Thermaflow Electric Combination Boiler

From £2,519.42 - please choose your options from the list below


The Thermaflow Electric Combination Boiler has been designed with the evolving needs of users in mind. It combats issues such as high energy prices and climate change. With an efficiency rating of 99.4%, the Thermaflow Electric Combination Boiler is suitable for both sealed heating systems and underfloor heating systems.

Key Benefits

  • Low running costs through peak avoidance tariffs and a high efficiency rate of 99% plus
  • Safe – no chance of carbon monoxide poisoning or gas escape
  • Responsive. Radiators reach maximum temperature within 3 minutes
  • Hot water at taps within 5-10 seconds
  • Radiators reach maximum temperature within 3 minutes
  • Minimum Installation time involved
  • No flues, storage tanks, or separate hot water storage required
  • Sealed heating system. Radiators can be positioned above the boiler without the need for additional header tanks
  • Eliminates the need for a booster pump on power showers
  • BEAB Approved
  • WRAS Approved
  • WRc-NSF Ltd Building Regulations Approved
  • CE Approved


The stainless steel vessel is guaranteed for 25 years. Ancillary components and expansion vessels are guaranteed for 2 years (subject to correct installation and annual service by an approved and competent installer).


A range of input powers (9Kw and 12Kw) and capacities (210, 250, 330, 450 and 650 litres) is offered. Please check the boiler model number you require carefully (e.g. TH9-210U MRK 2, etc.) and choose your preferred option from the drop down menu above then click ADD TO CART. If you would like to add another boiler to your order you can CONTINUE SHOPPING. You can also change the quantity of boilers required by entering the quantity required in the quantity box and clicking UPDATE.

If you have any questions about which is the best option for your needs, or would like to arrange installation in the London area, please get in touch.

Important information about choosing the right boiler

Unless you are contracting Selectric Heating to survey your property prior to us installing the boiler on your behalf, choosing a boiler that suits your property type, age and size as well as your heating requirements remains your own responsibility.

To help you we have provided the following downloads which we highly recommend you use to assist you in making the right choice:

Boiler Size Chart (opens as PDF)
This shows suitable and recommended boilers for the E10 tariff according to the house volume and age of the property.

Electricity Usage Chart (opens as PDF)
This shows typical costs associated with running various models of Thermaflow electric boiler.

Property Volume Calculator (opens as Microsoft Excel spreadsheet)
This will assist you in calculating the volume of your property for ease of reference with the above charts. Just enter the dimensions of your various rooms and the total volume of your property in cubic metres will appear in the total box at the bottom.

Optional Accessories

When used in conjunction with a wet electric off peak tariff combining periods of full and reduced rate electricity, the Thermaflow Electric Combination Boiler is best used alongside a Thermaflow off peak time controller. This controller allows you to make maximum benefit of the reduced rate electricity available, reducing electricity costs as much as possible. You can add a controller to your order. Click here to find out more.


Delivery is free to UK mainland addresses and normally takes around 4-5 working days. Deliveries are made by courier and must be inspected and signed for by an adult aged over 18 years.

Terms & Conditions

All purchases are made subject to our terms and conditions. In line with the Distance Selling Regulations you have a right to cancel your order within 14 days. In circumstances other than where goods are damaged or defective, if you decide to return your order then you will be required to cover the shipping cost of the return. Boilers or accessories that have undergone installation cannot be returned. We strongly recommend you read our terms and conditions before placing your order. To read our full terms and conditions of sale, please click here.

All prices are inclusive of VAT at the prevailing rate. Selectric Heating Ltd. VAT No: 193619086.

Please be aware that no official documentation, such as installation certificates, warranties, guarantees, etc. will be handed over until payment is received in full.

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