Portable gas heaters - running cost?

[Martin Pentreath]

Does anyone have any information on this? I remember when I were a lad those calor gas fires on wheels were all the rage with students during the winter. But are they much cheaper to run nowadays than an electric convector heater?

(I'm aware of the issues of condensation and the need for ventilation. In fact looking back at some helpful chemical equations in the archives here, burning 1kg of gas produces about 1.5l of water. At that rate you'd really need to have the thing pumping out heat before the walls start dripping.)

[John Stumbles]

The increase in humidity caused by burning gas is likely to make it feel sweltering when an LPG heater is on but cold as soon as you turn it off again. If the heater is being used in ratty bottom-end-of-the-market accommodation which is likely to tend to damp anyway then an LPG heater will exacerbate the problem. For not much more than the cost of an LPG heater one could buy a dehumidifier which, by reducing the humidity, will make the place more comfortable at lower temperatures anyway, plus it'll chuck out about 250Watts (for a compressor type) which may be enough to keep the place warm much of the time anyway. Adding a cheap convector or radiant halogen heater should then cope with colder spells. Capital cost approx £100-120 for dehumidifier plus electric heater compared to c. £80 for LPG heater but should save on running costs fairly soon.

[Ronald Raygun]

No, I don't think they are, though they may previously have been.

Portable room heaters would typically use 15 kg Calor bottles (blue, hence butane). Wikipedia gives the heat of combustion of butane as about 46 MJ/kg. 46 MJ corresponds to 12.8 kWh. This size of Calor refill costs about £29 these days.

So the gas costs £1.93 per kg, and each kg gives the equivalent of

12.8 units of electricity, so the running cost is about 15 p/unit.

I pay less than that for my electricity, once I'm past the first

500 units per year which are more expensive, so I think electric heaters (convectors or others) win hands down, especially as they have no worries about condensation or carbon monoxide, and have a lower capital cost.

[Andy Champ]

It occurs to me that dehumidifier (to take water vapour, and make some heat) plus gas (to make some heat, and supply water vapour) might work quite well together.

But I'm scared of open fires in enclosed spaces. If _my_ boiler throws a wobbly it'll poison next doors cat that's sitting on the fence. An internal fire might poison me!

Andy

[js.b1]

A good one is about =A380, plus cylinder, plus gas which is quite a considerable cost. In reality you would most likely want two cylinders re backup if one runs out during a snowed-up spell like 2009 so you can choose when to go out rather than the heater.

A (very) powerful dessicant dehumidifier draws 390W (after the first

12hrs of not being used for some time), which is actually usable heating and very good for drying. Example: PREM-I-AIR PRDHZ8 on Ebay 120525881861 is about =A3119 delivered. It is actually well built, well thought out, not flimsy, a great many independent reviews around the net - and it is quieter than an x-dry on which it is I suspect genetically linked. A dessicant unit produces a fair amount of usable heating, but also works at low temperatures - that model is very good (I have had 17 dehumidifiers over the years and that one is only just below the Mitsubishi which is the only quality unit out there, the rest are just crap).

A good industrial electric heater is the 2kW industrial fan heater at about =A338.50 on Ebay - they use MICS (oven) elements, similar to fan oven motor & stainless impeller, and the thermostat actually does turn the elements on & off works too unlike the cheap nasty consumer fan heaters that crop up in winter. Actual power options are 650W 1300W

2000W (or thereabouts). There is a 3kW / 3.3kW version out there which is bigger, but on a 13A plug I am happier to take 2kW thanks. Cheap enough to buy two 2kW fan heaters, just run them off different sockets rather than the same double socket.