ATAG

Warranty

Warranty
Contact Us

Contact Us

Privacy policy

Cookie policy

Complaints

Terms & conditions

Products

Find your perfect boiler

Find your perfect boiler
iC Economiser combination

iC Economiser combination
iC Combination

iC Combination
iS System

iS System
iR Regular

iR Regular
Smart controls & thermostats

Smart controls & thermostats
Cylinders

Cylinders
Heat pumps

Heat pumps
Coming 2026

Electric boilers

Electric boilers
Coming 2026

Support & Advice

Support Hub

Support Hub
Product manuals

Product manuals
Troubleshooting

Troubleshooting
ATAG Zone app

ATAG Zone app
ATAG ONE Zone

ATAG ONE Zone
ATAG Cube

ATAG Cube
ATAG Roomstat

ATAG Roomstat
TADO v3

TADO v3
FAQs

FAQs
Winter boiler care

Winter boiler care
Radiators

Radiators
System Boiler Image

iS SYSTEM

Sealed system boiler

Perfect for busy family homes with multiple bathrooms, the iS System boiler range works in harmony with our iSteel cylinder range to deliver a high volume of hot water and ensures powerful pressure and consistent temperatures throughout the day.

[1] With ATAG ONE Zone an A+ 98% heat rating can be achieved. An A 94% rating as standard.
Key Features
ErP 'A' rated saving you money on your gas bills
Five models available: 15, 18, 24, 32, and 40kW
Pair with one of our iSteel cylinders
ErP 'A' rated saving you money on your gas bills
Lifetime iCon Heat Exchanger replacement guarantee
Five models available: 15, 18, 24, 32, and 40kW
Pair with one of our iSteel cylinders
ErP 'A' rating icon ErP 'A' rating
Achieves ErP 'A' rating for all models.
Quiet in operation icon Quiet in operation
Due to bottom-up modulation.
Built-in expansion vessel icon Built-in expansion vessel
Saving space and energy.
Compatible icon Compatible
With our range of smart and thermostat controls.
Download product sheet
Boiler Finder
  • 1

    Tell us about your home

  • 2

    Our product suggestion

  • 3

    Get your free quote

Why are you looking for a new boiler?

hammer (1)

Broken

down (1)

Failing

maintenance (2)

Refurbish

up (1)

More efficient

What type of house do you have?

finder-flat-img

Flat

finder-tarraced-property

Terraced

finder-semi-house

Semi-detached

finder-detached-house

Detached

How many bedrooms does it have?

  1 2 3 4+
Next

How many bathrooms/ensuites does it have?

  1 2 3 4+
Next

Do you know what type of boiler you already have?

question

Don't know

combi-diagram

Combi

system-diagram

System

regular-diagram

Regular

Back
Cylinders

ATAG iSteel cylinder range

for iS System and iR Regular boilers

Find out more

Controls & thermostats

A great choice in control for your heating and hot water

image of a man using an ATAG Room Stat
ATAG OneZone

ONE Zone

Effortless smart heating control for ultimate comfort and reduced home energy bills.

Find out more

ATAG Cube

Cube controller

Straightforward, programmable digital thermostat for simple, reliable, and fuss-free heating control.

Find out more

ATAG Room Stat

Programmable room stat

Classic, user-friendly design with flexible seven-day scheduling for reliable home comfort.

Find out more

Downloads