Re: The American electrical system

>Can you tell if its a three phase facility by counting the number of

>>connections to each cow? ;-) >> >> >> >And which one of the udders is the neutral one? Or is it 2 phase, >neutral and safety >ground?

YMMV but Florida cows are 3 phase wye, grounded through the hooves.

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In message , Jim Ghrist writes


I have an oil-fired boiler (runs on 28-second oil, called 'kerosene' here in the UK) that feeds three heating circuits. Circuit 1 is downstairs radiators, circuit 2 is upstairs radiators, circuit 3 is domestic hot water. The three circuits are independent and are switched by an electromechanical control valve in each circuit. The hot water is produced in an indirect cylinder, a copper cylinder containing a copper tube spiral. The spiral is connected to the boiler where hot water at about 70 centigrade (160 Fahrenheit) is recirculated and the hot water for cleaning, washing, bathing etc. is drawn from the cylinder at about

60 centigrade (140 Fahrenheit). The cylinder volume is approximately 160 litres or 35 Imperial gallons (38 and a half US gallons). The boiler fires maybe once every three hours for five minutes or so to keep the water at usable temperature (more often, of course, if any hot water is being used). The upstairs and downstairs heating circuits are just switched off during summer.

This system, using oil or gas (methane, not petroleum spirit :-)), is actually quite common in the UK. Thermal efficiencies in the high 90 percent range can be reached with the right boiler. Even my old Mistral unit is probably over 80% thermally efficient.

I have a 3KW electrical "immersion heater" in the copper cylinder for emergency standby purposes (boiler failure or running out of oil).

My oil costs me about 30 cents US a litre on a bad day and as little as

15 cents on a good day. Kerosene has an energy content of 43 MJ/Kg and a kilo of oil is around one and a half litres, at a cost to me of somewhere between 22 and 45 cents (let's say 43 cents, keeps the arithmetic easy). That's 1 cent per MJ. My utility company charge me about 10 cents per KWh for electricity. That works out at 3.6 MJ, so that's roughly 3 cents per MJ. Even with thermal losses, burning oil at home is twice as cost effective for me as burning electricity from the public utility.
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Peter Scales

In message , Jim Ghrist writes

Not really, trust me :-) Biggest problem I have is bearing failure on the blower/oil pump assembly (and paying for 600 gallons of fuel at a time...).

The oil boiler is about the same level of complexity as the gas furnace you refer to (my mother runs a gas furnace) but our natural gas prices do not beat our kerosene prices in the UK Joule for Joule.



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Peter Scales

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