FAQs
Q: What size radiator do I need for my room?
The right size radiator is determined by your room's BTU (British Thermal Unit) requirement - a measure of how much heat the space needs to reach a comfortable temperature. This depends on room dimensions, ceiling height, glazing type, insulation level and how exposed the property is. The quickest way to work this out is with our free BTU calculator, which gives you a recommended output range in both BTU and Watts in seconds. For a more detailed breakdown of sizing by room type, see our Complete Guide to Radiator Sizing for Every Room.
Q: What's the difference between BTU and Watts?
Both are units of heat output - they measure the same thing, just in different scales. BTU (British Thermal Units) is the traditional measure used for hot water (hydronic) radiators, while Watts is the standard unit used for electric radiators. As a rough guide, 1 Watt equals approximately 3.41 BTU. All heat outputs across our range are displayed at Delta T50°C to ensure fair, consistent comparisons between models. Our BTU calculator gives you both figures automatically, so whichever type of radiator you're considering, you'll have the right number to match against.
Q: How do I choose between a horizontal and a vertical radiator?
The short answer is: let your wall space decide. Horizontal radiators are the traditional choice and work well under windows or along standard walls. Vertical radiators are the better option where horizontal wall space is limited - in narrow hallways, kitchens, beside doors, or in rooms where you want a statement piece without sacrificing floor area. Both orientations can achieve the same heat output; the key is always to check the BTU rating rather than assume size equals warmth. For ideas on making both work in a single space, our guide on choosing the right radiator for open plan living is a useful reference.
Q: How many radiators do I need in a room?
One well-sized radiator is sufficient for most rooms. However, in larger spaces, particularly open-plan living areas or rooms with multiple exterior walls - two smaller radiators positioned at opposite ends will distribute heat more evenly than one large unit. If your BTU calculation returns a figure that's difficult to achieve with a single radiator in the space available, dividing the total across two models is a practical solution. Our radiator sizing guide covers this in more detail.
Q: What's the difference between a column radiator and a panel radiator?
A column radiator (sometimes called a sectional radiator) is made up of a series of hollow vertical columns joined together in rows. It heats both by radiation and convection, gives high heat output relative to its footprint, and has a timeless aesthetic that works equally well in period and contemporary homes. A flat panel radiator has a smooth front surface and is generally more compact and affordable, heating primarily by convection. Column radiators offer more design flexibility - they can be made to order in custom heights, widths and column depths — while panel radiators tend to suit more budget-conscious or minimalist installations. For a full comparison, see our designer radiators vs standard panel radiators guide.
Q: What's the difference between electric and hydronic (hot water) radiators?
A hydronic radiator connects to your central heating system and is heated by hot water pumped from your boiler. It's the most common type and the most cost-effective to run as part of a whole-house system. An electric radiator runs independently from a standard plug or hardwired connection, with no pipework required. This makes electric models ideal for rooms without existing pipework, extensions, outbuildings, or as a supplementary heat source. They're also worth considering if you're on a heat pump system, as they can be run independently from the central heating on milder days. For everything you need to know about how electric radiators work, visit our electric radiators guide.
Q: Are aluminium radiators better than steel?
Neither is universally better; they just suit different situations. Aluminium heats up and cools down significantly faster than steel, making it more responsive to thermostat changes and well-suited to rooms you heat intermittently, or to heat pump systems that operate at lower flow temperatures. It also requires less water to run, which reduces demand on your boiler. Steel, by contrast, holds heat longer after the system switches off and offers greater design flexibility, particularly for made-to-order column radiators. Cast iron sits at the other extreme: very slow to heat up but excellent at retaining and radiating warmth steadily over time, making it ideal for high-ceilinged period properties. Our guide to radiator materials covers the full comparison in detail.