Heating cold space: Oily Rag column for 1 July 2013

Heating cold space

By Frank and Muriel Newman

Choosing a heater is about as confusing as confusing can get. The secret is to understand a little about the different types of heaters, and then buy one that suits your needs and your oily rag pocket. There are basically three different types of heater to consider: radiant and fan heaters, oil-filled or convection panel heaters, and climate-based heating systems. 

Radiant and fan heaters use an element and a reflective surface to provide spot heat, and some have a fan to propel the heat. They are convenient in that they are portable and cheap to buy, but (there is always a “but”) they are inefficient and therefore expensive to use. Natural-gas radiant heaters are cheaper to operate, but if one takes into account the additional cost and shorter life of gas appliances and their need for regular maintenance the savings are dubious.

Oil-filled or convection panel heaters are passive heaters in that they gently heat the air. They do not provide a blast of hot air (as do radiant and fan heaters) but are an excellent way of heating a room. Most come with a thermostat and timer. Thermostats control the amount of power your heater uses by switching on and off to maintain your desired room temperature. Timers automatically turn your heater on and off at times that suit your needs. In other words they use less power, and give you more control over room temperature at the most efficient times.

Climate-based heaters are in effect air-conditioning units in that they pick up the natural heat from outside your home and pump it inside. In summer they work in reverse to cool your home. The advantage is that they are cheap to run, costing about half as much as other heaters, but they are expensive to buy.

To summarise, if you want to heat a room look at an oil-filled type heater. If you want a quick blast of hot air, then a standard radiant heater is for you. Those who don’t mind spending big bucks up front should look at a climate-based heating system.

Having decided on the type of heater that best suits your needs, the next task is to decide the right-sized heater for your room. This is not all that difficult to calculate.

Heaters come in different kilowatt sizes. To determine the number of kilowatts you need, measure your room in cubic metres and multiply by 35. For example, if your room has a floor area of 6 x 4 metres and a 3 metre stud height, then it measures 72 cubic metres. It takes 35 watts to heat a cubic metre so multiply 72 cubic metres by 35 watts and you get 2520 watts, or 2.5 kilowatts (1000 watts = 1 kilowatt). You will need a 2.5 kilowatt heater.

Measure one of the rooms in your home to do the calculation yourself.

Step 1. Length x width x height = cubic metres of room space.

Step 2. Cubic metres of room space x 35 watts = total watts required.

Step 3. Total watts required divided by 1000 = kilowatt heater required.

            Step 1.    .......  x  .......  x  .........   =  ..........

            Step 2.  .......  x  35 watts  =  ..............

            Step 3.   ..........  / 1000     =  ........... kilowatt heater

Here are a few other space heating tips:

·         For those who have water-heated radiators, pin or staple kitchen foil behind the radiator. This deflects the heat into the room rather than allowing it to heat the wall.

·         Use a timer on oil heaters. Have it turn the heater on a couple of hours before you get up in the morning.

·         Reflectors in heaters should be kept clean and bright.

·         Using an open oven as a space heater is expensive and downright unoily-raggish.

Do you have a favourite winter tip you would like to share with readers? If so, please send it to us at www.oilyrag.co.nz or write to Living off the Smell of an Oily Rag, PO Box 984, Whangarei.

*Frank and Muriel Newman are the authors of Living Off the Smell of an Oily Rag in NZ. Readers can submit their oily rag tips on-line at www.oilyrag.co.nz. The book is available from bookstores and online at www.oilyrag.co.nz.

ENDS

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