A split can take the edge off an orangery in winter by heating the air. It will not feel like radiators or underfloor heating, because it does not warm the slab or the glass. Glass loses heat quickly, warm air from a high unit sits at the ceiling, and feet stay cold. Survey the glass and ask for heating capacity at a low outdoor temperature. Use it as air heating with that limit understood. F-gas rules apply. In England, site the outdoor unit under the Planning Portal conditions.
Glass loss on a cold night
Orangeries are mostly glazing and a roof lantern. Heat leaves through that glass far faster than through an insulated wall. A split sized only on a summer cooling guess can be too small on a cold night, or large enough in name and still unable to make the seating feel warm because the surfaces stay cold. Expect large glass losses. Ask for heating capacity at a stated outdoor temperature, and for how the unit behaves in defrost. A headline cooling kW is the wrong brochure line for January. Ask for heating kW in cold outdoor air.
Warm air in the lantern, cold tiles underfoot
High wall units blow warm air upwards. In a lantern roof that air pools in the roof and the slab, which is often uninsulated, stays cold. People say the unit is on and the room is still miserable. They are feeling radiant cold from the glass and the floor. Radiators and underfloor heating warm those surfaces. A split does not. A split heats air, not the floor slab. It will not feel like radiators.
Summer glass, defrost water and the extension boundary
The same glass is a large cooling load on a sunny day. A unit chosen only for a mild winter evening may be reasonable for cooling or reasonable for heating and not both, until somebody does both sums. Shading and the roof fabric change the summer figure. Condensate in heating mode leaves at the outdoor unit and must not ice a path. Use an F-gas certified company. Read the Planning Portal conditions in England for the outdoor position, which on an orangery is often a boundary wall of an extension. Energy Saving Trust's air-to-air notes describe this kind of heating with the limits of heating air.
Frequently asked questions
Will a split heat an orangery like the radiators in the house?
No. It heats the air. The glass and the slab stay comparatively cold, so the room will not feel like radiant heating. It can take the edge off if the capacity is honest.
Is a floor console better in winter?
It puts warm air lower, which helps the seats. It still does not warm the slab. Treat it as better air distribution, not as underfloor heating. A floor console is still air.
The summer unit is already sized. Will it be fine in January?
Only if the heating capacity at low outdoor temperature covers the glass loss. Ask for that figure. Cooling kW does not answer it.
Does the split warm the orangery slab?
No. A split heats air, not the floor slab. Feet stay cold on an uninsulated floor even when the unit is on. Say if that compromise is acceptable, or if the orangery needs a real heat source and the split is only for summer.
Where does the water go when the unit is heating?
Condensate in heating mode leaves at the outdoor unit and must not ice a path. Shading and the roof fabric change the summer cooling figure. They do not turn winter air heating into radiators.
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How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.