Buying guide
Vertical vs Horizontal Radiator
Choose the orientation that meets the calculated heat output and fits the usable wall. Horizontal radiators offer broad availability and often suit space beneath windows.
Vertical radiators can use a narrow wall and free space for furniture, but height does not guarantee higher output.
Work out the radiator output I need first
| Factor | Horizontal radiator | Vertical radiator |
|---|---|---|
| Wall shape | Uses more width and less height | Uses less width and more height |
| Common location | Beneath windows or along external walls | Narrow piers, kitchens and furniture-constrained rooms |
| Product choice | Broad range of standard panel types | More model-specific sizes, finishes and connections |
| Output | Determined by exact size, type and Delta T | Determined by exact size, type and Delta T |
| Installation | Familiar connections still require correct brackets and pipework | Weight, wall fixing, connection position and clearances need careful checking |
Output comes first
A tall narrow panel can have less surface area or a different convector arrangement than a wide Type 22. Compare the published watts at the intended system temperatures.
Purmo's vertical technical catalogue shows that outputs vary by vertical type, width, height and temperature.
Room layout
A horizontal radiator beneath glazing can use otherwise awkward wall space, but full-length curtains and furniture may obstruct it.
A vertical radiator can release a longer wall for a sofa or cabinets, yet its height may conflict with shelves, switches or sloping ceilings. Include valve projection and access for bleeding and maintenance.
Appearance and availability
Colour and form matter in a visible room, but unusual finishes, sizes and connections can reduce choice or increase cost. Confirm lead time, brackets, valves and exact pipe centres before altering plumbing.
Never assume a product photograph establishes its type or heat output.
Installation and system fit
Radiators are heavy when filled and need suitable fixings for the wall construction. Pipe sizing, flow, balancing and control remain part of the heating design.
Replacing a horizontal radiator with a vertical one of equal headline BTU at a different Delta T can still produce the wrong result.
Start with what size radiator do I need? and the radiator calculator.
Then compare Type 21 vs Type 22 and Delta T before asking a competent installer to confirm the selection.
Compare layouts on paper first
Draw both options to scale on a simple wall elevation. Include the complete radiator, brackets, valves, pipe centres, skirting, sockets, switches, shelves, curtains and door swing. Mark the manufacturer's required clearance above, below and to the sides.
This exposes conflicts that a product photograph hides.
A vertical radiator can be useful beside patio doors or in a kitchen where low wall space is occupied by cabinets. A horizontal radiator can make use of a wide area below a window.
Neither position is automatically thermally superior; construction, glazing, furniture and airflow shape the result.
Shortlist checklist
- Required watts at the design Delta T are met by the exact model.
- The filled weight can be supported by suitable wall fixings.
- Flow and return connections match the proposed pipe layout.
- Valves remain accessible and do not create an obstruction.
- Air can circulate without a close shelf, sofa or curtain.
- Bleeding, cleaning and future removal remain practical.
- Finish, lead time and replacement availability are acceptable.
Be careful when comparing a decorative vertical model with a standard horizontal panel. Differences in panel construction, convectors and surface area can matter more than orientation.
Use the manufacturer's technical sheet for both and put their corrected outputs at the same temperature condition side by side.
Changing orientation may require pipe alterations and new wall penetrations, so include installation work in the comparison.
A competent installer should confirm the fixing method, pipework and whole-system compatibility before the room is redecorated around the proposed radiator.
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