Propane greenhouse heater: what size to buy
Updated: 22 October 2026
You are choosing a first propane greenhouse heater for a UK glasshouse or an allotment house, and the search results mix a 2 kW frost heater with a 15 kW workshop blower. Those are different tools. This page is the fork: the size of the house, the winter fuel, and whether a socket exists at all. It does not pick a winner among the three blowers in the [gas greenhouse heater comparison](/hub/heating/gas-greenhouse-heater). Peter F. used amazon.co.uk listings from 20 October 2026 and public UK sources, not a lab. A qualifying purchase can earn a commission at no extra cost to you.
You are choosing a first propane greenhouse heater for a UK glasshouse or an allotment house, and the search results mix a 2 kW frost heater with a 15 kW workshop blower. Those are different tools.
You are choosing a first propane greenhouse heater for a UK glasshouse or an allotment house, and the search results mix a 2 kW frost heater with a 15 kW workshop blower. Those are different tools. This page is the fork: the size of the house, the winter fuel, and whether a socket exists at all. It does not pick a winner among the three blowers in the gas greenhouse heater comparison. Peter F. used amazon.co.uk listings from 20 October 2026 and public UK sources, not a lab. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Output | Fuel | Fan | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Bimson Power Bimson Power 15 kW | 7–15 kW | Propane; butane named | 13 A plug | 9.4 | about £119.99 | View offer |
 DAHTEC DAHTEC 10 kW | 10 kW | Propane | 18 V battery | 9.4 | about £219.00 | View offer | |
 Bimson Power Bimson Power 30 kW | 12–30 kW | Propane; butane named | 13 A plug claimed | 0.0 | about £169.99 | View offer |
On this page
Two different propane heaters
A purpose-built propane greenhouse heater is what UK garden shops mean by frost heat. Greenhouse Stores, as a retailer, says 2 kW suits many insulated houses up to about 8×10 ft, and 3–4 kW is their rule of thumb above that. They price an Eden 2 kW at £140 and a Regal 4 kW at £279. Those are shop prices, not amazon.co.uk prices, and those heaters are not in this comparison. Calor’s Super Heat page is a 4.2 kW propane model with a thermostat from 7–32 °C, an oxygen depletion device, and a claim of up to 200 sq ft, shelf £129 shown at £107.50. Bio Green Frosty states about 2.5 kW and about 220 g/h, at £269 on that retailer.
The other object is a forced-air blower. The three listings kept here are 10 kW, 7–15 kW and 12–30 kW, sold for garages and workshops, with greenhouse as an extra word. A 15 kW jet in a shut 6×8 ft house is a workshop tool in the wrong room, not a stronger Eden.
Size, propane, and a socket
For a 6×8 ft hobby house, start from that retailer band, not from 15 kW. Treat 2 kW up to about 8×10 ft, and 3–4 kW above it, as Greenhouse Stores’ rule of thumb, not a heat-loss calculation for your glass. A 6×8 ft house does not sit inside a 300 m³ or 700 m³ claim. The DAHTEC page uses 100 m² and 320 m³/h, which is area and airflow, not the same unit.
Winter fuel is propane. Bio Green says the red cylinder for winter and that butane (blue) will freeze. Liquid Gas UK puts low-pressure propane at about 37 mbar and butane at about 28–30 mbar. Match the regulator to the cylinder and the data plate. The Bimson manual prints 300 mbar for the 15 kW and 700 mbar for the 30 kW. That is not a 37 mbar patio regulator.
Both Bimson fans claim a pre-fitted 13 A plug. With no mains, they are not a no-electricity heater. The DAHTEC fan is an 18 V battery, still a propane flame, still limited to outdoors or a well-ventilated non-domestic area. Whether gas beats a proper electric supply is on gas vs electric greenhouse heater.
What this comparison actually contains
The comparison keeps three unflued blowers, not the Eden-class heater above. Prices and star lines are in the table: about £119.99 with 4.7 from 24 ratings, about £169.99 with no star line, and about £219.00 with 4.7 from four ratings. Reviews that exist describe garages, a workshop or a barn, not a crop house. The 30 kW power-source field says propane while the bullets claim a 13 A plug.
A ventilated workshop with a socket is a ranking question for the next page. A 6×8 ft glasshouse is not the heater these garden shops are describing.
What to leave on the shelf
Leave a camping stove. The NHS warning about burning camping fuel in a tent is about people, and a shut glasshouse is still a small closed volume. An extension lead from the house is not a greenhouse supply.
Do not seal every vent so the kilowatts stay in. The Royal Horticultural Society treats gas as the fallback where there is no electric supply, because the flame releases water, ethylene and carbon monoxide. The plant note is H2 or hardier crops. Calor’s Super Heat page asks for at least 50 cm² at the top and the bottom, and says that model is not for polytunnels. That area is that heater’s instruction, not a formula for these blowers. What to leave open is on carbon monoxide greenhouse heater ventilation. A thermostat and an oxygen depletion device are what the 2–4 kW shop heaters advertise. None of the three blower listings names an oxygen depletion device, and that device is still not a carbon monoxide alarm.
Common questions
What size propane heater does a 6×8 ft greenhouse need?
Start around 2 kW for frost protection of hardier plants in a typical small UK glasshouse. Greenhouse Stores keeps 2 kW for many insulated houses up to about 8×10 ft, and 3–4 kW above that. A 6×8 ft house does not need a 15 kW or 30 kW blower. Those cubic claims are listing figures for large ventilated spaces.
Is propane or butane the winter fuel?
Propane. Retailers say butane can freeze in a UK winter, and they specify the red cylinder for cold weather. Liquid Gas UK puts low-pressure propane at about 37 mbar and butane at about 28–30 mbar. Match the regulator to the cylinder and the data plate. A Bimson that prints 300 mbar or 700 mbar is not on a patio regulator.
Can I use a 15 kW garage blower in a small greenhouse?
Not as a stand-in for a 2 kW greenhouse heater. Reviews of the 15 kW Bimson describe garages, a workshop and a barn, with ventilation. In a small closed house the output is past the retailer frost band, the fan still wants a 13 A socket, and combustion products stay with the plants.
What if the allotment has no socket?
Both Bimson blowers drop out, because their fans are described with a 13 A plug. Choose a low-output greenhouse propane heater whose manual does not depend on mains, or look at the DAHTEC only as a battery-fan blower for an open non-domestic space. It is still 10 kW and unflued. No socket is not a reason to seal a polytunnel.
Do I need a thermostat and an oxygen depletion device?
On a 2–4 kW greenhouse heater, those are the controls shop listings use to hold a temperature and to shut the gas if oxygen falls. Calor’s Super Heat page names both. They do not replace a BS EN 50291 alarm or an open vent. These three blowers do not name an oxygen depletion device.
Related pages
Sources
Public UK sources named below. amazon.co.uk prices, stars and review counts on these three listings were taken from the listing files read on 20 October 2026. Page updated October 2026.
- RHS, heating greenhouses efficiently (retrieved 20 October 2026)
- Gas Safety (Installation and Use) Regulations 1998 (retrieved 20 October 2026)
- HSE domestic gas FAQ (retrieved 20 October 2026)
- HSE gas safety for employers (retrieved 20 October 2026)
- GOV.UK carbon monoxide (retrieved 20 October 2026)
- NHS carbon monoxide poisoning (retrieved 20 October 2026)
- London Fire Brigade carbon monoxide safety (retrieved 20 October 2026)
- Liquid Gas UK Consumer Guidance Sheet 39 (retrieved 20 October 2026)