The Baxi Duo-tec Combi boiler is a firm favourite with installers and householders because it is straightforward to install and simple to use. It is an Energy Saving Trust endorsed product, so you can be sure it meets the highest standards of energy efficiency.
We are so confident in the reliability of the Baxi Duo-tec Combi that we are offering a 7-year warranty as standard on all Baxi Duo-tec boilers installed before 31st December 2017*.
*Subject to registration before 31st December 2017 and an annual service. Terms and conditions apply.
Please note: warranty and purchasing information on this site applies to the UK only. For information on how to buy these products in the Republic of Ireland, please visit Baxi Potterton Myson.
A: Boiler width = 450mm
B: Boiler height = 780mm
C: Boiler depth = 345mm
D: Side clearance = 5mm
E: Upper clearance = 200mm
F: Lower clearance = 150mm
G: Front clearance = 5mm in operation, 450mm for servicing
View product specification
When clicked this will open the product specification in PDF format.
|24 Combi||28Combi||33 Combi||40 Combi||28 Combi LPG|
|Concealed user controls||Yes||Yes||Yes||Yes||Yes|
|On/off switch with reset||Yes||Yes||Yes||Yes||Yes|
|User adjustable DHW temperature||Yes||Yes||Yes||Yes||Yes|
|User adjustable CH temperature||Yes||Yes||Yes||Yes||Yes|
|LED temp / status / fault diagnosis display||Yes||Yes||Yes||Yes||Yes|
|Gas supply connection||mm||22||22||22||22||22|
|Nominal inlet supply pressure NG||mbar||20||20||20||20||N/A|
|Nominal inlet supply pressure LPG||mbar||N/A||N/A||N/A||N/A||37|
|Maximum gas rate||m3/hr||2.61||3.1||3.6||4.36||2.25 Kg per hr|
|Heat input central heating||kW max gross (QnHs)||22.7||27.4||32.1||36.4||27.4|
|kW min gross (QnHs)||7.8||10||10.8||11.0||10|
|Heat output CH non condensing||kW max (Pn)||20||24||28||32||24|
|kW min (Pn)||6.8||8.7||9.4||9.6||8.7|
|Heat out CH condensing||kW max (Pnc)||21.0||25.9||30.3||34.4||25.9|
|kW min (Pnc)||7.4||9.5||10.2||12.1||9.5|
|Heat input domestic hot water (DHW)||kW max gross (QnwHs)||27.4||32.1||37.7||45.7||32.1|
|Heat output domestic hot water||kW max (Pn)||24||28||33||40||28|
|Maximum domestic hot water flow rate||l/min @ 35oc||9.8||11.5||13.5||16.4||11.5|
|SAP 2009 annual efficiency (PCDB/SEDBUK)||%||89.0||89.0||88.9||88.9||90.6|
|ErP Product information|
|Sound power level, indoors||Lwa dB||50||53||52||50||53|
|Space heating efficiency class||A||A||A||A||A|
|Water heat declared load profile||XL||XL||XL||XL||XL|
|Water heating efficiency class||A||A||A||A||A|
|Permanent live required||Yes||Yes||Yes||Yes||Yes|
|Fitted electrical cable||
1m x 3 core x 075mm2 on all models
|External fuse rating||Amps||3||3||3||3||3|
|Internal fuse rating||Amps||F2L||F2L||F2L||F2L||F2L|
|Ingress protection rating (without electro-mechanical timer fitted)||IPX 5D||IPX 5D||IPX 5D||IPX 5D||IPX 5D|
|24 hour pump exercise||Yes||Yes||Yes||Yes||Yes|
|Integral 'boiler only' frost thermostat||Yes||Yes||Yes||Yes||Yes|
|Mechanical and hydraulic|
|Compartment ventilation requirement||None||None||None||None||None|
|Pre-plumbing / wall mounting jig||Yes||Yes||Yes||Yes||Yes|
|Flow and return pipe size||mm||22||22||22||22||22|
|Condensate discharge pipe size||mm||21.5||21.5||21.5||21.5||21.5|
|Integral automatic bypass||Yes||Yes||Yes||Yes||Yes|
|Min domestic hot water flow rate||l/min||2||2||2||2||2|
|Min domestic hot water operating pressure||bar||0.15||
|Maximum DHW system pressure||bar||8||8||8||8||8|
|Safety discharge pressure||bar||3||3||3||3||3|
|Integral expansion vessel capacity||litres||8||8||10||10||8|
|Max capacity of central heating system||litres||125||125||155||155||125|
|Filling loop included||Yes||Yes||Yes||Yes||Yes|
|CH system inhibitor required||Yes||Yes||Yes||Yes||Yes|
|Concentric Flue System|
|Standard horizontal flue kit length||mm||685||685||685||685||685|
|Max equiv length horizontal / vertical (60/100mm)||m||10||10||10||10||10|
|Max equiv length horizontal / vertical (80/125mm)||m||20||20||20||20||20|
|Equivalent length per 135o bend||m||0.5||0.5||0.5||0.5||0.5|
|Equivalent length per 93o bend||m||1||1||1||1||1|
|Twin pipe flue system|
|Max equiv length horizontal / vertical (parallel pipes)||m||15/15||15/15||15/15||15/15||15/15|
|Equivalent length per 135o bend||m||0.25||0.25||0.25||0.25||0.25|
|Equivalent length per 91.5o bend||m||0.5||0.5||0.5||0.5||0.5|
|Max installation lift weight||kg||40.2||40.2||41.7||42.2||40.2|
|Gross packaged boiler weight||kg||46||46||47.5||48||48|
A Multifit GasSaver can be installed with the boiler and could contribute additional annual gas savings on domestic hot water of up to 37%** - meaning even more savings on your fuel bills and greater benefit for the environment.
**Test conducted by independent scientific test house, TNO. Calculation based on an average household's consumption of 100 litres of hot water per day. Results were based on a comparison of a SEDBUK 2005 (> 90%) rated high efficiency boiler versus a high efficiency boiler and GasSaver.
Read more about the Baxi Duo-tec Combi by taking a look at our product literature, whether looking for instructions on what to do when changing a boiler part, or finding out about the benefits of using a Baxi.
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