Rooftop Solar Panels

[wim121]

Tricky with subsidies involved that even make solar voltaics look competitive, assuming the subsidies last. Not sure if heat pumps are included in subsidies currently, and if not why not? David MacKay is a fan, and is advisor to the Department of Energy and Climate Change, so if not subsidised currently things may change on that front. And dump the solar voltaic subsidy, which is just a big wheeze for chancers.
Ch 21 Page 146: Sustainable Energy - without the hot air | David MacKay

1 watt of electrical energy in, 4 watts of heat energy out. Can't be bad. Seems DIYable too.

So working out all the radiators in my house, going full pelt in winter (because I like to walk around nude), averaging 30,000btu's per rad, I calculate for all rads going full whack that would be 270,000btu's, which converted is 80watts.

So that would mean I would need 20watts of electrical energy to run it? So to use 1kwh (14p per kwh on my tariff) going offthose figures, running at 20watts continously would be 50hrs, just over two days? So in one month, it would be around the £2 mark for heating?

Sheesh, if those figures are correct, then even with a new-ish gas installation, Im spending over £50 per month on heating and hot water, the majority of that money on heating. If those figures are right I could save £576 per year?

[TimberWolf]

So working out all the radiators in my house, going full pelt in winter (because I like to walk around nude), averaging 30,000btu's per rad, I calculate for all rads going full whack that would be 270,000btu's, which converted is 80watts.

So that would mean I would need 20watts of electrical energy to run it? So to use 1kwh (14p per kwh on my tariff) going offthose figures, running at 20watts continously would be 50hrs, just over two days? So in one month, it would be around the £2 mark for heating?

Sheesh, if those figures are correct, then even with a new-ish gas installation, Im spending over £50 per month on heating and hot water, the majority of that money on heating. If those figures are right I could save £576 per year?

All your radiators going full pelt will be using more than 80 watts (two light bulbs worth). Might be easier not to use BTUs and stick with modern units (kWh's). Not sure of the savings in practise. As David MacKay says, it's surprising heat pumps are not more utilised in the UK. There must be a fly in the ointment somewhere.

Like district heating and combined heat and power, heat pumps are already widely used in continental Europe, but strangely rare in Britain.
Ch 21 Page 146: Sustainable Energy - without the hot air | David MacKay

[wim121]

All your radiators going full pelt will be using more than 80 watts (two light bulbs worth). Might be easier not to use BTUs and stick with modern units (kWh's). Not sure of the savings in practise. As David MacKay says, it's surprising heat pumps are not more utilised in the UK. There must be a fly in the ointment somewhere.

What calculation would you use to get from btu's to watts output of a rad? Am I calculating it wrong?

Im converting from btu's as all my rad max outputs are measured in btu's and plumbers use btu's to calculate rad sizes needed to heat a room ....

[wim121]

Two blades flew off

'T HE eco-dream of a village school turned into a Friday 13th nightmare when high winds destroyed their wind turbine.
Two blades flew off from the 15m tall turbine in Gorran School’s playing field during the bad weather earlier this month. The turbine was part of the school’s £53,000 plan to generate its own electricity'

While I would be willing to exploit wind and use it as a power source, I hate it as it is one of the most environmentally harmful and inefficient forms or energy and far from renewable.

People dont realise the raw materials that go in to the construction and maintenance of them as well as the harm they cause to their surroundings. Dreadful things! But if I can make money off the grid by producing energy, it's worth considering.

Surprisingly, the greenest form of energy is nuclear power. Methane also shows great potential ....

[wim121]

All your radiators going full pelt will be using more than 80 watts (two light bulbs worth). Might be easier not to use BTUs and stick with modern units (kWh's). Not sure of the savings in practise. As David MacKay says, it's surprising heat pumps are not more utilised in the UK. There must be a fly in the ointment somewhere.

What calculation would you use to get from btu's to watts output of a rad? Am I calculating it wrong?

Im converting from btu's as all my rad max outputs are measured in btu's and plumbers use btu's to calculate rad sizes needed to heat a room ....

Oooops, looking back over, is 270,000 btu's approx 80 kwh/hrs?

If so, I forgot to move the decimal point at my previous calculation.

If that calculation is correct, it means it would cost £11.20 an hour? That cant be correct can it?



Gahhh, my mathematics is failing me ....

[TimberWolf]

Oooops, looking back over, is 270,000 btu's approx 80 kwh/hrs?

If so, I forgot to move the decimal point at my previous calculation.

If that calculation is correct, it means it would cost £11.20 an hour? That cant be correct can it?



Gahhh, my mathematics is failing me ....

Yes, 80 kWh. Let Google convert it. (Jeez, that's a big URL in uncompressed form!)

I thought my gas bills used to be in kWh's (1 unit = 1 kWh), but maybe yours is still BTUs. 1 kWh is a 1 bar electric heater going for one hour. So I guess a radiator is about that ballpark? And on the gas bill there would be the price per unit. If not, you've some conversions to do, not fun.

[TimberWolf]

Oooops, looking back over, is 270,000 btu's approx 80 kwh/hrs?

If so, I forgot to move the decimal point at my previous calculation.

If that calculation is correct, it means it would cost £11.20 an hour? That cant be correct can it?



Gahhh, my mathematics is failing me ....

80 kW would be a heck of a lot of heating (80 1 bar electric heaters!). Not sure where your figures are coming from. BTU is an amount of energy (like Joules), rather than an amount of energy used per time (watts). What period is that 270,000 btu's (an amount of energy, not power) over?

[Troll]

Just put bypass circuits between the supply and meter for your gas & leccy

HTH

[TimberWolf]

Anyway, my guess would be if you've already got an efficient boiler it wouldn't make sense to buy a heat pump. These are probably more suited to people who are putting in a new heating system. Especially if they were going to use electric heating.

[wim121]

Yes, 80 kWh. Let Google convert it. (Jeez, that's a big URL in uncompressed form!)

I thought my gas bills used to be in kWh's (1 unit = 1 kWh), but maybe yours is still BTUs. 1 kWh is a 1 bar electric heater going for one hour. So I guess a radiator is about that ballpark? And on the gas bill there would be the price per unit. If not, you've some conversions to do, not fun.

80 kW would be a heck of a lot of heating (80 1 bar electric heaters!). Not sure where your figures are coming from. BTU is an amount of energy (like Joules), rather than an amount of energy used per time (watts). What period is that 270,000 btu's (an amount of energy, not power) over?

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.