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Potterton Promax System

The Potterton Promax System is a fully modulating boiler that can stand up to high heating and hot water demands.

Available in five heat outputs, the Promax System is an A-rated boiler that is suitable for properties of most sizes. It’s also a fully modulating appliance and can intelligently adjust its output to ensure the correct amount of fuel is being used to match demand. The boiler requires a hot water storage cylinder but doesn’t need to be installed with a cold water tank, making it a fantastic option for homes with limited loft space.

How Much Does this Boiler Cost?

The Potterton Promax System can be purchased in a model of 12kW, 15kW, 18kW, 24kW or 32kW, which means there are options available to suit most small, medium and large homes. Prices vary according to these heat outputs and start at around £810 and go up to £980 including VAT. It’s important to remember that these figures do not include the fitting cost, so you’ll need to shop around to find the best price on the boiler and installation.

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

Like all system boilers, the Promax System must be installed together with a cylinder for storing hot water (usually found in an airing cupboard). System boilers tend to be most suited to homes with more than one bathroom or high hot water demands because they can provide a constant supply of hot water to multiple taps, showers and baths. Not only that but system boilers are great for properties that don’t have much or any roof space as they don’t require loft tanks.

We recommend you consult a Gas Safe registered engineer prior to purchasing the Potterton Promax System (or any other boiler) so that your home and needs can be assessed. Once an assessment has been carried out, your engineer will be able to tell you the correct boiler type and heat output for your property.

Is it a High Efficiency Boiler?

This is an A-rated and Energy Saving Trust endorsed boiler that has a seasonal space heating energy efficiency of 92%, meaning it could potentially save you a chunk of cash on your annual fuel bills. As it’s fully modulating, the Promax System will automatically adjust its heat output when it senses that less is heat is required so that you don’t waste any energy. If you want to reduce running costs further and ensure maximum heat efficiency, you can use the boiler with a Megaflo Eco Solar Cylinder or Santon Premier Plus Solar Cylinder.

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

The boiler comes with a range of concealed controls, such as an on/off switch, system pressure gauge, an adjustable central heating temperature control and an LED operating display that lets you see the boiler status. It’s a condensing boiler that has robust hydraulic connections to improve reliability, a pre-plumbing jig to save time on installation and flue length options up to 20 metres to allow for greater siting flexibility. In addition to being compatible with solar cylinders, the Potterton Promax System can also be installed with a Multifit GasSaver heat recovery system that recycles the heat from flue gases that would otherwise be wasted.

How long is the Warranty on this Boiler?

Potterton’s Promax System is backed by a 2-year parts and labour warranty as standard. You’ll need to make sure you register the boiler within 30 days of installation and get it serviced every year in order to keep this warranty valid.

Potterton Promax System Boiler Sizes and Prices

Summary of Important Information

  • Priced between £810 and £980
  • Heating output of 12kW, 15kW, 18kW, 24kW or 32kW
  • Dimensions of 450mm (H) x 780mm (W) x 345mm (D)
  • Uses gas as its fuel source
  • A-rated for efficiency
  • Solar compatible
  • 2-year warranty as standard

Pros and Cons

Potterton boilers don’t have the best Which? score but the Promax System is affordably priced and very energy efficient to offer you savings year after year. For a full list of the pros and cons, see below.

  • Suited to small, medium and large-sized homes
  • Fully modulating – intelligently uses the right amount of fuel
  • Flue length options up to 20m – siting flexibility
  • Easy to use and service
  • NOx Class 5 boiler – kinder to the environment
  • Pre-plumbing jig – makes installation easier and quicker
  • Provides maximum energy efficiency – reduce fuel bills and carbon emissions
  • Compatible with Megaflo Eco Cylinders and Santon Premier Plus Solar Cylinders – increases energy efficiency and improves comfort levels and hot water performance
  • 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%
  • Requires separate cylinder
  • 2-year warranty – would prefer a longer standard guarantee
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