The smarter way to replace your boiler

  • Get FREE Quotes today
  • Compare quotes & save money
  • Over 5,000 engineers across the UK
Tell us about your job
Get Free Quotes

Potterton Promax Ultra Combi

The Potterton Promax Ultra Combi is a condensing natural gas and LPG ready boiler that is designed to suit homes of all sizes.

Potterton has developed the Promax Ultra Combi for small, medium and large homes that are either on or off the gas grid because it suits both natural gas and LPG without the need for a special conversion kit. It comes in outputs from 24kW to 40kW, with the highest option being ideal for larger properties with greater demands. As this boiler doesn’t require a cylinder or any loft tanks, it’s also perfect for homes that lack space.

How Much Does this Boiler Cost?

The cost will mostly depend on whether you need the 24kW, 28kW, 33kW or 40kW output model. Potterton Promax Ultra Combi prices vary according to these outputs, typically between £960 and £1,310 including VAT. You mustn’t forget to factor in the fitting cost as well. It’s usually best to shop around and compare prices from different suppliers and installers to find deals and cut costs.

How will I know if this Boiler is Suitable for My Home?

This is a combi boiler (or combination boiler), which means it takes water directly from the mains and heats the water instantly. Because it has the ability to do this, the Promax Ultra Combi doesn’t need to be installed with a separate hot water storage cylinder or cold water tank and is, therefore, a fantastic option for homes that lack the space for these components. Also, the boiler is available in low and high heat outputs, making it suitable for small, medium and large-sized properties.

Combi boilers, such as this one, are the most popular type of boiler in the UK, but you’ll still need to check if a combi is the right type of boiler for your home. We recommend you ask a Gas Safe registered engineer to assess your property and unique requirements so that they can help you determine the correct boiler type and heat output.

Is it a High Efficiency Boiler?

The Potterton Promax Ultra Combi has a SAP seasonal efficiency figure of 89.1%, so it’s actually an A-rated boiler that can help you to save some money on those fuel bills. If you don’t mind paying a bit extra, you can improve boiler efficiency by opting for some optional controls or accessories. Compatible controls include programmable wireless sensors, as well as the impressive Multifit GasSaver heat recovery system for lower energy bills and greater carbon savings. You should also know that this boiler is an Energy Saving Trust endorsed product, meaning it meets strict energy efficiency criteria.

Does this Boiler have a Good Range of Controls and Features?

Potterton’s Promax Ultra Combi has an off/off switch with reset, an LED display that lets you see the boiler status, temperature and fault diagnoses and adjustable central heating and hot water temperature controls, all of which are concealed behind a drop-down panel. Key features include built-in frost protection, flue length options up to 20 metres to offer flexibility of siting and front access to components to save your engineer time during servicing. The boiler also comes with a special indicator that reminds you when your annual service is due. To enhance comfort levels and system control, you can buy an optional outdoor weather sensor.

How long is the Warranty on this Boiler?

If you go on to purchase the Promax Ultra Combi, you’ll receive a 2-year parts and labour warranty as standard, as long as you register the boiler with Potterton within 30 days of installation and get it serviced annually.

Potterton Promax Ultra Combi Sizes and Prices


ModelTypeDimensionsMaximum Flow RateOutputEfficiency RatingTypical Price
Promax Ultra Combi 24CombiH – 763 mm
W – 450 mm
D – 355 mm
9.8 l/min24 kWA 90% and above£960
Promax Ultra Combi 28CombiH – 763 mm
W – 450 mm
D – 355 mm
11.5 l/min28 kWA 90% and above£1110
Promax Ultra Combi 33CombiH – 763 mm
W – 450 mm
D – 355 mm
13.5 l/min33 kWA 90% and above£1220
Promax Ultra Combi 40CombiH – 763 mm
W – 450 mm
D – 355 mm
16.4 l/min40 kWA 90% and above£1310

Summary of Important Information

  • Priced between £960 and £1,310
  • Heating output of 24kW, 28kW, 33kW or 40kW
  • Hot water flow rates of 9.8, 11.5, 13.5 or 16.4 litres per minute
  • Dimensions of 763mm (H) x 450mm (W) x 355 (D)
  • Uses gas or LPG as its fuel source
  • A-rated for efficiency
  • 2-year warranty as standard

Pros and Cons

A Which? survey revealed that engineers are more keen on Potterton boilers than customers, so it might be wise to take a look at some user reviews prior to purchasing this boiler. Below, you can find all the pros and cons of the Promax Ultra Combi.

  • Suited to small, medium and large-sized homes
  • Natural gas and LPG ready – no need for a conversion kit if you live off the gas grid
  • No need for separate cylinder or loft tanks
  • Flue length options up to 20m – siting flexibility
  • Concealed controls – ideal for families with young kids
  • Annual service indicator – reminds you when your annual boiler service is due
  • Front access to all components – easy to repair and service
  • Built-in frost protection – can be installed in a garage or basement
  • Provides maximum energy efficiency – reduce fuel bills and carbon emissions
  • Compatible with outdoor weather sensor – enhances comfort levels and system control
  • Compatible with Baxi Multifit GasSaver heat recovery system – proven to achieve savings of up to 7% and can reduce the gas used to heat water by up to 37% annually


  • Potterton boilers have an overall Which? score of 54%
  • 2-year warranty – would prefer a longer standard guarantee
Get Potterson Boiler Quotes

Get quotes to supply a new Potterson boiler now