Baxi Duo-tec

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*.

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  • Seven year parts and labour warranty for added peace of mind
  • Class leading hot water flow rates for increased comfort and convenience
  • User friendly controls with clear, easy to read display
  • A wide range of outputs to suit all heating and hot water requirements
  • Dedicated LPG 28kW model available, so households in off mains gas areas can enjoy the benefits of the Baxi Duo-tec Combi
  • Energy Saving Trust endorsed product
  • Aftersales services provided by Baxi Customer Support
  • Rigorously tested to meet our exceptional quality control and reliability expectations.

*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.

Duo-tec clearance

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.

  • Pre-plumbing jig, complete with pre-formed copper pipe tails, built in filling loop and 1 metre mains cable to save the installer time and money during installation
  • Built in frost thermostat, making it easier to site in garages and lofts
  • Compatible with Multifit flue kits, which provide an industry leading choice of lengths, bends and accessories, allowing for versatile siting
  • Free of charge Baxi product training throughout the UK 
  • Free Gas Safe notification and warranty registration online, saving you time and money on any Baxi boiler you install through the Baxi Works loyalty scheme 
24 Combi 28Combi 33 Combi 40 Combi 28 Combi LPG
Sales code 7219413 7219414 7219415 7219416 7219417
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
Natural gas   Yes Yes Yes Yes N/A
LPG (propane)   N/A N/A N/A N/A 3
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
Nox Class   5
ErP Product information
NOx mg/kWh 20 23  20  23  23 
Sound power level, indoors Lwa dB 50 53  52  50  53 
Space heating efficiency class   A A A
Water heat declared load profile   XL XL  XL  XL  XL 
Water heating efficiency class   A
Electrical supply Volts/Hz 230V/50Hz  230V/50Hz 230V/50Hz  230V/50Hz  230V/50Hz 
Permanent live required Yes Yes Yes  Yes  Yes 
Fitted electrical cable  

1m x 3 core x 075mm2 on all models

Power consumption Watts 85 120  125  125  120 
External fuse rating Amps 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 
Pump overrun   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
Min domestic hot water operating pressure bar 0.15


0.15  0.15  0.15 
Maximum DHW system pressure bar 8 8
Safety discharge pressure bar 3 3
Integral expansion vessel capacity litres 8 10  10 
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
Twin pipe flue system
Diameters mm 80/80  80/80  80/80   80/80   80/80 
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 


Multifit GasSaver

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.

  • Baxi Duo-tec Combi ErP homeowner guide (PDF 0.77MB, 22/01/2016)
  • Baxi Platinum, Duo-tec and Megaflo ErP range guide (PDF 2.73MB, 14/06/2017)
  • Baxi Duo-tec Combi ErP installation and servicing manual (PDF 11.05MB, 24/05/2017)
  • Baxi Duo-tec Combi ErP user guide (PDF 1.60MB, 01/10/2015)
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