"Best boiler on the market for build quality and hot water performance."
John Nicholson, ATAG Selected Partner
"Love the Wi-Fi control system! Great installation. Quick & clean"
Mr Carpenter


We've been doing this some time now, so based on experience we think we might be able to answer some of your questions below. However, if we've missed something, let us know.

How do I buy an ATAG boiler?

Q: How do I buy an ATAG boiler?

To help keep UK homes safe, we only supply our products to selected Gas Safe registered installers. You cannot buy our products from ATAG or from merchants. To find a local ATAG Selected installer, please use our ‘Find an ATAG Selected Partner’ tool here.

Q: How much is an ATAG boiler?

Every home and its needs are different. Our ATAG Selected Partners will help you decide which ATAG system will be most efficient for you and then provide a competitive, tailored quote accordingly. To find a local ATAG Selected Partner, please use our ‘Find an ATAG Selected Partner’ tool here.

Technical questions

Q: Where can I download the ONE controller app?
You can download the app for an Apple devices and Android devices via:


Q: My system comes on during the night or in cold weather when not asked for (System has a 7 day digital wireless room stat or 24 hour mechanical wireless room stat)?
Check the minimum room temperature setting; this should be a low temperature setting e.g. 8 °C to 12 °C. If the minimum setting is too high e.g. 18 °C, then when the room temperature falls below 18 °C during an off period, then the wireless room stat will bring on the boiler and keep the house up to 18 °C when the house should be allowed to fall to a much lower temperature whilst no heat is required.

Q: What do I do with the boiler that has a fault code 118?
This means that the system pressure is too low and you may see that the system pressure gauge indicates that the pressure in the system is below the 1 bar pressure.

To re-pressurise the system you will find a filling loop (copper ‘U’ shaped tube with two nuts at each end) on the underside of the boiler or a metal braded flexible hose external of the boiler on the pipework with one or two tap connections at the either end of the filling loop.

The tap or taps should be opened a quarter of a turn and the water will start to refill the system (water should be heard filling the system). You should see the pressure gauge rise back up between 1 bar and 1.7 bar pressure and then stop filling.

Boiler information on water pressure can also be seen on the digital display by pressing the Eco button for 6 seconds and then scroll through to ‘A6’ which will display the water pressure.

Once the pressure gauge is between 1 bar and 1.7 bar turn the taps back to the off position and the water will stop filling the system. The error code 118 will stop and the boiler will now operate. If the error code 118 is still active, fill up the system a little more but not over 2.0 bar.

(If you do fill the system too much and the pressure gauge is too high, just bleed water from a radiator until the pressure on the gauge goes down to below 1.7 bar).

How do I activate my warranty or make a claim?

Q: How do I register my warranty?
Click here to register your warranty.

Q: I have a question regarding my new boiler, who do I contact?
You can contact us on 0800 254 5065 (Mon-Fri 08.30-17.30) or you can contact the ATAG Selected installer who installed your boiler directly.

Which boiler is right for me?

Q: How do I find out which ATAG boiler is right for my home?
You can use our simple tool here to find the perfect ATAG heating solution for your home. Also, you can locate an ATAG selected installer in your local area here. They will able to provide you more information and a quote.


General information on heating systems

Q: What heating system do I have in my home?
Click here to find all you need to know about which heating system you currently have in your home.

Q: How can I achieve A+ ErP rating and make savings on my fuel bills?
ATAG can offer an A+ rating for you when you pair a boiler through our Economiser range with our ONE controller. This combination allows you to have super-efficient heating solution where you could save a further 12% on your gas bills. The ONE controller gives you the complete control on your heating needs, even when you are outside the home through our ONE controller app for Apple and Android devices.

Q: What is the ErP Directive?
ErP stands for ‘Energy related Products’ and is a mandatory piece of legislation created to help achieve targets set for energy consumption, with the goal being to reduce consumption by 20% and increase the share of renewable energies by 20% by 2020.

Q: Who is responsible for ErP?
The regulation is set up by the European Union.

Q: What is the ErP designed to do?
The new directive is designed to help inform homeowners about the efficiency of the heating and hot water products they are buying by displaying a simple energy label that categorises the product according to its efficiency.

Q: How will the ErP compliance be enforced and regulated?
The National Measurements & Office (NMO) will be responsible for ensuring compliance. The ErP requirements are also likely to be included in Part L of the Building Regulations.

Q: Which products are affected?
Space and water heating products will be required to have an energy label, already familiar on other white goods, such as A+++ rated dishwashers and washing machines. Low-rated water heating products (such as those which might have been rated in bands F or G) will not be permitted after the 26th September 2016.

Q: Can a merchant sell unlabelled heating products after 26th September 2016 if they bought the products before that date?
It is not an offence for a merchant to sell a product without an ErP label after the 26th September 2016, as long as that item was in stock prior to that date.

Q: How will it affect installer businesses?
Installers will be responsible for providing the energy labelling for a complete heating system eg if a heating engineer installs an ATAG iC28 combination boiler alongside the ONE controller, the installer will have to calculate the overall system efficiency – which in this case would be 98% or A+ rated.  To calculate the overall efficiency of the heating system, you must record each product on a document known as a product fiche.

Q: What is a product fiche?
A product fiche is a table of technical information that a manufacturer, such as ATAG Heating Technology, is required to provide for each individual product.

Q: How is ATAG helping installers with the new ErP Directive?
ATAG is on hand to help their network of installers with any questions relating to the ErP Directive. This includes setting up a helpline, on 0800 254 5065 and an ErP calculator, which is available from the approved ATAG installer portal.bout d

Help with boiler codes and symbols

  • Setting of hot water temperature
    +/- function (iC Range only)
    (ancillary function: Scroll and +/- function)

  • Setting of boiler temperature
    (max flow temperature) +/- function
    (ancillary function: OK and escape)

  • Eco-function DHW on/off. (iC Range only)
    Press for 6 seconds for boiler information

    Reset Button

  • Commissioning function (Do not use. For service purposes only)

    Pump function (Press both – buttons for 6 seconds) (iC & iS-Range only)

  • Visible when DHW program is active
    Flashing when there is a heat demand for DHW (iC Range only)

  • Visible when heating program is active
    Flashing when there is a heat demain for heating

  • Visible when boiler is active for heating or DHW

  • Visible when DHW comfort function is not active

  • Error indication (accompanied with a code)

  • Service-mode or blocking

  • Visible when pump is set to continuously
    Flashing when frost program is active (iC & iS Range only)

Error Codes

Blocking Code with spanner symbol

Error is temporary and will clear itself or will lock the boiler after several attempts (error)

Error Code with bell symbol

Boiler is locked and can only be remedied by a reset and/or intervention by a service technician

10 Outside sensor error 111 Maximun pressure exceeded
20 Flow sensor error 117 Pressure too high (> 3 bar) or pump pressure increase too high (iC & iS Range only)
40 Return sensor error 118 Pressure too low (< 1 bar) or pump pressure increase too low) no pump detection) (iC & iS Range only)
50 DHW sensor error (iC-Range only) 119 Link on X2 position 4 and 5 missing
61 Bus communication error 129 Fan error (fan does not start up)
78 Water pressure out of range 133 No flame after 5 ignition attempts
105 Venting program active when power turned on or interrupted (runs approx. 7 mins) 151 Fan error (speed control is not achieved or is out of range) or control unit defective
110 Safety temperature exceeded 154 Flow temperature increases to fast, return > flow