15kw heater running cost: what a full hour costs you

A propane blower at £75.99 and an electric blower at £186.15 sit on the same amazon.co.uk shortlist. In a cold workshop the lower till price looks like the cheaper winter. The bill that repeats is the fuel, and you can multiply it before you buy.

The 15kw heater running cost at full output is about £3.95 an hour for 15 kW of electricity, and about £3.82 an hour for propane at 1.09 kg per hour when a 13 kg refill costs £45.50. About 13 pence separates those two hours. A 6 kg refill at £32 turns the same burn into about £5.81 an hour. The till price hides that split.

Ofgem’s average Direct Debit unit rate for 1 October to 31 December 2026 is 26.32 pence per kilowatt-hour in England, Scotland and Wales. Calor’s published refills used here are £45.50 for 13 kg of propane and £32 for 6 kg. Both gas listings in the 15 kW fan heater comparison state 1.09 kg/h, and the electric listings state 5, 10 and 15 kW. Products Compared has not lab-tested these heaters. A qualifying purchase through a link on that comparison can earn us a commission, at no extra cost to you.

In short

A 15kw heater running cost at full output is about £3.95 an hour on the domestic cap, or about £3.82 an hour from a £45.50 refill for 13 kg of propane at 1.09 kg/h. A £32 refill for 6 kg is about £5.81 an hour at that same burn rate, so the smaller bottle can be the dearer hour. The 5 kW and 10 kW electric steps are about £1.32 and £2.63. The standing charge stays out of every one of these sums.

The two bills behind a 15kw heater running cost

The listing price is paid once. On that shortlist the DAHTEC IFHO3-150G is £186.15 in black and in silver, the DAHTEC BGA1401-15-18 gas blower is £84.15, and the ALINI ALINI15GH is £75.99. The electric machine costs £110.16 more than the ALINI and £102 more than the DAHTEC gas blower. You pay that gap on the day you buy.

At full output on a 13 kg refill, the hours nearly meet. Fifteen times 26.32 pence is 394.8 pence, about £3.95. Propane at £3.50 a kilogram, which is £45.50 divided by 13, times 1.09 kg is £3.82. A workshop heater electricity bill for forty hours, five days of eight hours, is £157.92 on the electric blower or £152.60 on that propane. The propane week is about £5 cheaper, so the money saved at the till is still there.

A 6 kg refill reverses the week. Forty hours at £32 a bottle, still at 1.09 kg/h, come to about £232.53, about £75 more than the electric week. About £75 of the £110.16 saved on the ALINI is spent again on fuel after one such week, and the rest is gone after about 59 hours. Shelf prices on amazon.co.uk move, so repeat the sum with the price on your own paperwork.

Electricity at 5, 10 and 15 kW

The 15kw electric heater cost per hour is the step times 26.32 pence. Five kilowatts are 131.6 pence, about £1.32 an hour and £10.53 over eight hours. Ten kilowatts are 263.2 pence, about £2.63 an hour and £21.06 over eight hours. Fifteen kilowatts are 394.8 pence, about £3.95 an hour and £31.58 over eight hours.

The 5 kW versus 15 kW running cost is threefold while both steps stay flat out. Only the £31.58 day at 15 kW sits next to eight hours of propane at about £30.52 on the 13 kg price. Eight hours at 10 kW is about £21.06 against that same propane. The gap opens as soon as you step the electric heater down.

The steps sit on a 400 V heater. The DAHTEC bullets require 380–400 V three-phase and rule out a household socket. A 13 amp plug at 230 volts carries about 3 kilowatts, and 5 kW at 230 volts is about 22 amps. With only that plug, price a smaller heater in the plug-in fan heater comparison.

The thermostat can shorten time at full power, and it leaves the price of each kilowatt-hour alone. A workshop that reaches the setting pays only for the fraction of the hour the heater drew. An open workshop that never gets there still pays near £3.95 at 15 kW, or fifteen times the unit rate on your bill.

Propane at the listed 1.09 kg/h

Both gas listings put the propane heater kg per hour at 1.09. The ALINI page names propane, includes a regulator and a 1.5 m hose, and a review says the flow cannot be turned down. The DAHTEC gas page leaves the fuel-type field empty, ranks with propane heaters, and says the flame is adjustable while still printing only 1.09 kg/h. A quieter flame has no second figure to price.

Calor’s £45.50 refill for 13 kg is £3.50 a kilogram. Times 1.09, the hour is £3.82 and the bottle lasts about 11.9 hours, near 11 hours and 56 minutes. One eight-hour day fits, with about 3.9 hours left. The £32 refill for 6 kg is about £5.33 a kilogram, about £5.81 an hour, and lasts about 5.5 hours, so it empties during that same day.

Divide your own refill price by the kilograms, then multiply by 1.09. The Calor pair is a public comparison of bottle size, not a weighed test beside the bench. If the DAHTEC flame turns down, £3.82 is only the printed rate. Gas heaters outside this 15 kW set are in the gas heater fan comparison.

What this arithmetic leaves out

The standing charge stays out of every hour above. It remains when the heater is off, and a second blower does not add another one. Folding that daily line into one working hour bills the heater for a fee that does not depend on it. The hourly column is the unit rate times the kilowatts, or the price per kilogram times 1.09.

The 26.32 pence average is Direct Debit in England, Scotland and Wales from 1 October to 31 December 2026. A business contract can sit above or below the cap, and this page does not invent a commercial rate to fill the gap. Northern Ireland, prepayment and a fixed deal each use the rate on that bill. After 31 December 2026, keep the kilowatts and insert the new pence.

The propane fan also draws mains power. ALINI states a 230 V UK 3-pin plug for it. The DAHTEC gas listing says AC and states neither the voltage nor the fan’s watts, so that extra is missing from £3.82. The figure of £3.95 also leaves out an electrician’s charge for bringing 400 V to the bench.

A propane blower burns fuel in the space it heats. The hourly sum does not settle the ventilation that burn needs. That part of the choice is on the electric or gas page.

Where to choose the machine

With 400 V already installed and 13 kg refills near £3.50 a kilogram, full output costs about the same per hour on either fuel, and the gas blowers cost £102 to £110.16 less to buy. Electricity is about 13 pence an hour dearer, so the purchase gap stays with the gas buyer. On £32 refills of 6 kg the electric hour is lower by about £1.86, and the extra £110.16 over the ALINI is matched in about 59 hours, a little over seven eight-hour days, while those prices hold.

At 10 kW, electricity is about £2.63 an hour against about £3.82 of propane held at 1.09 kg/h. At 5 kW it is about £1.32. Price the propane at the printed burn unless your manual states a lower rate you will use. A 13 amp socket removes this electric blower before that sum starts, and a room that needs a heater under about 3 kW belongs with plug-in machines.

There is no tested winner among the four listings. The electric colours share one thin review, and the gas heaters are another fuel with a fan on the mains. Shelf price, steps and burn rate are set out on the same 15 kW fan heater comparison.