Best way to heat small building

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The building is single storey detached, built in the 1970's, and has electricity only - no gas. It is about 8m square, divided into several rooms. It will be used for sales and as offices.

What is the best way of heating the building? It will only be used in the daytime - say from 8am to 9pm.
 
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I would suggest electric panel heaters, set to come on before 8am via a timer, each with it's own build in thermostat. You could set the office to come on, before the other areas, as I would expect an opening time to public of maybe 9am?
 
Does it make any difference if they are oil filled or fan driven convector heaters?
 
Likely bottled gas and a gas fire it cheapest to run, can get oil fired space heaters but tend to go for silly prices, but safety wise and installation cost electric may be better.

The speed it heats is important, one is allowed an hour, but really you want warm within ¼ hour, fastest is inferred, then the fan heater, then convection heater, then panel heater, then oil filled radiator, the next consideration is safety, plinth heaters although really fan heaters are mounted where unlikely to be damaged or anything fall on it. Oil filler radiators are reasonably safe, seen a few fires with convection heaters where paper has fallen on the heater, or mounted upside down to cook sausage rolls on.

The common sense of people in the office is important, fan heater is designed to be flat on the floor, have seen a fire due to being mounted inside desk space to keep worker warm at 45° blowing down on their feet so sensor to switch off if over heated in wrong place.

I don't think I can say any heater is 100% safe, even the oil filled radiators found one where the thermostat bolted on the end bolts were loose so main section not earthed.

42kw-calor-gas-portable-cabinet-heater-fire-butane.jpg
the gas heater with built in gas bottle is around £95 and 4.2 kW so likely the cheapest easiest way, but it will make the room damp, a version with a flue much better, made mainly for caravans and boats, this one
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uses 35 sec gas oil, and does have the flue outside, and using blow hot air is fast.

Many of the caravan and boat heaters are technically not permitted for use in a building, due to size they do not comply with efficiency regulations for building heating, so technically you need house type central heating boilers converted to use bottled gas or oil fired, but oil and gas even bottled gas is so much cheaper than electric although designed for boat or caravan they are much cheaper to use than electric.

refleks.jpg
May not look the part in an office, and so may not work, but far cheaper than electric to run.
 
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Many of the caravan and boat heaters are technically not permitted for use in a building, due to size they do not comply with efficiency regulations for building heating, so technically you need house type central heating boilers converted to use bottled gas or oil fired, but oil and gas even bottled gas is so much cheaper than electric although designed for boat or caravan they are much cheaper to use than electric.

I did the bottled gas versus electric calculations a few years ago and then electric per Kwh was cheaper. It prove cheaper if the very large gas bottles are used, or a fixed gas tank.
 
Does it make any difference if they are oil filled or fan driven convector heaters?

Fan driven is likely to be better since there is less latency when trying to heat the place, but many people find oil radiators better as (anecdotally) they don't dry out the air so much.

Just make sure a thermostat is fitted.
 
I would generally never recommend an unflued fuel appliance inside. They create a lot of moisture, which if not disposed of (e.g. by venting the damp air and letting the heat out) will cause problems. Also, free standing gas appliances have considerable safety risks used indoors. Many insurance policies explicitly prohibit them.

But generally there is no such thing as "the best" option - only the best compromise.
A fanned appliance (e.g. fan heater) will heat the space fastest because it circulates the air. But they create draughts which causes discomfort, and when they switch off the air tends to cool very quickly - so the temperature tends to go up and down cyclically.
At the other extreme, things like oil filled radiators have significant thermal mass, so the temperature variations are much smaller - but they are much slower to heat the space up.

IMO, one of the worst options are the old fashioned "box of bricks" night storage heaters - we had them at a previous job in a rented office. You need to adjust the heat input daily according to the expectation of heating needs the next day. Then you tend to be warm in the morning, and either cold (because it's cold and the heat has run out) or hot (because the heat hasn't run out and the sun is now streaming in the windows) in the afternoon. And, as one of our members here points out, the difference between night and day rates has significantly reduced over the last few years making it harder to make night storage work effectively.

Whatever is chosen, good controls make a huge difference. Poor controls can make the temperature fluctuate, and that causes discomfort.
 
That's a heat pump - just by another name. If heating by electric, then in terms of running costs - the best option. But high installation costs.

An alternative heat pump setup would be an air-water outdoor unit, and a conventional wet heating system inside.

Many ways, as I say - you pick your personal choice of "best" set of compromises.
 
Thanks for all the suggestions; there's plenty to think about.

I had already discounted storage heaters for the reasons given by SimonH2.

I was not aware that oil filled radiators took longer to heat the space. I don't know if that is significant as most of the heating up will be done before anyone arrives at the building.

As for fanned heaters, having lived in two homes with warm-air central heating, I am well aware of the pros and cons of such a system - fast heating up; even faster cooling down. But, in this specific case, does this matter?

Costs, capital and running, are the overriding factors.
 

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