400mm Radiators : The Best Guide

400x500 Brushed Gold Spencer

With compact dimensions of just 400mm tall, 400mm radiators offer an efficient and versatile heating solution for small to medium sized spaces. This in-depth guide provides a detailed overview of 400mm radiators including types, configuration options, tips for sizing and placement, maintenance, costs, and more.

Benefits of 400mm Radiators

The 400mm height offers numerous advantages:

  • Space saving – At just 400mm high, the compact size maximizes heat output while taking up minimal floor area. Ideal for heating smaller spaces.
  • Quick warm up time – Due to their smaller thermal mass, 400mm radiators heat up rapidly after turning on the heating system to provide warmth when you need it.
  • Easy to clean – The shorter height allows for easy access for DIY cleaning and dusting which should be done a couple times per month to keep them looking fresh.
  • Versatile applications – With their modest footprint, 400mm radiators can heat bathrooms, kitchens, bedrooms, home offices, apartment living rooms, and many other rooms effectively.
  • Affordable option – The smaller size makes 400mm radiators very economical both to manufacture and purchase, making heating upgrades budget-friendly.
  • Long lifespan – When made from quality materials like steel or aluminum and properly maintained, 400mm radiators typically last 20-30 years.
  • Lower energy bills – Properly sized 400mm models avoid overheating smaller spaces which saves on energy costs. Their smaller thermal mass means they lose heat quickly when turned off.

“I love the instant heat the compact little 400mm radiators provide in my apartment. They were an affordable and stylish solution.” – Emma R.

Vertical Radiator
Vertical Radiator

400mm radiators come in a diverse range of styles:

Vertical Radiators

  • Slim and streamlined with a depth of just 3.5 inches.
  • Available as single or double panel options. Double panel provides increased heat output.
  • Sleek minimalist look suits modern contemporary spaces.

Column Radiators

  • Classic and decorative 2 or 3 column arrangement in a 400mm height.
  • Provides elegant heating solution for traditional rooms.
  • Freestanding or wall mounted installation.

Curved and Decorative Radiators

  • 400mm size available in creative curved shapes and ornate scrollwork.
  • Unique flourishes and finishes become an artistic focal point.
  • Adds stylistic flair for living rooms, bedrooms, and more.

Electric or Hydronic

  • 400mm radiators can be configured for either electric or hot water hydronic heating systems.
  • Electric models contain long lasting oil filled heating elements.
  • Hydronic models connect to a boiler or district heating to receive hot water.

Oval Column Radiators

  • An elliptical arrangement of vertical columns rather than circular.
  • Slim oval footprint saves space while still providing heat.
  • Sophisticated look for modern or traditional decors tastes.

Choosing Finishes

400mm radiators come in a diverse range of durable metallic or painted finishes:

Polished Chrome – Mirror-like shine suits modern contemporary spaces. Easy to keep clean long-term.

Brushed Chrome – A soft brushed texture adds subtle elegance. Resists fingerprints well.

Matte Black – Deep dark colour for a sleek, stylish statement. Doesn’t show dirt or dust as obviously.

Gloss White – Crisp clean white complements any classic or modern decors. More frequent wipe downs needed.

Stainless Steel – Neutral colour with a slight sheen is versatile for any style. Withstands scratches and wear.

Wood Effect – Faux wood grain pattern provides natural warmth. Protective top coat prevents damage.

Custom Paint – Primed 400mm models can be spray painted any colours to perfectly coordinate with your space.

Placement Tips

Consider these best practices when situating 400mm radiators:

  • Mount 400mm models on walls at least 2-3 inches above the floor to allow air circulation.
  • Avoid placing furniture too close to 400mm radiators which can block airflow and heating.
  • Areas like bathrooms, small bedrooms, kitchens, and offices are well-suited for 400mm radiator sizes.
  • In open plan living areas, use multiple 400mm radiators for zone heating focused where needed.
  • North facing and poorly insulated rooms may need a higher heat output 400mm model to compensate.
  • Finish colours like gloss white and polished chrome maximize visibility so 400mm radiators don’t blend into walls.
  • Place decorative 400mm models like curved or column styles as artistic focal points in living spaces.

BTU Output & Sizing

Choosing the right heat output is critical for 400mm radiator effectiveness:

  • Measure room size and account for heat loss factors like windows, doors, insulation, and ceilings.
  • A heat loss calculator can recommend the proper BTU requirements for the space.
  • Undersizing a 400mm radiator will lead to insufficient warming. Oversizing wastes energy.
  • Standard 400mm models range from 500 BTU for small bathrooms up to 2700 BTU for living rooms and bedrooms.
  • Higher heat output models up to 3500 BTU are available for poorly insulated spaces needing extra heating capacity in a 400mm size.
  • Have a heating specialist assess your space and advise on properly sizing 400mm radiators.

Pros and Cons

Compact size saves spaceDon’t heat very large rooms fully
Quick to warm up smaller areasVisible dust and dirt shows on finishes
Affordable cost effective optionNeed occasional repainting to maintain appearance
Easy DIY cleaningCan’t dry large towels fully
Versatile for many space typesMay lose heat faster once turned off

“I love the fast heating and smaller footprint of 400mm radiators. But have to wipe them down frequently to keep the white finish looking clean.” – Sarah B.

“The small 400mm radiators I installed provide plenty of warmth for my apartment bedroom and bathroom.” – Matt D.

Costs and Pricing

Typical 400mm radiator costs:

  • Basic electric – £100 – £250
  • Medium grade electric – £250 – £400
  • High end designer electric – £400 – £600
  • Basic hydronic – £200 – £350
  • High end hydronic – £350 – £500
  • Fully custom – £500+

Professional install pricing averages:

  • Electric install – £100 – £250
  • Hydronic install – £150 – £300

**Total installed costs for a 400mm radiator can range from: **

  • £250 – £500 – basic stock electric model
  • £500 – £800 – mid-range electric with finishes
  • £800 – £1,100 – high end custom electric

Maintaining 400mm Radiators

To keep 400mm radiators performing well:

  • Wipe down the exterior every couple weeks using a soft dry cloth to remove any dust build up.
  • Use touch up paint to fix any scratches or chips that develop over time. Match original finish.
  • Have electric heating elements replaced by a specialist every 10+ years depending on use.
  • Clean inside electric models periodically using a microfiber cloth and compressed air.
  • Flush hydronic radiators and have a plumber service them annually.
  • Avoid using wet cloths, detergents, or abrasives on exteriors which can damage finishes.


Are 400mm radiators energy efficient?

When properly sized for the space, they avoid overheating rooms which saves energy. Their smaller thermal mass doesn’t retain heat as long once turned off.

Can you mount a 400mm radiator horizontally?

No, they are designed for vertical installation to properly direct convection heating. Mounting flat alters performance.

How long should a 400mm radiator last?

With adequate maintenance, steel and aluminium 400mm radiators typically last 20-30 years. Well maintained cast iron models can potentially function over 50 years.

What rooms are 400mm radiators best suited for?

Their compact size makes them ideal for bathrooms, small bedrooms, kitchens, home offices, apartment living spaces, and other areas under 10’ x 12’.


With versatile applications, affordable prices, and sleek compact sizing, 400mm radiators offer an efficient and stylish heating solution for smaller spaces. Their many finishes and heating configurations provide extensive customization options. Follow proper sizing, placement, and maintenance guidelines so 400mm radiators can keep your rooms cosy for years on come.

Take Action Now!

Explore our best-selling radiators in the UK and choose one that fits your budget and requirements. Don’t settle for a subpar heating system and upgrade your home or business with the best selling radiators today. Your comfort, energy bills, and the environment will thank you.

It is crucial to seek guidance from the manufacturer and a certified professional for the installation process to ensure safety and compliance with all technical specifications and requirements. Proper installation is key to the optimal performance and longevity of the product.

Additionally, professional installation may be necessary to maintain the product’s warranty. Therefore, it is highly recommended to consult with experts and not attempt to install the product yourself unless you are qualified to do so.

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