Voltage Optimisation Hard Sell

[Onoff]

Had a visit from my unfortunate mate at the weekend. When I say unfortunate perhaps gullible is a bettter term.

 

If you knock on his door or ring him up he'll buy "it".  Wills, funeral plans, pc support contract, double glazing (already had it!). Just sound clever and he'll write you a cheque and never get a second or third quote. He's bought a hot tub off you? Get him to pay cash and tell him he has to supply and run the armoured! Etc, etc. Probably easier just to ring him and say you're the bank running a security check and could you have his PIN, 3 digit code etc (twice that's happened).

 

I try and protect him and steer him right but he's so bloddy nice he says yes THEN phones me to say what he's done.

 

An early adopter of PV he's since been sold "batteries" by an affiliated company (still waiting to get photos of them, apparently sat on carpet tiles in the loft). The latest is he "has a bloke coming round...who rang up...they fit a box...the Government wants everyone to have one by 2020...get in early to beat the rush"...".

 

More snake oil!

[Jeremy Harris]

Snake oil indeed.  I think we've discussed these before, but the fact they cannot defeat the laws of physics, despite claims that come very close to stating that they can, seems to escape a lot of people.  Most electricity ends up heating something in a house, hot water in a dishwasher or washing machine, compressed refrigerant in a fridge freezer, domestic hot water in a cylinder or a kettle to make a cup of tea.  There's a fixed equation that determines how much energy is needed to do this, and decreasing the voltage (which is what these things do) just increases the time taken, and that actually increases the electricity used, because the losses are higher.

 

Take a kettle with 1 litre of water in it at room temperature, 20 deg C.  To heat it to 100 deg C will take a fixed amount of energy, ignoring losses.  That energy is pretty straightforward to work out, it's the specific heat of water x the volume x the temperature change, so in this case 1.161389 Wh/K/l x 1l x (100 deg C - 20 deg C) = 92.9 Wh. 

 

If the kettle element is rated at 2 kW at 230 VAC, then at an electricity supply voltage is 240 VAC the kettle element will deliver about 2.091 kW (2091 W).  The boiling time is the energy required / power (ignoring case and evaporation losses for the moment), so will be 92.9 Wh / 20191 W = 0.046 hours = 2.76 minutes.

 

If the supply voltage is then "optimised" to 220 VAC, the kettle element power reduces to 1.91 kW, so the time taken to boil 1 litre of water from 20 deg C to 100 deg C (again, ignoring losses) = 92.9 Wh / 1910 W = 0.0486 hours = 2.92 minutes.

 

So, the kettle takes longer to boil with the "optimiser", but uses the same basic power to boil the water (so no energy saving).  BUT because it takes longer to boil the heat losses from the kettle case and the evaporative heat losses will increase.  At a conservative estimate, the kettle boiled with a voltage optimiser fitted will use around 5% MORE electricity than one without.  The same goes for every single appliance that heats something, be it a domestic iron, or the compressor in a refrigerator, as well as all the water heating elements found in things like washing machines etc.

 

How these rogues get away with sort of con trick is beyond me.  I would have thought that they must be coming very close to breaching the advertising regulations.

Edited September 4, 2017 by JSHarris