Rooftop Solar Panels

[TimberWolf]

No, my gas meter is in cubic feet (old style meter), so I multiply my reading by 1.226 or whatever, to get kw/hrs. If I spend £50 one month, for example, on 4p per unit for gas, that is 1250 units per month, or 42kwh per day roughly .....

Im not just talking about the amount of energy I use to heat my water though.

When speaking about btu's Im speaking about the rating for each radiator, on the maximum amount of heat it is capable of putting out. You can take the area of a room and calculate the btu's needed for that room. Then when purchasing a radiator, you can select the right size, type, design, etc and make sure you're not under or overheating a room. When you buy a radiator, it will have the btu rating, so you know how much heat it will throw out.

So I would presume the bigger the radiator and the more it disperses heat at a better rate and more pipework, the more liquid in your system to heat, hence higher energy bills. Maybe Im not applying the calculation for heating the water though correctly as both costing figures I worked out above seem a little unbelievable.

Ah, the joys of ancient units. Feet too, marvellous.

It turns out BTUs are short for BTUs per hour. This kind of omission is quite normal with ancient units.

Anyway the conversion from BTUs (per hour) to Watts is BTU * 1055 Joules / 3600 seconds, or about 0.2931 *BTUs

So your 30,000 BTU capacity figure for each radiator is 8.8 kilowatts. 9 electric fire bars. Seems about right at full pelt.

And your 270,000 BTU figure is 79 kilowatts.

Forgotten why you needed this now.