Kotatsu Heater Guide

Kotatu Heaters

こたつヒーター

Kotatsu Heater Guide

So maybe you love Kotatsu but you don’t want to fork out for a whole ready made set up. Maybe you like DIY projects. Or perhaps you already have a Kotatsu but the heater has stopped working. Rather than buy the whole thing all over again, you may be thinking it’s better just to change over the heater.

If you are looking at what you might want to combine your table with in the room, we have a post on the Japanoscope Japanese Home Decor page.

If you’re interested in complete Kotatsu sets, check our page here.

How To Make Your Own Kotatsu

Well, you can always just grab a Kotatsu heater and attach it to the frame of a table and put a piece of wood on top.

Another easy way to make your own Kotatsu is to use any kind of table that has a shelf built into it underneath. You can take off the shelf part and swap to using it as a table top, with a blanket or futon sandwiched beneath it and the original table top. The most popular choice for this is the Ikea Lack, because it has short legs, a shelf that can easily be put on top of the table top, and is readily available from a range of locations.

You can see instructions on this here.

IKEA Lack

This is probably the most popular used for doing an easy Kotatsu conversion.

How To Change Over A Kotatsu Heater

Find the size of the frame that holds your current Kotatsu’s heater

Since the year 2000, Kotatsu heater sizes have largely been standardised at 29 x 29cm. Some Kotatsu frames are 33x33cm, but most heaters will come with a space filler so that you can still fit your 29x29cm heater. 

From there it’s really just a matter of unscrewing a couple of screws on each side of the heater and slotting in the new one. For most Kotatsu, the whole procedure shouldn’t take you longer than around 10 minutes.

This site has more information in Japanese that you can hit translate on if you want.

How To Choose A Kotatsu Heater

Size

In addition to making sure your Kotatsu heater is the right size to fit your table frame, you also need to make sure that the heat the heater emits matches the general size of your Kotatsu set. Generally speaking, kotatsu sizes don’t vary so significantly that you need to worry about it too much. 

The other thing to look out for is how thick the unit is. Obviously, the thicker it is, the more it sticks out under the table and the more annoying it will be. So thinner is better. Sizes range from 4cm (1.5 inches) on the slim side to about 7-8cm (around 3 inches) for thicker kotatsu heaters.

 

Wattage

Wattage is related to sizes. Wattages are most commonly around the 600w mark, which is generally sufficient for most Kotatsu.

 

Be aware there are some smaller Kotatsu Heater units that are made specifically for single person Kotatsu applications that are as low as 100w. These are not going to be warm enough for a family size Kotatsu.

 

One advantage of lower wattage Kotatsu heaters is that you can leave them running for a long time, perhaps coming and going from the kotatsu, and not have to worry too much about power costs. Some people also say they have greater peace of mind by using a lower wattage kotatsu heater because they worry less about the worry of fires.

Of course the best way to get the best of both worlds is to have a Kotatsu with an adjustable heat dial, which most modern units have.

 

Quartz Vs. Halogen Kotatsu Heaters

Both Quartz and Halogen are good options for Kotatsu heaters. Generally speaking, halogen heaters are more energy efficient and longer lasting than Quartz. If you want to read about the details of the difference between quartz and halogen check out this article.

Do kotatsu heater casings get hot enough to burn?

Kotatsu heaters are specifically designed to not get so hot that they will burn. Make sure you get a heater that is specifically made for a Kotatsu. 

That being said, it is possible to sustain a low level temperature burn if you leave your body on a heated surface for extended periods of time.

Is a kotatsu a fire hazard?

 

Kotatsu do not represent a significant fire hazard if used correctly. Modern Kotatsu generally have automatic temperature adjustment functionality. In 2017, there were four reports from the Tokyo Fire Department of fires linked to the use of Kotatsu. 

There have been cases where incorrect use of Kotatus has led to fires. These are often associated with different items being pushed inside the Kotatus cavity, such as laundry or flammable items that can ignite if in contact with the heating apparatus too long.

The top things to be aware of when using a Kotatsu from a safety perspective are:

 

(1) Keep cushions and clothes out of the kotatsu

(2) Don’t put furniture on the power cord

(3) Arrange a cord in a way that it is not constantly getting stepped on and damaged

(4) Prevent dust from accumulating on the heater of the electric kotatsu, which can build up and become flammable over time

(5) Turn off the power when not using the kotatsu

 

As with any kind of heating, using a kotatsu demands a level of awareness.

Can you burn yourself on a kotatsu?

It is possible to sustain low temperature burns from long contact with a kotatsu heating apparatus.

Low temperature burns are those caused by heat sources below 60 ° C. For every 1 degree increase in temperature, the time it takes to get a low temperature burn is roughly halved. If you were to touch something at 44 ° C for 6 hours, you run the risk of getting a low temperature burn.

Low-temperature burns tend to cause burns that run deeply into the skin. Legs, ankles, and heels are particularly susceptible to low-temperature burns as these areas of the body do not perceive pain as acutely as others and often have poor blood circulation. 

This means people should take care in spending too long in a Kotatsu, such as sleeping for long periods of time.

Do you need a Power Converter for a Kotatsu heater?

It is possible to use a 100v Japanese Kotatsu in the U.S. which has 120v power, but it is not recommended. This is because the device will tend to overheat if you turn it up higher than its lowest operating levels. Some people do it, but you need to balance up the  slight inconvenience of using a power converter with the risk you are taking of using a device with a power source it was not designed for.

What converter would you use for a kotatsu heater

Voltage in Japan is 100v, so if you buy a Japanese made Kotatsu you would need a power converter or transformer to convert to 120v for North America, 230v for Central Europe or 240v for Australia.

Metro 600w Kotatsu Heater

A reliable, standard slim size Kotatsu Heater. Hard to go wrong with this one.
Pros
Standard Size fits most modern kotatsu 29cm x 29cm
Easy install with screwdriver
Slim depth at 4.1 cm (1.6 inches)
U-shaped quartz tube heater heats the square space completely
Heat level controller
3m cord
Efficient power usage. High = about 180 Wh, Low = about 70 Wh

Cons
Needs 600w power converter
No remote control

YAMAZEN kotatsu Heater Unit 510w

Pros

Simple, functional heater.

  • Standard Size fits most modern kotatsu 29cm x 29cm
  • Includes fan for distributing heatEasy install with screwdriver
  • Moderately slim depth at 5.8cm (2.28 inches)
  • U-shaped quartz tube heater heats the square space completely
  • Temperature regulation: temperature control knob stepless variable (body)
  • 3m cord
  • Efficient power usage. High = about 180 Wh, Low = about 70 Wh

Cons

  • Temperature controller design very basic
  • Needs power converter
    No remote control

Morita Kotatsu Heater 600W

Japanese brand Kotatsu heater designed for Chinese market

Pros

  • Standard Size fits most modern kotatsu 29cm x 29cm
  • No-tool installation
  • Medium slim depth at 5 cm (2 inches)
  • Heat level controller

Cons

  • Heat level controller on device body is difficult to access
  • Needs power converter
  • No remote control

METRO one person kotatsu MPQ-100 (N)

A uniquely designed single person Kotatsu heater that you can slip under and blanket for an instant, simple Kotatsu experience.

Pros

  • No set up required
  • Use with just about any blanket
  • Beautiful wooden design

Cons

  • Very low wattage 100w
  • Only works for very small spaces such as under a one person blanket

So if you need to change over you Kotatsu Heater, or want to make your own. Don’t fret, it’s not so hard. Grab any of the heaters above and give it a burl.

If you are looking at what you might want to combine your table with in the room, we have a post on the Japanoscope Japanese Home Decor page.

If you’re interested in complete Kotatsu sets, check our page here.

Japanoscope is a registered affiliate with several online shops and may receive a commission when you click on some of the links within content.

Who is behind this site?

I’m Peter Joseph Head. I lived in Japan for four years as a student at Kyoto City University of the Arts doing a Masters Degree, have toured the country six times playing music and speak Japanese (JLPT N1). I’ve written songs in Japanese and have released several albums through Tokyo label Majikick Records.

ピータージョセフヘッドです。4年間京都市立芸大の大学院として日本に住み、6回日本で音楽ツアーをし、日本語能力試験で1級を取得しました。要するに日本好きです。

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