Help with energy monitor

SnowWhiterThanWhite

Have just received my free British Gas energy monitor & have set it up over the weekend.

I have been 'testing' the readings by switching various appliances on/off.

The one thing I don't understand is, when I switched on the oven, the reading went from around 500w to 3KW, but, after around 10 minutes when I checked again, the reading had come back down to around 900w. The same thing has happened with the kettle, and the iron?

Does this sound right? I assumed that appliances would use the same level of electricity whilst they are on, or, do they fluctuate once they get to a certain temperature?

Thanks

Premier_2

After 10 minutes, I would have hoped the kettle would have boiled the water and so cut out.

The iron and oven would do similar ( althogh the oven may take longer than 10 mins to heat up to the set temperature) Unlike a kettle, both will then cut back in and 'cycle', so maintaining the desired temperature.

SnowWhiterThanWhite

That makes sense! Thanks

Geoff_W

Is it the BG Minim, ie the one with the 'speedometer' type readout?

penrhyn

When an appliance reaches the desired temperature the power is cut off by a device called a thermostat. In the olden days a bimetal strip was used, when heated one side expanded more than the other causing the strip to bend. This either made or broke the electrical connection, these days solid state electronics are used.
Have they stopped doing physics at school?

Premier_2

penrhyn wrote: »

...Have they stopped doing physics at school?

Yep, in over 50% of our state schools, (100% in certain geographic areas) separate science gcse's are no longer taught. As they are seen as a pre-requisite to studying A levels in those subjects, it's not surprising the current dearth of students wishing to pursue their study at University in this and related disciplines.

http://www.guardian.co.uk/education/2009/jun/03/science-gcses-state-schools

Got a glimpse of my old physics labs in my former school the other day (now just science or combined science is taught there). I was horrified. None of the traditional range of apparatus, no bunson burners or gas taps, no electrical power points on the desks ... in fact just a load of basic tables and chairs in an otherwise essentially empty and uninspiring room with an expensive looking large computer screen at the front (where a blackboard would have traditionally been) where everything appears to be taught via.

Without the practical, engaging content that presumably interested those in the past that studied the individual sciences, it's no wonder no one is interested in learning these essential science disciplines today (even if there was anyone/where that taught them)

Geoff_W

penrhyn wrote: »

Have they stopped doing physics at school?

Probably. Schools don't teach children how things work anymore, it's all about passing exams.

The trouble with energy monitors is that they make a big thing of the instantaneous reading. Put the kettle on and, OMG! I'm running up a bill of £000's a day/month/year. But when the water has boiled, phew! it's back to normal again. The fridge and freezer have another short-term effect. When they switch on you may see an immediate spike of several hundred Watts, but it soon settles back to a more reasonable figure. But even this is misleading, because a fridge or freezer is not running its compressor all the time, so the consumption is nowhere near as high as initially indicated.

Any appliance which operates intermittently, such as a fridge, freezer, immersion heater, washing machine etc., is impossible for an energy monitor to give an accurate instantaneous reading - it's either displaying lots of Watts, or none.

Personally, I have found the clip-on-the-meter type of monitor to be fairly inaccurate. Check them against the meter over several weeks to see by how much. Plug-in types seem much more accurate but can only monitor one appliance at a time (not easy with a wired-in cooker, though!) but at least they can measure long-term consumption.

I suggest the OP uses their monitor to try to minimise the 'background' usage. You would be amazed at how much electricity is wasted by all your 'stuff'. The trick is to find out how low you can get the monitor to go. Get the kids (or grandkids) involved in this new, exciting game of 'The Disappearing Watts'. Find the hidden, nasty wall-wart that is thwarting all your attempts at a zero-Watt game winner!

penrhyn

Neddy Seagoon:What? What? What?

Grytpype-Thynne: Only three watts, you're not very bright tonight Neddy!


Goon Show 1950's

Geoff_W

He's fallen in the water!!!!

Showing our age now, aren't we?

Cardew

penrhyn wrote: »

When an appliance reaches the desired temperature the power is cut off by a device called a thermostat. In the olden days a bimetal strip was used, when heated one side expanded more than the other causing the strip to bend. This either made or broke the electrical connection, these days solid state electronics are used.
Have they stopped doing physics at school?

If the electronics are solid state, how does it bend;)