Electric Induction Hob

A few weeks ago, I treated myself to an electric induction hob, the Tefal 1H Everyday. I’ve yet to figure out how to change a gas bottle and as I’m currently on a shoreline, I decided to take advantage of the essentially limitless electricity rather than have the hassle of lugging around heavy steel cylinders. The hob itself runs on 240v and uses a magnetic induction field (doesn’t that sound all Star Trek-y?) to generate heat in the bottom of the pan resting on top of it. The hob itself doesn’t heat up, it simply heats the pan up, which makes it more efficient than a traditional electric hob. These rely on friction to heat an element, which is then used to heat the pan, friction that is caused by putting too much current through a wire. Too much current going through a wire is also how a lot of fires get started. The magnetic field is created in a circle underneath the pan, which introduces eddy currents in the metal of the pan itself. This causes the pan to heat up, rather than the hob.

One of the downsides to using an induction hob is the necessity of having a pan that is compatible. An easy way to test for compatibility is to put your fishing magnet on the bottom of the pan- if it sticks, the pan will work. I paid £7 for a suitable pan from my local bargain store, so buying a specific pan to use shouldn’t prove too expensive.

During testing, wherein I boiled one litre of water in the 3000W kettle and another litre of water in a pan on the hob set to 2100W, the kettle boiled the water nearly a minute faster at 2m32s, rather than 3m28s. However, the kettle is significantly more powerful than the hob.

Some of the upsides are as follows:

  • The hob itself cost less than £40 and it can be used quite economically. The technology itself is more efficient than old-fashioned “spiral” rings, but the hob can also be set to use a specific wattage – mine will vary between 450W and 2100W with seven steps in between.
  • The model I have will work on a modified sine wave inverter. My current inverter is rated to 1200W, which means I can use any of the four lowest settings – 450W, 600W, 850W and 1000W.
  • It’s easy to set the amount of watts used, as the manual power settings correspond to a given amount of energy.
  • The unit is small and portable. It’s less than 4″ high, which means it can be stored in the bottom of a cupboard and taken out when needed for use.
  • 450W (P1) is sufficient for simmering, but the induction field is switched on and off which may prove problematic for some foods. I’ve never had a need to take it past 1000W (P4). The LED screen shows you exactly what is going on.
  • I’ve been able to run the hob and my 1300W halogen oven simultaneously without causing a problem with the shoreline, by keeping the power usage of the hob low.
  • The timer feature of the hob can be quite useful. For example, I can simmer rice for 15 minutes and then check on it when the timer beeps. It will also turn the hob off after those 15 minutes, which means that noting is burned onto the pan. An hour’s simmering will draw less than 38 amps from the batteries.
  • It’s very easy to clean. The hob surface is a shiny black material that is easily wiped over with a cloth.

Overall, I’m quite pleased with my purchase. It’s compact, runs from the inverter, can be set to specific times and energy uses and is portable. The only change I’d make next time I purchased one would be to buy a model that has two hobs rather than just one.


June 2016 Boat Audit

Over the month of May, I filled the water tank twice, spent £15 on fuel (mostly firelogs), emptied the Thetford once and used 39kWh of electricity from the shoreline. I’ve burned a few firelogs, but mainly for comfort rather than necessity.

I’m starting June with:

  • 0.4 of a water tank, according to the gauge,
  • A notation of 18880kWh on the electricity meter,
  • A 1/3rd full Thetford. I’d love to be able to go a full month without emptying, just to keep things neat, but I don’t think that’s really practical.

In which I talk about toilets.

Every boater’s favourite subject.

Wait, don’t go. You know you want to know how I managed to go three weeks without emptying a Thetford cassette, despite daily use. Don’t you?

Emptying a cassette toilet has to be up there in the top few manky jobs that have to be done on a boat, along with emptying the bilge. I’m not especially tittle-stomached, but the smells and sounds that come from the sluice when performing the necessary duties turn my head. I also dislike the idea of having to cruise to an elsan point every few days and having to pay money for Blue/Green. So I came up with the idea, based on a little research, of separating solids and liquids. I will be discussing solids and liquids in this post, so if you’re squicked by such things, please don’t read any further. You are going to learn some things that perhaps you don’t want to know.

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“Doesn’t it get cold in Winter?” – Part I

If you’ve ever told anyone that you live on a boat, you’ll have heard this question, I’m sure.

Keeping warm on a narrowboat is actually relatively easy. There are several ways to heat the inside, some of which are more expensive/simpler than others, and also several ways to keep the heat in once you’ve added it.

In my own personal opinion, insulation is by far the most important thing. There are two main kinds – polystyrene and spray foam. Polystyrene is cheap, lightweight and easy to handle, even for a layperson. It’s also easy for it to fail, creating a heat gap that can cause condensation. This is often a death knell for a wooden-cabined boat and won’t do a steel boat any favours either. Spray foam is much more difficult to work with and often more expensive, but is a far superior product. Due to the fact it expands as it cures, it will fill any small crevice it is applied to and when applied properly, will create a solid “tube” of insulation, leaving nowhere for heat to escape.

Speaking in very general terms, there are three kinds of heat: conduction, convection and radiation. In terms of physics, there are several others, but we’re only going to concern ourselves with these three. Heat is transmitted conductively by touch, such as wrapping your hands round a hot mug of cocoa on a cold day or burning your hand on a hot stove. Heat is transmitted convectively by air, such as the gust you feel wafting into your face when you open a hot oven, or conversely, the cold draught you feel on your feet when you leave the fridge door open (in terms of physics, there is no such thing as “cold”, just more or less heat energy). Heat is transmitted by radiation through infrared radiation, which is the kind of heat you feel when standing near a wood burning stove, unless you have a stove fan or are laying on top of the stove which would be convective or conductive, respectively. It’s also the kind used in this huge patio heaters you often see in pub beer gardens. In terms of transmissible distance, conduction is the shortest while convection is the longest, which is why you need to be near a stove to get the benefit from it.

Water and metal are very good conductors. That is to say, they both transfer heat energy well, while air is a poor conductor. Heat will always flow from a hot thing to a cold thing, not vice versa (see entropy, and the second law of thermodynamics). Imagine a room with a temperature of 20°C and a cup of air and a cup of water on a table. Both the air and water are at room temperature – 20°C – yet a human (with a body temperature of 37°C) will perceive the cup of water as being colder than the cup of air. This is because heat energy will be drawn much more quickly from the body by the water than by the air. Another example would be touching your bare hand to a metal car body on a frosty morning – both the car and air are the same temperature, but the metal car is much more efficient at transmitting heat energy, conductively in this instance, than the air is.

With regards to narrowboats, they are generally made of steel (a good conductor) floating in water (another good conductor). This is why it is essential to ensure that one’s insulation is up to snuff – without sufficient insulation, the entirety of a narrowboat will become the same temperature as the water it’s floating in. Without insulation, far greater quantities of heat energy would be necessary to maintain a comfortable temperature inside the boat, as anyone who has seen their heating bill when someone has left the door open will attest. Add in the relevant vents to provide fresh air for the stove, the often single glazing and the lack of thermal mass, and the answer to the question is “Well, it certainly can get cold in Winter,”.

May 2016 boat audit

I’ve decided to keep track of my usage of things like water, electricity, etc, on the boat. To that end, and because today is the first of a new month, I filled the water tank, emptied the toilet cassette and counted how much fuel I have.

I started this morning with the following things:

  • 2x full bags of Homefire coal.
  • 1x partial bag of house coal
  • 1x full box and 1x partial box of Zip firelighters
  • 1x partial bag of Poundland “Magic” kindling – essentially some strips of wood dipped in wax which remove the need for firelighters.
  • 2x Poundland firelogs.
  • A full water tank.
  • An empty toilet cassette, though I am attempting the separation of solids and liquids where practical.
  • A notation of 18841 kWh on the shoreline electricity meter.

I’m going to keep track during the month of what I spend/use, and update this accordingly.

  • 2nd May: 1x bag of normal kindling from Poundland – £1.
  • 7th May: 3x firelogs from £1 shop – £3.
  • 14th May: filled the water tank to overflowing.
  • 20th May: 5x firelogs from Wilko – £5, 1x bag of Homefire heat logs – £4.
  • 24th May: 2x firelogs from Poundland – £2.

Additionally, I’ve foraged several logs to use for kindling.

Filled the water tank on 14th, and again on 24th. Using the washing machine puts a big dent in the amount of water in the tank.

Emptied the cassette on 24th. Twent four days usage from a single 21L tank. Separating the liquids has been a very good idea.