Heating, heaters, types of heat.
Published 27 May 2021
Types of heat explained
Heaters, heating, heat - understanding how heat is transferred will help you choose the right heating for your home.
In this post, we’ll run you through what to look out for and (hopefully) help you find the best heater for your home.
Heat is created and transferred in three ways: conduction, radiation and convection.
Conduction heat
Conduction heat is when two solid surfaces touch. This is why metals are great conductors of heat, but gasses are not (gasses are better insulators because gas moves around more freely. Double-glazing, double-layered curtains and honeycomb blinds are good examples of this).
Examples of conduction heat include touching a stove and being burnt and ice cooling down in your hand. Heat is being transferred from one surface to another.
It is not possible to heat a room with pure conduction heat. It needs to be paired with something that produces radiant heat.
Radiant heat
Radiant heat is what happens when heat travels by radiation in the form of waves. It works by transferring heat from a surface that is hot to a surface that is cooler.
Radiant heaters heat people and objects, not the air - giving instant comfort like the sun or an open fire. They work best in larger spaces, where it might be difficult or not economical to heat the space (warehouses, patios, outdoor bars).
Because radiant heaters warm up surfaces when placed at ground level, they transfer heat to the floor. When a surface is warm it gives off radiant heat to other surfaces that are cooler. Certain solid surfaces, like metals, hold heat for much longer.
Picture this: A metal chair left out in the hot sun absorbs radiant heat. If you sit on the metal chair and it feels hot, that feeling is heat being transferred to you by conduction.
Convection heat
Unlike radiant heaters (which heat objects), convection heaters directly heat the air. They work by pulling cold air through the bottom of the heater, past a hot panel or element and pushing it out through the top. As hot air rises it pushes cold air down, the cold air is then sucked back into the heater and the process repeats until the room hits your chosen temperature. Convection heaters are good for rooms and offices.
If you live in a multi-story house, the top of the house will feel warmer than the bottom as hot air rises. Convection heaters work best when there are no draughts/spaces for heat to escape.
What do we recommend and why?
As a general rule, we recommend heaters that combine radiant and convection heat. A heater like the Atlantic Solius is the preferred option as it gives off 70% radiant and 30% convection heat.
If you have a heat pump, but heat isn’t reaching a part of the room these heaters are a fantastic top-up option. Alternatively, if a heat pump is not an option for your home and you’re trying to heat a space that is more that is 25 sqm, two of these heaters at opposite sides of the room will create a warm and even heat spread.
Other types of heaters
Micathermic heaters - like the Dimplex 2kW & the Kent 1.5 kW / 2 kW heaters.
If the Atlantic Solius isn’t a financially viable option for you, we also recommend the Dimplex 2kW and the Kents as good alternatives.
Like the Atlantic Solius, these heaters utilise both radiant and convection heat. The big difference is the Dimplex produces 70% convection and 30% radiant heat while the Kent produces 80% convection and 20% radiant heat.
Both use micathermic technology to produce heat. Micathermic technology is a fancy way to say that the heating element is encased in thin sheets of mica (a mineral that holds heat really well).
Heat pumps
Interesting fact: heat pumps don’t create heat. They work by moving available heat from one place to another.
They work by pulling heat energy from the outside unit (yes, even on the coldest days) and then running that energy through a piping system that expels warm energy into the home.
In summer the reverse happens. Heat energy is pulled from inside the house and pushed outside. That’s right, heat pumps and air conditioning units are the same thing.
Heat pumps are the best option for heating your home. The climate you live in does determine the type of heat pump you need. If you’re not sure which one is right for you, get in touch.
Oil heaters
It’s in the name. Oil fin/column heaters work by heating the oil that is encased in the heater and then transferring the heat through the metal wall. They work via convection.
We don’t recommend these heaters because they take a lot of energy to produce heat. This is because the oil has a high boiling point and it loses heat very quickly. Simply put oil doesn’t like to be heated.
Fan heaters
Fan heaters work by using a fan to pass heat through a heating element. You feel the warmth much faster with a fan heater, but the amount of energy it uses to heat a room makes it really expensive to run. Remember hot air rises (and so will your power bill).
We don’t recommend fan heaters either.
Frequently asked questions
What size heater should I get?
For radiant heaters - you need about 80W of heat per sqm ([sqm of the room] x 0.08 = how many kW of heat you need).
1kW radiant heater – 15 sqm
1.5kW radiant heater – 15 to 20 sqm
2kW radiant heater – 20 to 25 sqm
For convection heaters, you need around 65W per m3
1kW convection heater – 15m3
1.5kW convection heater – 23m3
2kW convection heater – 31m3
2.4kW convection heater – 39m3
Note - convection heat requires more energy as it heats the air, whereas the cubic meterage of a room doesn't have as much of an impact on radiant heat because radiant heat only heats surfaces.
For micathermic heaters, you need 100W of heat per sqm
1.5kW micathermic – 15 sqm
2kW micathermic – 20 sqm
2.4kW micathermic – 24 sqm
What is the difference between cost-efficient vs energy-efficient?
All portable heaters produce the same 1kW electricity to 1 kW of heat and cost the same to run (if the same kW size, and on for the same time). Efficiencies are made in how the heat is distributed. A mixture of radiant and convection heat will heat your space more evenly and faster. Convection heat rises (air) and radiant heat stays low (on surfaces). Having a heater that does both is a win-win.
You would need a 1kW Soilus Heater to heat the same size room as it uses roughly half the energy required as convection heat.
What is infrared heat?
Infrared heat is pretty much the same as radiant heat. The term ‘radiant’ tells you that some kind of radiation is used to heat up a room, whereas ‘infrared’ specifies that infrared radiation produces heat. In a nutshell, the radiation we perceive as warmth is infrared heat.
Got a question? Flick it to customersupport@sustaintrust.org.nz