System Boiler
iS System Boiler
i15S i18S i24S i32S i40SEvery ATAG boiler carries a 10 years warranty as standard with options up to 14 years.
With output sizes in 15kW, 18kW, 24kW, 32kW and 40kW, the compact casing of the iS range houses an outstandingly efficient boiler which offers excellent, low maintenance performance and is easy to install.
Furthermore, we have made these easy for homeowners to operate. With the addition of a 3 port valve kit, the iS system boilers can be controlled using either an ATAG ONE – our intelligent, internet connected programmer – or a 7 day two channel plug-in digital programmer. Speak to your PSM for more details.
Key features and benefits

Compact dimensions
h700 x w440 x d366 (mm)

Five models available
15kW, 18kW, 24kW, 32kW, 40kW

Up to 14 years warranty
Including all parts and labour

Completely user friendly
with intuitive controls

Quiet in operation
Due to bottom-up modulation

Frost protection
With built-in frost protection

ErP "A" rated
Achieves ErP ‘A’ rating for heating and hot water

Loved by customers
ATAG is the UK’s highest rated boiler brand on Trustpilot
- A 275 mm (deep) model is available to fit inside kitchen cupboards
- 10 years warranty as standard with options up to 14 years
- ATAG iCon stainless steel heat exchanger – with its unique lifetime replacement guarantee
- Supplied with fixing jig as standard, for rear piping up behind the boiler
- Combined condensate and pressure relief valve outlet pipe means less pipework
- Detailed fault codes on LCD display for quicker, more accurate boiler diagnostics
- Fully compatible with ATAG iSteel cylinder range & the 3 port valve kit
- Fully compatible with solar thermal hot water systems and ATAG iSteel twin coil cylinder range
- Factory fitted ErP-ready pump for low electrical consumption and improved efficiency
- Control the system via smartphone or tablet using the ATAG ONE controller
- Built-in anti-cycling function for improved efficiency
Specifications
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PART NUMBER
BS300158
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY CLASS
A
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY (%)
93
CH OUTPUT KW (50/30°C)
14.7
SEDBUK 2009 (%)
89.8
DIMENSIONS (H X W X D) MM
700X440X355
BOILER LIFT WEIGHT WITH JIG (KG)
39
STANDARD WARRANTY (YEARS)
10
LPG CONVERSION KIT AVAILABLE
YES
NOX CLASS
6
INGRESS PROTECTION (IP)
IPPX4D
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 60/100MM
18
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 80/125MM
50
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PART NUMBER
BS300118
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY CLASS
A
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY (%)
93
CH OUTPUT KW (50/30°C)
17.5
SEDBUK 2009 (%)
89.8
DIMENSIONS (H X W X D) MM
700X440X355
BOILER LIFT WEIGHT WITH JIG (KG)
39
STANDARD WARRANTY (YEARS)
10
LPG CONVERSION KIT AVAILABLE
YES
NOX CLASS
6
INGRESS PROTECTION (IP)
IPPX4D
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 60/100MM
18
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 80/125MM
50
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PART NUMBER
BS300124
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY CLASS
A
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY (%)
94
CH OUTPUT KW (50/30°C)
23.2
SEDBUK 2009 (%)
89.8
DIMENSIONS (H X W X D) MM
700X440X355
BOILER LIFT WEIGHT WITH JIG (KG)
39
STANDARD WARRANTY (YEARS)
10
LPG CONVERSION KIT AVAILABLE
YES
NOX CLASS
6
INGRESS PROTECTION (IP)
IPPX4D
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 60/100MM
18
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 80/125MM
50
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PART NUMBER
BS300132
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY CLASS
A
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY (%)
94
CH OUTPUT KW (50/30°C)
31.2
SEDBUK 2009 (%)
89.8
DIMENSIONS (H X W X D) MM
700X440X355
BOILER LIFT WEIGHT WITH JIG (KG)
42
STANDARD WARRANTY (YEARS)
10
LPG CONVERSION KIT AVAILABLE
YES
NOX CLASS
6
INGRESS PROTECTION (IP)
IPPX4D
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 60/100MM
18
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 80/125MM
45
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PART NUMBER
BS300140
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY CLASS
A
ERP SEASONAL SPACE HEATING ENERGY EFFICIENCY (%)
94
CH OUTPUT KW (50/30°C)
38.8
SEDBUK 2009 (%)
89.8
DIMENSIONS (H X W X D) MM
700X440X355
BOILER LIFT WEIGHT WITH JIG (KG)
42
STANDARD WARRANTY (YEARS)
10
LPG CONVERSION KIT AVAILABLE
YES
NOX CLASS
6
INGRESS PROTECTION (IP)
IPPX4D
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 60/100MM
18
MAXIMUM EQUIVALENT HORIZONTAL/VERTICAL FLUE LENGTH (M) 80/125MM
45
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OneZone
Control the temperature in your home remotely using the ATAG One Zone App, available for FREE on the App Store or Google Play.
View the OneZone
Cylinders
Need replacement cylinders? Check out our range to see which one each boiler requires.
View all cylinders
Chemicals and filters
We have a range of chemicals and filters that can be used with our boilers.
View all filters and chemicalsInterested in becoming a ATAG Selected Partner?
If you're interested in becoming a ATAG Selected Partner, simply click on the button below to submit your form. If you'd like more information about our boilers, why not book a demo below?
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