ max rateCO₂ min rateCO max
Natural gas9%––

CO₂ and CO from manual 8G.51.70.02/08.11, page 31. Check against the data badge.

The boiler requires no adjustment of the burner pressure and quantity, because it is self-regulative and has been set in the factory and should not be reset. Only in case of a failure or when replacing the gas block, venturi and/or fan, the O2 percentage should be checked. (page 23)

ATAG A-Series

Covers: A200S, A320S, A325C, A325ECX

GC 41-310-14, 41-310-17, 47-310-17, 47-310-18

Force maximum heating capacity for O2 / combustion check

  1. Set the external controls to call for heat.
  2. Make sure the boiler is operational and can get rid of the heat it produces.
  3. Calibrate the O2 gauge.
  4. Place the lance of the O2 gauge into the flue gas test point.
  5. Press both + keys for 6 seconds.
  6. The display shows the supply water temperature (blinking); the boiler will immediately switch to the maximum heating capacity.

From manual 8G.51.59.05/08.11, page 33.

Entering Parameter Menu (Service settings)

  1. Press the OK key for 3 seconds. The display shows 'P6' alternated with '81'.
  2. Press the OK key for 3 seconds again. The display shows 'on' shortly followed by 'P5 18'.
  3. Use the Scroll keys to browse through the parameters, use OK to select/confirm, and use + or - to adjust values.

From manual 8G.51.59.05/08.11, page 29.

The boiler requires no adjustment of the burner pressure and quantity, because it is self-regulatory and has been set in the factory and should not be reset. (page 28)

ATAG E-Series

Covers: E Range, E22c

GC 41-310-12, 41-310-13, 47-310-13, 47-310-14

Entering Service Mode / Installer Level

  1. Press the Mode-key for 5 secondss.
  2. Press by means of the + or the - key until the code C123 is shown;
  3. Press the STORE-key to confirm the code (code blinks1 x).
  4. Press briefly the MODE-key to select one of the 4 chapters, i.e. PARA;
  5. Press once or more briefly on the STEP-key to select a Parameter
  6. Alter the value, if necessary/possible, by means of the + or the - key
  7. Press briefly on the STORE-key to confirm the alteration.
  8. Press once or more on the MODE-key until StBY or Good is shown:

From manual 8G.51.60.00/03.07, page 25.

Forcing Maximum and Minimum Rate (CO2 / Fan Check)

  1. - Press the Central Heating and DHW buttons once to ensure that the boiler is OFF and not firing.
  2. - Press the MODE-key for 5 seconds.
  3. - The display will show COdE followed by an arbitrary number;
  4. - Select by means of the + or the - key the code C123;
  5. - Press the Store-key to confirm the code (code blinks 1 x);
  6. - Press the MODE-key until SERV is shown;

From manual 8G.51.60.00/03.07, page 28.

The boiler settings, such as burner pressure and adjustment of the air quantity are unnecessary, due to the fact that the boiler operates with a so-called zero pressure control. This means the correct gas quantity is controlled by the suction operation of the fan. The fine adjustment which is carried out at the factory is one off, which means that adjusting of these values is unnecessary. Only when replacing the gas valve, venturi and/or the fan, does the zero pressure and the incorrect CO2 adjustment have to be checked and, if necessary, adjusted to the correct value. (page 28)

ATAG iC-Range (manual 8G.51.80.00 / 03.15)

Covers: iC 24 47-310-19 iC 24 LPG, iC 36 47-310-23 iC 36 LPG, iC 40 47-310-25 iC 40 LPG, iC Economiser 27, iC Economiser 39, iC28, iC36, iC40

GC 47-310-20, 47-310-21, 47-310-22, 47-310-23, 47-310-24, 47-310-25, 47-310-26, 47-310-27, 47-310-28, 47-310-31, 47-310-32

Enter commissioning / maximum rate mode (Checking CO2)

  1. Set the external controls to call for heat.
  2. Make sure the boiler is operational and can get rid of the heat it produces.
  3. Calibrate the flue gas analyser.
  4. Place the lance of the flue gas analyser into the flue gas test point.
  5. Press both + buttons for 6 seconds.
  6. When the flame symbol appears in the display press both + buttons again for 6 seconds.
  7. The display shows the supply water temperature and the boiler will switch to maximum power of the heating capacity.
  8. Press 1x the eco-button; the display shows the heating capacity percentage.

From manual 8G.51.80.00 / 03.15, page 41.

Force minimum rate (Low load CO2 check)

  1. Press on the - button until the minimum value (0%) has been reached (low load).

From manual 8G.51.80.00 / 03.15, page 42.

Exit service / commissioning mode

  1. Press the ESC button. The device switches off and the display shows for 2 seconds code 180 or 181.

From manual 8G.51.80.00 / 03.15, page 42.

ModelGasCO₂ max rateCO₂ min rateCO max
iC 24 47-310-19 iC 24 LPG, iC 36 47-310-23 iC 36 LPG, iC 40 47-310-25 iC 40 LPG, iC Economiser 27, iC36, iC40Natural gas9.0% (-0.4 / +0.6)––
iC 24 47-310-19 iC 24 LPG, iC 36 47-310-23 iC 36 LPG, iC 40 47-310-25 iC 40 LPG, iC Economiser 27, iC36, iC40LPG10.3% ± 0.6%––
iC Economiser 39, iC28Natural gas9.0% (-0.4 / +0.6)9.0%–
iC Economiser 39, iC28LPG10.3% ± ( 0.6%)––

CO₂ and CO from manual 8G.51.80.00 / 03.15, page 41. Check against the data badge.

The boiler requires no adjustment of the burner pressure and quantity, because it is self-regulatory and has been set in the factory and should not be reset. (page 36)

ATAG iC-Range (manual 8G.51.84.01 / 03.19)

Covers: i24C, i28C, i40C, iC Economiser 27 Plus, iC Economiser 35 Plus, iC Economiser 39 Plus

GC 47-310-36, 47-310-37, 47-310-39, 47-310-40, 47-310-41, 47-310-42

Enter Service Mode (Chimney Sweep Function / High/Low Fire & CO2)

  1. Press the chimney sweep button on the control panel for 5 seconds.
  2. Turn the selector wheel to reach 100% for full load (high fire) or 0% for low load.
  3. Press OK.

From manual 8G.51.84.01 / 03.19, page 55.

Exit Service Mode

  1. Press the back button for 5 seconds to exit chimney sweep mode.

From manual 8G.51.84.01 / 03.19, page 56.

GasCO₂ max rateCO₂ min rateCO max
Natural gas9.0%8.6%350 ppm
LPG10.3%9.9%–

CO₂ and CO from manual 8G.51.84.01 / 03.19, page 55. Check against the data badge.

The air gas ratio valve is factory set and must not be adjusted during commissioning unless this action is recommended following contact with the manufacturer. (page 58)

ATAG iR-Range

Covers: i15R, i18R, i24R, i32R, i40R

GC 41-310-49, 41-310-50, 41-310-51, 41-310-52, 41-310-53

Enter Service Mode (Chimney Sweep Function)

  1. Press the chimney sweep button for 5 seconds.
  2. Turn the selector wheel until you reach 100% for full load or 0% for low load.
  3. Press OK.

From manual 8G.51.85.01 / 03.19, page 46.

Exit Service Mode

  1. Press the back button for 5 seconds to exit chimney sweep mode.

From manual 8G.51.85.01 / 03.19, page 47.

ModelGasCO₂ max rateCO₂ min rateCO max
i15R, i18R, i24R, i32RNatural gas9.0%8.6%350 ppm
i15R, i18R, i24R, i32RLPG10.3%9.9%350 ppm
i40RNatural gas9.0% ± Minimum 8.6%, maximum 9.6%9.0%350 ppm
i40RLPG10.3% ± Minimum 9.9%, maximum 11.0%10.3%350 ppm

CO₂ and CO from manual 8G.51.85.01 / 03.19, page 46. Check against the data badge.

The air gas ratio valve is factory set and must not be adjusted during commissioning unless this action is recommended following contact with the manufacturer. (page 49)

ATAG iS-Range (manual 8G.51.82.03 / 01.16)

Covers: iS 12, iS 12 41-310-18 iS 12 LPG, iS15, iS18, iS24, iS40

GC 41-310-18, 41-310-19, 41-310-20, 41-310-21, 41-310-22, 41-310-23, 41-310-24, 41-310-25, 41-310-28, 41-310-29

Enter Commissioning/Service Mode for CO2 check

  1. Set the external controls to call for heat.
  2. Make sure the boiler is operational and can get rid of the heat it produces.
  3. Calibrate the flue gas analyser.
  4. Place the lance of the flue gas analyser into the flue gas test point.
  5. Press both + buttons for 6 seconds.
  6. When the flame symbol appears in the display press both + buttons again for 6 seconds.
  7. The display shows the supply water temperature and the boiler switches to maximum power of the heating capacity.
  8. Press 1x the eco-button; the display shows the heating capacity percentage.
  9. To check low load, press on the - button until the minimum value (0%) has been reached.

From manual 8G.51.82.03 / 01.16, page 44.

Exit Service Mode

  1. Press the ESC button (ESC / - button).
  2. The device switches off.
  3. The display shows for 2 seconds code 180 or 181.

From manual 8G.51.82.03 / 01.16, page 45.

GasCO₂ max rateCO₂ min rateCO max
Natural gas9.0% (-0.4 / +0.6)–350 ppm
LPG10.3% ± ( 0.6%)–350 ppm

CO₂ and CO from manual 8G.51.82.03 / 01.16, page 44. Check against the data badge.

The air gas ratio valve is factory set and must not be adjusted during commissioning unless this action is recommended following contact with the manufacturer. (page 46)

ATAG iS-Range (manual 8G.51.86.01 / 03.19)

Covers: i15S, i18S, i24S, i40S

GC 41-310-44, 41-310-45, 41-310-46, 41-310-48

Enter Service Mode (Chimney Sweep Mode) for CO2 Check

  1. Press the chimney sweep button for 5 seconds.
  2. Turn the selector wheel until you reach 100% for full load, or 0% for low load.
  3. Press OK to activate the selected rate.

From manual 8G.51.86.01 / 03.19, page 56.

Exit Service Mode

  1. Press the back button for 5 seconds to exit chimney sweep mode.

From manual 8G.51.86.01 / 03.19, page 57.

GasCO₂ max rateCO₂ min rateCO max
Natural gas9.0%–350 ppm
LPG10.3%––

CO₂ and CO from manual 8G.51.86.01 / 03.19, page 8, 56. Check against the data badge.

The air gas ratio valve is factory set and must not be adjusted during commissioning unless this action is recommended following contact with the manufacturer. (page 59)

ATAG Premier E-SHR series

Covers: Premier

GC 47-310-01, 47-310-02

Force Max/Min Rate for CO2 Check

  1. In Service Mode Step 1, adjust to maximum load by means of the '+' key.
  2. Identify minimum load by pressing the '-' key until minimum is reached.
  3. Press '-' key again while at minimum to turn selection 'Off'.

From manual 8G.51.18.01/07.04, page 22.

GasCO₂ max rateCO₂ min rateCO max
Natural gas9%––
LPG10.5%––

CO₂ and CO from manual 8G.51.18.01/07.04, page 24. Check against the data badge.

The boiler does not require adjustment of the burner pressure and air quantity because it is self adjusting and is factory set at the correct value. The fine adjustment which is carried out at the factory is once-only, which means that adjusting of these values is unnecessary. (page 17)

ATAG Q

Covers: Q 25S, Q 30CR, Q25SC, Q38SC

GC 41-310-08, 41-310-09, 41-310-10, 41-310-11, 47-310-10, 47-310-11, 47-310-12

Entering Installer Level / Service Adjustments

  1. Press the Mode-key for 5 secondss. The display shows COdE followed by an arbitrary number;
  2. Press by means of the + or the - key until the code C123 is shown;
  3. Press the STORE-key to confirm the code (code blinks1 x).
  4. Press briefly the MODE-key to select one of the 4 chapters, i.e. PARA;
  5. Press once or more briefly on the STEP-key to select a Parameter (parameter visible on the left, value on the right) ;
  6. Alter the value, if necessary/possible, by means of the + or the - key
  7. Press briefly on the STORE-key to confirm the alteration. When you have to change more values, repeat from step 5.
  8. Press once or more on the MODE-key until StBY or Good is shown: After a few seconds the text StBY will be replaced by the technical read-out or Good-state (Depending from the position the acces code is keyed in)

From manual 8G.51.40.00/03.06, page 27.

Forcing Max & Min Rate (Zero Pressure / CO2 Check Mode)

  1. Access installer level using code C123 via the MODE key.
  2. Navigate to chapter SERV using the MODE-key.
  3. Press the STEP-key once until 1 is shown (alternately 1 and OFF).
  4. Press the + key until the maximum value is achieved (boiler burns on full load, value displayed in kW).
  5. Press the - key until the minimum value is achieved for minimum rate, or keep pressed until OFF is shown to exit.

From manual 8G.51.40.00/03.06, page 30.

The boiler settings, such as burner pressure and adjustment of the air quantity are unnecessary, due to the fact that the boiler operates with a so-called zero pressure control. This means the correct gas quantity is controlled by the suction operation of the fan. The fine adjustment which is carried out at the factory is once-only, which means that adjusting of these values is unnecessary. Only in case of replacing of the gas valve, venturi and/or fan the zero pressure and the incorrect CO2 adjustment has to be checked and, if necessary, adjusted at the right value. (page 30)

The app

Every Atag manual, searchable on the job

Service mode, gas valve and combustion figures, fault codes and the full manual for the boiler in front of you, plus Ask Flint for anything the manual covers.

Start 7 days free

Then £3.99 a month or £29.99 a year. Cancel any time.

Common questions

Is service mode the same as chimney sweep mode?

Yes, in practice. Makers use different names for the same function: service mode, chimney sweep mode, test mode, calibration mode, check programme. Each one holds the burner at a fixed rate, usually maximum then minimum, so you can take a stable combustion reading.

Can I adjust the gas valve while it's in service mode?

Only where the manual gives an adjustment procedure, and only with an analyser in the flue. Many current boilers are set at the factory and the manual says not to touch the gas valve. Where a manual says that, it is shown with the procedure above.

Other makers

AlphaAristonBaxiBiasiChaffoteauxFerroliGlow-wormHalsteadHeatlineIdealIntergasJohnson StarleyKestonMainPottertonRemehaSimeVaillantViessmannVokeraWorcester Bosch

Service mode and combustion checks are work for a competent, Gas Safe registered engineer. These procedures are taken from the manufacturers' manuals and inform your judgement; they don't replace it. Always work to the manual for the exact appliance, its data badge and the current standards.