Heater Types and Characteristics

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To complete my requirements for home heating this winter I have bought this Goldair convection heater. Of all the Goldair heaters I have owned this one has the roughest finish, with the metalwork actually being bent or misformed in several places. This heater has a fan which can operate on its own or with any heat setting. The fan itself is not noisy but can resonate the case making the overall noise level somewhat excessive. The heater pleases with its ability to output heat instantly without waiting for it to warm up. Like most Goldair models it has a 2 year warranty. As far as I can tell there is no tilt switch fitted to this model. For the smaller room in which it is going to be used it is much better at getting this space ready for use than the oil column in a short time frame. Like all metal painted heaters the smell will take some time to go away.
Now to fill this out I am going to describe the main types of electric heater and their characteristics, therefore their strengths and weaknesses.
Convection / Panel Heater
Typically an upright metal casing with air slots at the bottom to admit air and at the top to expel heat. Can be fitted with feet or wall mountable depending on design. Certain models are fitted with a booster fan to help improve air circulation. Heats the air in a room, so suitable where room is used by a number of people. Casing usually gets hot on all sides and adequate clearance is essential. There are a few heaters which have a solid panel and are often quite low powered like several hundred watts; intended to be left on all the time. Can have a long life due to simple construction and being made predominantly of metal.

Radiant Heater
These heaters give out infra-red heat which heats a person directly, they do this by having elements that glow red-hot. Used to be bare wire elements but modern types enclose these in a glass tube. A reflector helps direct the heat. The air in the room will also be heated by convection but only slowly. Most heat goes out the front but the casing can still get hot and clearance is important in such cases. Some types have a booster fan which improves the convection function by drawing air over one or more elements. Radiants can be made quite small and a half size (1000 watts) is more commonly found in this type of heater than any other. Some types are made to screw to a wall and can be mounted above head height in some cases. Useful where a room is being used by only one person and can give very fast personal heat. Can have a long life due to simple construction and being made predominantly of metal.

Fan Heater / Ceramic Fan Heater
An internal bare wire zigzag element has a fan directly behind it which blows the hot air out the front. All of the air passes through the fan unlike other heaters with a fan that is just a booster. This type of heater cannot be operated without the fan as the element would glow red hot and operate the safety cutout. Most modern types have plastic casings which keep quite cool so there is only a need to ensure enough clearance where the air blows out at the front and where it is taken in through vents. Fan noise is an issue in a lot of cases. Some modern fan heaters have ceramic elements and these make it possible to reduce the size of the heater. Fan heaters are often the cheapest kind available and also the least likely to last a long time. Available as a bathroom heater which is mounted to a wall and permanently wired in. Also can be available at 3000-4000 watts size or greater for heating a larger room or office which is wall mounted and permanently wired. Fan heaters often suffer from having the fan motor bearings seized due to dust in the air stream and it is not uncommon for very cheap heaters to fail after one winter’s use.

Micathermic Heater
An upright box containing a large sheet of mica which is the heating surface. Too new for me to say much about them. Some overseas reports have suggested durability and longevity issues. It is likely the mica carries a thin wire element spread over a large area. Because of the large heating surface this kind of heater can be made completely of plastic in some cases and is safer as the surfaces don’t get too hot.

Column Heater
A tall upright heater that works by convection.. Most commonly filled with oil surrounding an enclosed element, the column shape with fins gives a larger surface area to exchange the heat. There is now an oil-free column type available that is basically an adapted box convection heater with slots or holes cut top and bottom. Oil heaters’ strength is a low surface temperature with less risk of burning if touched, however they are very heavy and can injure if accidentally toppled by a small child. Oil columns take a while to warm up and therefore when heating up a cold room are pretty slow to get going. In order to achieve faster heating some models have a separate small element that directly heats air blown by a fan. Can have a long life due to simple construction and being made predominantly of metal.

Night Store Heater
A night store heater is specifically designed to store up heat into a slow release medium so that it is gradually dissipated during daytime hours. An example would be through heating up water which can then be circulated during daytime through radiators. Night stores make use of the fact that electricity can be obtained at a cheaper rate during offpeak time periods such as at night. A night store heater is permanently wired through a special meter and circuitry. Both oil columns and night store heaters use a two stage heat exchange system whereby the heat from the element is first transferred to an internal medium, such as liquid oil, which then releases its stored heat to the air. All other types of heaters mentioned here directly exchange heat with the air by passing it directly over the internal element. Night stores have the obvious limitation in that there is a limited timeframe in which the stored heat can be released. A school I am acquainted with uses a night store system to heat water which is circulated through radiators. It is of most value for an early morning preheat of classrooms and cannot be used throughout the day once the water has cooled.

General Comments
Different types of heaters suit different situations. Radiant heaters are very suitable for use by one person and give fast personal heat without waiting for the room air to be heated. They are well suited for use in large or draughty spaces where heating the air would be too slow. All other types of heaters work by directly heating the air. Portable fan heaters are also suited for similar applications but the radiant has as its chief advantage the lack of noise. Most kinds of heaters are intended for use in rooms where the heat is transferred to the surrounding air thereby warming everything in the room, this is best where there are rooms being used by more than one person, but it takes longer to warm up people. The fan heater tends to dry out the air and can upset some peoples’ respiratory systems due to this. The radiant heater’s principle metal surface is a chrome reflector which is less likely to cause smell than painted metal surfaces which especially in oil columns can take some days of use to fade away from new.

All heaters sold in NZ are required at a minimum to have a simple thermostatic overheat cutout which resets itself when the heater cools, this addresses the heater being tipped over or perhaps vents accidentally covered or failure of the fan in a fan heater. Many also have a thermal fuse fitted which permanently cuts off the power and is in addition to the resettable type. Tilt switches of various types can be fitted also and vary from a mechanical switch pressing against the floor surface to fully enclosed mercury switches. The latter are very sensitive to vibration and not really suited to use where there is movement or the heater is not perfectly vertical at all times. Many heaters are fitted with a built in thermostat that is in reality of very limited use due to being affected by the temperature of the heater itself. Portable heaters made for the Australian market are often quoted at 2400 watts. When used in NZ, due to the lower mains voltage the maximum output is around 2200 watts or an equivalent proportion at lower power. Electrical safety authorities in NZ now recommend that portable heaters are not used with extension leads or plugboxes due to the risk of the high current draw damaging these, this in my view is down to the fact that current safety standards allow very poor quality plugboxes and extension cords to be sold in NZ. It is also recommended that use of timers to turn the heaters on and off at specific times is not done. I used to use a timer to turn on an oil column heater in my bedroom to warm it up prior to my alarm on cold mornings. This wasted a lot of power so now I just use a radiant heater without a timer. The most useful accessory for any portable heater in my opinion is a countdown timer, the ones made by HPM give a maximum of 2 hours operation and this avoids forgetting to turn the heater off so it is a good power saving and safety measure. I don’t worry about plugboxes as I always buy the higher quality ones.

As I noted this winter I have deliberately gone away from oil columns which I used to use a lot, due to their limitations – having moved to different rental accommodation and finding various limits such as draughtiness – as well as desiring to eliminate warm up delays and therefore save power when the heater is not being used for long periods. For example a radiant heater in the bedroom is more efficient when it is only needed when getting out of bed and dressing. A convection heater in the study brings it up to temperature very quickly without wasting time. A big radiant in the living room helps counter air draughts around the entrance door. A fan heater in the kitchen-laundry provides effective spot heating despite the mandated open window letting cold air in. And so on.
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