Life Hacks in Japan

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"Life in Japan 2023" We found the safest and most energy-efficient heating system!

Before introducing our heating recommendations, we provide a brief overview of safety and thermodynamics. If you are in a hurry, please click on the table of contents to skip to the next page.

safety

Energy sources are divided into three categories: electricity, oil (kerosene), and gas.

First, we will discuss oil- and gas-fired heaters, such as oil stoves and gas fan heaters. The most common type of heating appliance is the "open combustion appliance," in which combustion air is drawn in from the room and exhaust gases are also discharged into the room.

Combustion appliances | Propane Gas Rate Consumers Association

 

While open combustion appliances are easy to use because they can be placed anywhere, they also greatly increase indoor carbon dioxide levels. If oxygen levels drop with prolonged use, the risk of carbon monoxide poisoning also arises.

In the oil fan heater, the CO2 concentration rose rapidly after the start of heating operation, and exceeded 5500 ppm, the limit of measurement of the meter, after 30 minutes. This concentration level greatly exceeds the standard value of 1000 ppm specified in Article 129-2-6 of the Building Standard Law Enforcement Order.
Experimental Study on the Influence of Different Heating Appliances on Whole Body Warming and Cooling Sensation - Study on Ensuring Comfort in Living Space in Detached Houses

Effects on the human body for each carbon dioxide concentration
350-450ppm
0.035-0.045%vol
Fresh air
600-1200ppm
0.06-0.12%vol
Indoor Air
>1000ppm
>0.1%vol
Fatigue and difficulty concentrating appear.
5000ppm
0.5%vol
Maximum allowed in an 8-hour (working day) office
38000ppm
3.8%vol
Breathing (direct)
>100000ppm
10%vol
Vomiting sensation, loss of consciousness and death

Relationship between Carbon Dioxide (CO2) Concentration and Indoor Air Quality, ROT21-01|Dew Point Meters and Oxygen Analyzers Michel Japan K.K.

 

 

In addition, both oil and gas continue to produce water vapor as they burn, which can lead to excessive humidity if used for long periods of time. Simply put, burning one liter of kerosene produces about one liter of water. As a result, a lot of condensation occurs, which is one of the causes of mold. (See below for more on the air conditioner drying problem.)

Fuel Type CO2 production Water vapor production
kerosene 144 liters 0.120 liter
Natural gas (13A) 109 liters 0.161 liters
propane gas 123 liters 0.132 liters

How much CO2 and water vapor is produced when gas and oil are burned? | Mitsubishi Electric Frequently Asked Questions FAQ

 

Furthermore, studies have shown that oil fan heaters release a wide variety of pollutants generated during the combustion process into the room.

We conducted an actual measurement survey during the use of oil fan heaters to clarify the actual condition of air pollution.

-omission-

The study yielded the following findings

1: Actual indoor pollutant concentrations (measured survey)

-omission-

b. The concentration of indoor VOCs (volatile organic compounds) such as heptane, toluene, octane, nonane, decane, nonanal, undecane, decanal, dodecane, tridecane, and tetradecane increased with the use of the equipment, with decanes in particular showing a significant increase in concentration.

c. NO2 concentration was 395 ppb after 50 minutes of use, 6.6 times higher than the ambient air quality standard under the Air Pollution Control Law.
Study on Indoor Air Pollution during Use of Open Oil Heating Appliances - VOC, NOx, and NH3 Emission from Oil Fan Heaters -.

 

For these reasons, we recommend using heating equipment that uses electricity, unless there are circumstances where there is no electrical outlet or the maximum wattage that can be used is exceeded, not to mention the comparison of running costs.

Method of converting electrical energy into thermal energy

The direct or indirect conversion of electrical energy into thermal energy for use in heating or cooling objects, etc., is called electroheating, which can be divided into eight different methods. Of these, the following three are used for heating equipment.

resistance heating

This method uses the heat (Joule heat) generated by passing electricity through a heating element.


Resistance Heating | Japan Electro-Heat Center

 

 

"When a steady current is applied to a conductor, the amount of Joule heat generated in a given time is proportional to the square of the magnitude of the current and the resistance of the conductor. This law is called "Joule's law.

Each conductor has its own inherent resistance, but no matter what material the conductor is made of, the amount of heat generated when a current is applied to it is all determined by Joule's law.

Heating elements include metallic and non-metallic heating elements, each of which has its own specific resistance. Various materials with different heat resistance and corrosion resistance are used as heating elements, depending on the temperature and atmosphere in which they are used. The table below lists the main types of heating elements.

  type Maximum operating
temperature (℃)
20°C Resistivity
(μΩcm)
feature
metal Iron, Chrome, Aluminum 1,100-1,400 123-160 Excellent oxidation resistance, poor toughness
nickel-chromium 1,000-1,200 108-112 Most popular, high temperature strength, good molding
molybdenum (Mo) 1,800 5 High temperature use possible, reducing atmosphere required
tungsten (W) 2,400 5.5 Can be used at very high temperatures, reducing atmosphere required
nonmetal silicon carbide (SiC) 1,650 20000
(1,000℃)
Most widespread nonmetal, unsuitable for intermittent use
molybdenum silicide 1,800 30 High bending strength, weak thermal shock resistance
lantern chromite 1,800 110000
(1,500℃)
Inferior thermal shock resistance
carbon 2,600 8 Can be used at very high temperatures and is resistant to rapid heating and cooling

Principles of Resistance Heating | Japan Electro-Heat Center

 

Infrared and far infrared heating

This is one of the heating methods that utilize thermal energy from infrared and far-infrared radiation. Infrared radiation is located between visible light and microwaves, with wavelengths ranging from 0.78 μm to 1 mm. The wavelength range of 3 µm to 1 mm is called far-infrared radiation.

Near-infrared rays are wavelengths that heat metals, while far-infrared rays are wavelengths that heat non-metals. Far infrared rays are effective in heating the human body, which is a nonmetal.


Infrared and Far-Infrared Heating | Japan Electro Heat Center

 

Ceramic materials are currently the only materials that absorb far-infrared radiation well and are heat resistant. Most far-infrared heaters have a surface composed of ceramic material with an electric heating wire inserted inside. When energized, the surface temperature of the heater typically rises to several hundred degrees Celsius, radiating far-infrared radiation.

heat pump

See below.

 

 

Heat transfer

You may often see the division into conduction heating, convection heating, and radiant heating, but what is the difference?

Heat is always transferred from a place of higher temperature to a place of lower temperature (Second Law of Thermodynamics). There are three types of heat transfer: conduction, convection, and radiation.

conduction

The direct transfer of heat to a heated object in contact with a heat source is called conduction. Conduction also occurs when heat is transferred from a hotter part to a cooler part inside a heated object. The ease of heat transfer (thermal conductivity) differs depending on the substance. In general, metals have high thermal conductivity, while wood and plastic are materials with low thermal conductivity.

 

convection

Heat transfer through the movement of fluids such as gases and liquids is called convection. A heated fluid expands, becomes lighter and rises, while a cold, heavy fluid falls. This process is repeated to transfer heat to the entire fluid. Heat is transferred to the object being heated through the medium of the fluid. Convection is characterized by the fact that heat is transferred with the movement of matter, the fluid.

 

Radiation (radiation)

The transmission of heat by electromagnetic waves emitted by a heat source is called radiation (radiant). A material radiates electromagnetic waves according to its temperature. A high-temperature heat source radiates strong electromagnetic waves, which are converted to heat when absorbed by the object being heated. Since electromagnetic waves can be transmitted even in a vacuum, heat can be transferred to remote locations without the mediation of other substances.

 

Although we have introduced three ways of heat transfer: conduction, convection, and radiation, objects are heated through gases and liquids that are heated by contact with a heated object (conduction) or by infrared radiation "radiated" by the heated object (convection).

So, except in a special environment such as a vacuum space, there is no way that only one of them can transfer heat.

 

 

Electromagnetic waves and far-infrared radiation

Electromagnetic waves are classified from the shortest wavelengths into gamma rays, X (X) rays, ultraviolet rays, visible light, infrared rays, microwaves, radio waves, and others.

The energy contained in electromagnetic waves is converted into heat when absorbed by matter. Conversely, every object on earth that has a temperature above absolute zero always emits infrared rays with wavelengths corresponding to its temperature. When the temperature of an object reaches 1000 K (727 °C), it begins to emit visible light and appears to glow red. As the temperature increases further, the object emits shorter wavelengths of light.

No electromagnetic waves and heat

 

For metals, halogen heaters are effective for heating because radiation with shorter wavelengths generally has higher absorption rates. Heating with far-infrared heaters can reach a certain temperature (several hundred degrees to about 1000°C), but not up to the heating temperature of halogen heaters (about 2000°C). Incidentally, halogen heaters also emit more far-infrared radiation than far-infrared heaters, so they do not heat only metals and not other metals. The share only becomes smaller as shown in the figure below.

About Far-Infrared and Near-Infrared Radiation | Japan Heater Co.

 

The differences between heaters are shown in the table below. As shown in the previous graph, whether near-infrared rays are also emitted or only far-infrared rays are emitted is mostly determined by the temperature of the heating element, not the material, so even if a halogen heater were used, only far-infrared rays would be emitted if the output were reduced.

Don't misread the life expectancy, it is true that halogen lamps have a short life span, but that is when used in the temperature range shown in the table below where they are normally used. There is no way that a household halogen heater can produce temperatures up to 2000°C. There is indeed no data on whether they are more fragile than other heating elements when heated at the same temperature, but they are unlikely to be fragile.

heater Halogen lamp heater carbon heater
infra-red rays Near (Middle) Equatorial far infrared rays
wavelength 0.78 ~ 3μm 3 ~ 1000μm
temperature range Above 2000°C 1000℃
Warming up speed several seconds several seconds
life span short long

 

manufacturer's lie

First of all, it is often said that "heating equipment that emits far-infrared rays warms the body to the core," but this does not mean that far-infrared rays reach deep into the body. The energy of far-infrared rays is mostly absorbed from the skin surface down to about 200 μm, where it is converted into heat. The heat is only transmitted to the inside of the body through the water in the body.

Next, it is sometimes said that "the fabric is warm because it is woven with ceramics that emit far-infrared radiation." However, as mentioned in the section on heat transfer, heat can only be transferred from a higher temperature to a lower temperature (second law of thermodynamics). If two objects have the same temperature, there is zero heat transfer. Also, thermal energy can move or change form, but the total amount of energy does not increase or decrease (first law of thermodynamics). The reason why you feel warmer when wearing an emergency sheet is not because the sheet is emitting heat, but because the aluminum foil reflects the far-infrared radiation emitted by your body.

Finally, far infrared radiation has no health benefits. As mentioned earlier, every object on earth emits far-infrared radiation, so far-infrared radiation at room temperature is always received.

In conclusion, without needing to compare the electricity costs of different types of heating equipment, air conditioners are the only choice for heating an entire room. The reason is that heat pumps provide more thermal energy than the energy used.

Heat pump is a general term for equipment that transports heat from a lower temperature to a higher temperature. Air conditioners, Eco-Cute (water heaters), refrigerators and freezers use this conversion method.

You might think that this ignores the First Law of Thermodynamics mentioned earlier, which states that the total amount of energy remains the same, but this is not the case. Heat pumps do not create heat; they transfer heat from the outside air in the order shown in the image below. In terms of using something original to the earth, heat pumps that use air heat are also in the same league as solar and wind power generation.


Heat Pumps | Japan Electro Heat Center

 

One problem is that air conditioners are often installed in high locations, so when they are heated, the warm air accumulates near the ceiling and the air around your feet can become cold. In such cases, adding a circulator often improves the situation.

Another thing is that the air may feel drier when the air conditioner is turned on. However, this is not because the amount of water vapor in the space is actually decreasing, but because the room temperature has risen and the upper limit of saturated water vapor has also risen, causing the humidity to drop. In such cases, use a humidifier to adjust the humidity.

At the end of the article, I will post links to recommended circulators and an article on how to choose an air conditioner, if you would like to read it.

 

We mentioned that air conditioners are the most energy efficient for heating an entire room. Electric heaters are also energy efficient when used for partial heating, such as warming people nearby, or when you only want to warm yourself for a short period of time. Therefore, it is not recommended to use an electric heater in combination with an air conditioner, except in situations where you want to warm the entire room while also warming yourself quickly.

However, it is safer not to use electric blankets, hot mats, hot carpets, and other types of heating devices that directly touch the skin because of the risk of low-temperature burns. It is true that low-temperature burns do not occur if they are not used for a long period of time, but they are dangerous because they progress without pain. Children, especially babies, have thin skin, and it is more difficult to control the time if it is not you, so be careful.

Burns caused by prolonged exposure to temperatures between 44°C and 50°C
Low-temperature burns" are burns of a lower temperature than "high-temperature burns," which are caused by contact with hot water or fire. Specifically, it is caused when the skin is in direct contact with an object at a temperature of around 44°C to 50°C for several minutes to several hours. Cases that occur over a period of several hours, such as when sleeping, are common, but if the temperature is close to 50°C, it may occur after only a few minutes of contact. Individuals with thin skin are more susceptible to burns even at low temperatures and for short periods of time.

Slowly progresses deep within the skin, rather than on the skin's surface
Temperatures of around 44°C to 50°C are not painful when touched for a short time, and are rather pleasant when cold. However, prolonged contact will slowly damage the skin without any subjective symptoms.
Although the temperature is low, "low-temperature burns" are by no means minor burns. As with "high-temperature burns," symptoms such as redness and burning, blistering and pain, and dryness and loss of sensation occur as the severity increases. Before you know it, the condition can become so severe that a skin graft is necessary.
Low-temperature burns may not look so bad, but are they safe? Explanation of measures to cope with and prevent low-temperature burns

 

Product Comparison Chart

From the above, we have learned the following

  • As a rule, do not use oil- or gas-fueled heaters
  • Air conditioning is recommended for heating the entire room.
  • Do not use heating devices that come in direct contact with the skin

We will now introduce the recommended electric heaters, but before we do that, let's sort out the different types of electric heaters.

 

In conclusion, there are only two types of electric heaters: carbon heaters and halogen heaters, which are distinguished by their heating elements. Electric heaters are sold under various names, but they all refer to one or both of the above two types.

Let me explain specifically. First of all, regarding ceramic heaters, ceramic is the material that covers the heating element in the first place. As mentioned earlier, the surface of most electric heaters is covered with a ceramic substance. It is complicated because they are sometimes sold independently under the trade name ceramic heater, but most electric heaters are ceramic heaters.

Next, I will discuss quartz tube heaters. To begin with, a quartz tube is a glass tube made from quartz, and a heater in which the heating element is covered with a quartz tube is called a quartz tube heater. However, to begin with, quartz tube heaters are ceramic heaters because ceramic refers to any inorganic material other than metal.

Next, we will discuss graphite heaters. To begin with, carbon refers to all carbon materials, and graphite refers to graphitized carbon materials.

Finally, let me discuss far-infrared heaters. As mentioned earlier, all heating devices (and every object on earth) emit far-infrared radiation, so we believe that far-infrared heaters are a product name to sell to people who have misconceptions about infrared radiation.

 

 

Regarding energy efficiency, since electrical energy is only converted into heat energy, it is not true that only certain electric heaters produce more heat from the same amount of electricity. (First Law of Thermodynamics) In other words, energy efficiency is the same for all electric heaters.

The original concept is the opposite: electric wires, for example, use copper wire with high electrical conductivity, which prevents electricity from escaping as heat. Electric heaters, on the other hand, are designed to dissipate electrical energy as heat energy, so there is no need to think about energy efficiency. However, if the heater is equipped with a fan to blow air or a swivel function, it will also use electricity, making it less energy efficient in this respect.

More than that, using an electric heater, like an oil heater, which should be used only to warm people nearby as partial heating, as heating for the whole room is disadvantageous because the room heats up more slowly and the electricity bill is higher. (The same goes for oil-less heaters, since it's not a matter of just not using oil.)

Carbon heaters and sheathed heaters

Heaters that use carbon as the heating element are carbon heaters, and heaters that use nichrome wire as the heating element are sheath heaters. We cannot find any research on the length of life of these heaters when used at the same temperature as halogen heaters, but we do not believe that their life is particularly longer than that of halogen heaters. However, carbon heaters and sheathed heaters are mainstream products in Japan today and are sold by many manufacturers.

In this blog, we will compare simple models without fan, swivel, humidifier, or air purifier functions for the sake of electrical efficiency. However, we consider it important to have a sensor that detects when towels or laundry are on the electric heater and stops it, so we will compare those with this function.

Manufacturer Yamazen Yamazen Yamazen
model number DBC-SK122 DC-SW092 DS-SD082
Power consumption 1200W / 900W / 300W 900W / 450W 800W / 400W
Dimensions W 330 x D 330 x H 670mm W 280 x D 280 x H 650mm W 305 x D 135 x H 365mm
weight 4.0kg 2.5kg 1.7kg
Price* 10,827 yen 8,682 yen 4,280 yen

*...prices on Amazon as of December 24, 2022.

 

As shown in the table, Yamazen was the only one that met the requirements. Since there are three sizes available, please purchase the product that best suits your room, such as the smallest if you live alone, or the largest if you live in a living room.

 

Halogen heater (halogen lamp heater)

These heaters use tungsten as the heating element. As noted in the table above, it has the fastest start-up time of only a few seconds and warms up quickly.

価格.com found only five manufacturers of heaters sold as halogen heaters. They used to be sold by Hitachi and others, but the boom has passed and they are no longer available. (As mentioned earlier, many people have misconceptions about the lifespan of these heaters, so they are no longer sold.)

Of the five manufacturers, the following two were able to adjust the temperature. No sensors are attached.

Manufacturer TeknTeknos FIFTY
model number PH-803 FL-HA810YD
Power consumption 400 / 800W 400 / 800W
Dimensions W 42.2 x D 32.8 x H 46.4 cm W 42.6 x D 12.5 x H 30.9cm
weight 2.1kg 2.1kg
Price* 6980 yen -

*...prices on Amazon as of December 24, 2022.

 

The FIFTY product was not available on Amazon, but was about the same price as the Technos product on Yahoo and Rakuten. And yet it is compact, so I recommend it.

 

panel heater

As we have mentioned, the type of electric heater depends on the heating element, but the panel heater is not such a distinction, but seems to refer to a low-power, low-profile heater that is placed under a desk in an office to warm feet. I think this one is in demand, so I'll introduce it just in case.

In this blog, we will compare products that have no fan function and can adjust temperature (wattage) just like regular heaters, for the sake of electrical efficiency. (You can scroll to the right.)

Manufacturer Yamazen Top land Iris Oyama Panasonic
item's stock number DP-SB169 SP-PH200 WT PH-TSA DC-PKD4
Power consumption 160W 200W 160W 165W
Dimensions W 40.5 x D 15 x H 32.5 cm (including legs) W 400 x D 36 x H 330mm W 45 x D 30 x H 48 cm 48×45×30cm
weight 1.7kg 1450g 1.7kg 2.2kg
Price* 3,982 yen 4,191 yen 7,480 yen 12,618 yen

*...prices on Amazon as of December 24, 2022.

 

We recommend Yamazen here as well as regular electric heaters, since they have the same features and are the cheapest.

 

I hope you find the above helpful. Please also see here!

blog.enjoy-efficient-life.com

blog.enjoy-efficient-life.com