- Vertical, column, designer: what is the difference?
- What size vertical radiator do I need? (BTU table)
- Delta T50 vs Delta T60: the figure that catches people out
- Single or double panel?
- Steel or aluminium?
- Anthracite, white or black?
- Fitting, pipe centres and valves
- How much do vertical and column radiators cost?
- Common questions
Vertical, column, designer: what is the difference?
"Designer radiator" is a catch-all for any radiator chosen for its looks as well as its heat, and most of what we sell under that label falls into three shapes.
| Type | What it is | Best for | Typical depth | PlumbXtra price from |
|---|---|---|---|---|
| Vertical radiator | Tall flat or oval tube panel, usually 1600mm to 1800mm high and 300mm to 560mm wide | Narrow walls, between doors, hallways, kitchens, living rooms | 55mm single, 79mm double (Kartell Aspen) | £89.82 |
| Column radiator | Rows of steel tubes in 2 or 3 columns, the look of cast iron at a fraction of the weight | Period homes, bay windows, under sills (horizontal), feature walls (vertical) | 92mm 2 column, 118mm 3 column | £168.99 |
| Horizontal designer | Same flat or oval tube styling as a vertical, but 600mm high and wide | Under windows, long walls, replacing a standard panel without re-piping | 55mm to 79mm | Varies by width |
| Towel radiator | Ladder rails for bathrooms and kitchens | Bathrooms, ensuites, utility rooms | Varies | Varies |
If you want the practical answer: a vertical radiator solves a space problem, a column radiator solves a style problem, and both can put out as much heat as a standard panel radiator if you size them correctly.
What size vertical radiator do I need? (BTU table)
Radiator output is sold in BTU per hour and watts (1 watt is 3.412 BTU). Work out the heat your room needs first, then choose a radiator that meets or slightly exceeds it. A quick method used by Viessmann: measure length x width x height in metres to get the room volume, then multiply by 108 for a double glazed bedroom or 135 for a double glazed living room. Use a higher figure for single glazing, north facing rooms or more than one outside wall.
| Room | Size (m) | Volume | Heat needed | Vertical radiator that covers it |
|---|---|---|---|---|
| Small bedroom or home office | 3 x 3 x 2.4 | 21.6m³ | 2,330 BTU | 1800 x 300mm single (2,392 BTU at Delta T60, about 1,880 at Delta T50) is marginal; go to a 1800 x 420mm single (about 2,970 BTU at Delta T50) |
| Double bedroom | 4 x 3.5 x 2.4 | 33.6m³ | 3,630 BTU | 1800 x 300mm double (4,664 BTU at Delta T60, about 3,670 at Delta T50) |
| Hallway | 5 x 1.5 x 2.4 | 18m³ | 1,940 BTU | 1800 x 300mm single or a 1800 x 245mm 2 column (2,113 BTU at Delta T50) |
| Living room | 4 x 4 x 2.4 | 38.4m³ | 5,180 BTU | 1800 x 420mm double (6,597 BTU at Delta T60, about 5,190 at Delta T50) or a 1800 x 425mm 3 column (5,176 BTU at Delta T50) |
| Large living or open plan kitchen | 6 x 4 x 2.4 | 57.6m³ | 7,780 BTU | 1800 x 540mm double (8,397 BTU at Delta T60, about 6,610 at Delta T50) plus a second radiator, or two 1800 x 420mm doubles |
Enter the room and we will give you the output to look for, at Delta T50 and as the Delta T60 figure shown on Kartell Aspen listings.
Method: room volume x 108 (bedroom) or 135 (living room) BTU per cubic metre for double glazing, as published by Viessmann UK, with uplifts for single glazing and exposed walls. Delta T60 equivalent is Delta T50 divided by 0.787. This is a sizing estimate; your installer should confirm with a heat loss calculation.
Two things to remember. First, you can split the output across two radiators, and in a long room that heats more evenly than one big one. Second, if a room is too big for one vertical radiator, a horizontal double or a 3 column radiator on a longer wall often gives more BTU for the money.
Delta T50 vs Delta T60: the figure that catches people out
Delta T is the difference between the average water temperature in the radiator and the room. The UK and European test standard, BS EN 442, rates radiators at Delta T50 (roughly 75°C flow, 65°C return, 20°C room), which is what a modern condensing boiler runs at. Some manufacturers and retailers quote Delta T60 instead, which makes the same radiator look about 27% more powerful.
- To convert a Delta T60 figure to Delta T50, multiply by 0.787.
- To convert Delta T50 to Delta T60, multiply by 1.27.
- On a heat pump running at Delta T30 to T35, expect roughly half the Delta T50 output. Eastbrook, for example, lists its Addington aluminium vertical at 3,100 BTU at Delta T50 and 1,542 BTU at Delta T30.
Single or double panel?
A single panel vertical has one row of tubes; a double has two rows back to back. On the Kartell Aspen range a double gives about 75% more heat than the same size single (1800 x 300mm: 2,697 BTU single against 4,664 BTU double; 1800 x 420mm: 3,777 against 6,597) for an extra 24mm of depth and £10 to £45 more.
| Single panel | Double panel | |
|---|---|---|
| Depth (Kartell Aspen) | 55mm | 79mm |
| Output, 1800 x 420mm, Delta T60 | 3,777 BTU | 6,597 BTU |
| Output, 1800 x 420mm, Delta T50 | about 2,970 BTU | about 5,190 BTU |
| Empty weight, 1800 x 420mm | Lighter | 26.4kg |
| Choose for | Bedrooms, hallways, offices, new builds, second radiator in a room | Living rooms, kitchens, older homes, rooms with large windows or two outside walls |
| PlumbXtra price from | £89.82 | £114.00 |
If the maths says a single is marginal, buy the double. A slightly oversized radiator just reaches temperature sooner and the thermostatic valve closes it down; an undersized one runs flat out and the room never gets there.
Steel or aluminium?
Almost every vertical and column radiator is mild steel: the Kartell Aspen and Boston, Scudo Apex, Senator Nirvana, Milan and Venus, and our 2 and 3 column verticals are all steel. Steel is cheaper, holds heat for longer after the boiler stops, and is easy to get in any colour.
Aluminium radiators such as the Eastbrook Addington and Kartell Allegro heat up faster, weigh around 40% less (the Addington 1800 x 366mm is 16.07kg against 26.4kg for a steel Aspen double of similar width) and hold less water, which suits heat pumps and low temperature systems. The trade off is price: aluminium verticals on PlumbXtra start at £321, around double a steel equivalent, and output per metre of width is not higher, so you still need to size them properly.
Anthracite, white or black?
White is the cheapest and matches skirting and window frames. Anthracite (Kartell calls it textured grey) is the most searched designer finish in the UK and typically adds £5 to £8 on an Aspen vertical. Black suits dark kitchens and industrial schemes, and on our column radiators black is the same price as white. Chrome and brass finishes are mostly towel radiators and generally give less heat than the same radiator in painted steel, so check the BTU on the product page rather than assuming.
Browse by colour: anthracite verticals, white verticals, black verticals.
Fitting, pipe centres and valves
- Pipe centres. Vertical and column radiators connect at the bottom, one valve at each end. On the Kartell Aspen and our column range the pipe centres equal the radiator width (a 420mm Aspen has 420mm centres), so if you are replacing a standard panel radiator the pipework will almost always need moving.
- Wall fixings. A double vertical weighs 20 to 40kg empty and more when full. Fix into brick or block, or into timber studs behind plasterboard, never into plasterboard alone. Brackets and fixings are included with the Aspen and column ranges.
- Valves are sold separately. You need a pair: a thermostatic radiator valve (TRV) on one side and a lockshield on the other. Straight valves suit pipes coming up from the floor; angled valves suit pipes from the wall. Match the finish to the radiator from our radiator valves range.
- Projection. Total wall-to-face distance is 79mm for a double Aspen, 92mm for a 2 column and 118mm for a 3 column. Check the 3 column clears door swings and furniture.
- Who fits it. Swapping like for like is a plumber's job of 1 to 2 hours; moving pipework adds time. Radiators are delivered only; we do not fit.
How much do vertical and column radiators cost?
Prices below are PlumbXtra prices including VAT at the time of review. Delivery is calculated at checkout and varies by item and supplier.
| Radiator | Output as listed | Guarantee | Price |
|---|---|---|---|
| Kartell K-Rad Aspen 1800 x 300mm single, textured grey | 2,392 BTU (Delta T60) | 5 years | £89.82 |
| Premium Aspen 1800 x 300mm single, white | 2,697 BTU (Delta T60) | 5 years | £111.60 |
| Kartell K-Rad Aspen 1800 x 300mm double, white | 4,664 BTU (Delta T60) | 5 years | £114.00 |
| Kartell K-Rad Aspen 1800 x 420mm double, white | 6,597 BTU (Delta T60) | 5 years | £159.36 |
| 2 column vertical 1800mm, white or black | 2,113 to 5,074 BTU (Delta T50) | 5 years | from £168.99 |
| 3 column vertical 1800mm, white or black | 2,875 to 5,176 BTU (Delta T50) | 5 years | from £194.00 |
| Kartell K-Rad Aspen 1800 x 540mm double, white | 8,397 BTU (Delta T60) | 5 years | £207.66 |
| Senator Nirvana 1800 x 360mm double, white, anthracite or black | See product page | See product page | £217.80 |
| Senator Vintage 2 column 1800 x 372mm, white, anthracite or black | 4,982 BTU as listed | 20 years | £238.85 |
| Kartell Allegro aluminium 1775mm double, white | See product page | 5 years | from £321.13 |
| Eastbrook Addington aluminium 1800 x 366mm, white | 3,100 BTU (Delta T50) | 5 years | £433.00 |
As a rule, a steel vertical costs £90 to £210, a column vertical £170 to £315, and an aluminium vertical £320 to £435. Add £14 to £30 for a pair of valves.
Three we recommend most often
Kartell K-Rad Aspen 1800 x 420mm Double White6,597 BTU at Delta T60 (about 5,190 at Delta T50). 79mm deep, 420mm pipe centres, fixings included. Our best seller for living rooms and hallways.£159.36View radiator
2 Column Vertical Radiator, White or Black1500mm and 1800mm high, 245mm to 560mm wide. Up to 5,074 BTU at Delta T50. 92mm deep. Every size shows BTU and pipe centres before you buy.from £168.99View radiator
Kartell K-Rad Aspen 1800 x 300mm Single Textured Grey2,392 BTU at Delta T60 (about 1,880 at Delta T50). Just 55mm deep and 300mm wide. The anthracite look for hallways, cloakrooms and small bedrooms.£89.82View radiatorCommon questions
Are vertical radiators as efficient as horizontal ones?
Yes. Output depends on surface area, panel type and water temperature, not orientation. A vertical and a horizontal radiator with the same BTU rating heat a room equally well. The difference is where the heat enters the room: a horizontal under a window counters the cold draught from the glass, while a vertical on a side wall does not, so in a room with a large single glazed window a horizontal is the better position.
Do vertical radiators need special valves?
No, they use the same 15mm valves as any other radiator. Because the connections are at the bottom and the pipe centres equal the width, you normally need a pair of angled or straight valves and new tails. Valves are not included with the radiator.
Can I use a vertical or column radiator with a heat pump?
Yes, but size it for the lower flow temperature. At Delta T30 to T35 a radiator gives roughly half its Delta T50 output, so a room that needs 5,000 BTU would need a radiator rated around 10,000 BTU at Delta T50, or two radiators. Aluminium models and 3 column radiators give the most output per wall width for heat pump systems.
What is the difference between a 2 column and a 3 column radiator?
Depth and heat. At 1800 x 425mm our 2 column vertical gives 3,806 BTU and stands 92mm off the wall; the 3 column gives 5,176 BTU and stands 118mm off the wall. Choose the 3 column where you need the output in a narrow width, and the 2 column where projection matters.
What does Type 20, 21 or 22 mean on a vertical radiator?
The first digit is the number of panels and the second is the number of convector fin sets. Type 20 is two panels with no fins (the Eastbrook Addington), Type 21 is two panels with one fin set, Type 22 is two panels with two fin sets and gives the highest output for its size. Oval tube designer verticals such as the Aspen are simply described as single or double rather than by type number.
How long does a vertical radiator take to heat up?
A steel double holds more water than a single so it takes a few minutes longer to reach temperature, and an aluminium radiator is quicker than either. In normal use with a thermostatic valve the difference is not noticeable.
What guarantee do designer radiators come with?
Kartell K-Rad, Eastbrook and our own 2 and 3 column verticals carry a 5 year manufacturer guarantee. Senator Vintage column radiators carry a 20 year guarantee. The guarantee covers manufacturing defects and assumes the system is correctly inhibited and the radiator is installed by a competent person.
Not sure which size to order?
Call our heating team on 01282 429061, Monday to Friday 7:30am to 5pm and Saturday 8am to 2pm. Tell us the room size, glazing and the wall space you have, and we will tell you which radiator fits and convert the Delta T figures for you.
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