Patrick Dunford: Home Heating: Radiant Vs (Oil) Column Vs Convector

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I’ve always had predominantly or exclusively electric heating everywhere I’ve lived. There are quite a few different types of electric heaters available out there. The three types listed here are the best ones, in my view. I’ll briefly discuss the reasons for excluding other types:

  • Fan heater. The cheapest models seldom last more than one winter due to the motor seizing up. Why this is the case is a bit of a mystery, since portable cooling fans will last for years. And in fact, more expensive fan heaters can last much longer. Because it’s so difficult to be sure of the quality of what you are buying and because a fan heater has no real advantage over any other type, it is just easier to recommend against buying one. Don’t buy into the con that they can double as a cooling fan in summer – regular fans cost much the same, move more air and generally are much more durable.
  • Ceramic heater – a modern fan heater. Can be made smaller, but questions linger over whether the fan motor is any better quality than ordinary fan heaters.
  • Micathermic heater – just a modern type of radiant and briefly covered below.
  • Panel heater – this is really just another type of convector and will be discussed with the comments on that type below.

Obviously I didn’t mention heat pumps but I am talking primarily about portable heaters in the price range up to about $200. A heat pump is by far the cheapest electric heater to operate, but costs so much more and has to be permanently installed (although portable air con units are available).

So let’s compare the three types mentioned. The single biggest advantage all of them have is that with no fan or other wearing parts, they are very reliable and will give many years of service, and they are also very quiet. All types also have basic safety features like tilt switches and thermal cutouts and fuses fitted internally.

The oil column heater looks like the old style water filled radiator, except they contain oil instead. Electric elements are fitted inside and the oil is used to spread the heat more or less evenly over the surface area of the fins. The large surface area and the characteristics of the oil help to limit the surface temperature, which makes them quite safe. This is the most important characteristic, in my opinion, and why I prefer them for most applications. A rack can also be hooked onto the column for drying washing. Main disadvantages are being the most expensive of the three types compared, being heavy and therefore dangerous where kids could tip them over, and being relatively slow to reach full temperature (some of the modern ones are designed to pick up faster but at the risk of higher surface temperature). Because of that extra cost, oil columns are out of the three types the one that is most commonly produced in a range of sizes with different power outputs. They get pretty hot, enough to burn the unwary, although possibly not as hot as the top of a convector.

The radiant heater is like the old Conrays and the like that were the staple of many NZ homes in past decades. They have a built in reflector and radiant elements that produce mainly infra red heat (like the Sun) which has the big advantage of directly heating your body rather than the air in the room. This makes radiant heaters able to get to work very quickly and it also means its impact works the same even if you are in a very big or draughty space. Radiants also produce some convection heat from air passing over the reflector, and Goldair in particular have exploited this by designing some of their heaters with a grille on top to channel the air flow up. The main disadvantage with a radiant heater is how hot they get. The front of the heater is made of metal and can cause burns easily, and anything that is close to the front will also get heat up very quickly which is a big safety issue for children. Micathermic radiant heaters usually push out heat on both sides unlike most radiants that only heat to the front, so this type of heater can’t be placed close to a wall, whereas a more traditional radiant can be backed onto one.

Convector heaters out of these three types combine some of the advantages of an oil column with those of a radiant. Most convectors are just a simple vertical metal box that is easily folded in a factory and have vents both top and bottom. The internal element heats the air as it passes naturally through the box so hot air comes mostly out the top, although the sides will also get warm. Because of the simple design these are the cheapest of all three types, although fancy models with fans, electronic controls and other unnecessary features will push up the price.They produce full heat within seconds unlike an oil column and can be noticeably smaller. The main disadvantage is you can’t put a drying rack onto one of these, also the sides and especially the top get quite hot and so are a risk to children. Dimplex make something called a “Drytech” that appears similar to an oil column but is basically just a fancy looking convector and costs a lot more as the metal shape takes a lot more work to manufacture (the main reason for the higher cost of finned column heaters). Only advantage I can see is if I can hook a drying rack onto it. Panel heaters that some companies make are just basically a convector with the air vents in the front instead of top and bottom.

I have all three types in my house. Overall I prefer oil columns for most uses. I have one convector for any time I need heat quickly – I use it mainly to dry out the bathroom during my free hour of power every day, and it only cost $60 to buy. I am unsure what the great advantages of an oil column compared to a convector now are apart from the drying rack ability as they still get quite hot. Either type is best for a confined space as they mostly give out heat on the top, and the sides whilst hot to touch aren’t going to set anything on fire at 10 cm, so they can be placed close to a wall or other objects in a room as long as there is nothing directly above that can get toasted. I still have three radiant heaters bought for previous draughty or poorly insulated flats – still come in handy in a sleepout or shed, or for quick use in the kitchen for short period – but they spend most of their time in a cupboard now. Most portable electric heaters have hot surfaces which is a limitation when around children; the wall mountable types (panels and some convectors) could be put high enough to be out of toddlers’ reach). The air con is the only type of electric that doesn’t heat the air too much and so don’t dry it out as much as other kinds of heater.

If I was buying one today – it’d be a toss up between a convector or an oil column, depending on application. I’d expect both of these will have a long trouble free life of many years’ service. I do recommend if you are heating a room, to use a plug in timer and separate thermostat – the ones mounted in them are too close to the heat source to be effective. Both these additional devices can be hard to find – however Arlec currently have models which can be purchased from Bunnings.