Central Heating - Expert Assistance Required

But the temperature differential is determined by the size of the radiators and the flow rate and not by the boiler. I still don't see why there is a difference between the two types.

Increaseing the temperature difference reduces the efficency of the radiators. (The top would be at 80C the bottom 60C assuming no losses in the pipework (insulation).)

Incidently mine runs at 85C flow and 75C return but its sized to maintain temps down to -15C not -1C like most are.

Don't do this with normal radiators they will burn at that temperature. (Skirting heating works well at that temperature.)

I think you will find that is the reason they use mixing valves and low tempreture flows in business. It is better to have large radiators at 60C than be sued by running them at

No it took fuel, and released the potential energy from it.

I think you will find that "heat" is energy as far as anything (or one) is concerned.

No, power does not come into it. power is a measure of the rate of doing work. It is not until you use the energy that you can ascertain the two bits of information you need: How much energy was used (i.e. the amount of work done), and how long did it take. Then you can calculate "power"

All the "power station" is doing (viewed as a black box) is changing energy from one form to another.

You forget that these are plastic pipes connected with the revolutionary copper free brass compression fittings referred to by Dribble the other day. :-)

On Planet Zog the impossible happens all the time and normal earth physics are a thing of the past. For example combi boilers actually manage to fill a bath with lukewarm water before the boiler needs another annual service.

No, not at all. The radiator has to be sized for that room though at 80 -

Nothing at to do with suing. It is to do with efficiency. Scandinavian countries have had 60-40C for many years.

Yes, just for you.

It is?

So, it's not wrong.

It is because we buy out electrical energy using that.

Get your money back.

So energy. A tank of diesel is a tank of energy.

Yep.

It does come into it. A tank of diesel to intents is a tank of energy. It is used to create power which charge the energy from one state (oil) to another heat. It took power to do the state change.

And uses power to do it. So, power comes into the reckoning.

A boiler: The output is in "power". Yet the boiler just converts one energy state (oil) into another (heat). Yet the output is rated in "power". It takes power to do the state conversion.

Oh no we don't! We buy it in kilowatt-hours - not kilowatts *per* hour.

I can't - it was so long ago that the state paid!

But even though I've forgotten a lot, I can still remember more Physics than you'll ever know!

Yet another travesty of the facts! The power rating of a boiler is simply the *rate* at which it can convert the energy in the gas or oil into heat and impart it to the circulating water. This is measured in energy per unit time - whether it be BTU per hour or kilo-joules per second (better known as kW).

The only power used to do the conversion is that due to the *inefficiency* of the process - so if a boiler is (say) 90% efficient, 10% of the energy in the fuel ends up heating the neighbourhood or whatever rather than your house!

It is clear you forgot a hell of a lot. Alas I know all about life and everything therein, and answer is not 42.

It is?

So, power in there somewhere.

Which is time.

Power = Energy x Time. So this energy and the rate (time) sounds like power.

Which is power.

Power again.

So, this power is used to change one energy state to another then. Which is what I said.

I fear taxpayers money was wasted.

I'm afraid Set Square's description was entirely correct except that in his last paragraph he said "The only power used..." when he meant "The only energy used..." (which was about the only thing you didn't query). In a previous post you claimed the power station "burned energy to make power". One can neither "burn energy" (only convert it from one form to another) nor "make power" (as it's a rate, ie so much of something per second). One can convert energy at a certain rate (which is power). In a 100% efficient boiler (using the commonly accepted definition rather than the manufacturer's one) all the converted energy gets out into the water by heating it up. Some energy is lost to the atmosphere however and the rate at which it is lost compared with the rate it gets into the water gives one the inefficiency. The use of the terms "power station" and "power supply" are rather looser terms generated by the need to satisfy consmer "power requirements" (ie the rate at which they wish to use energy).

You are falling into the trap of using "power" in a colloquial sense. Power is not something you can consume in a strict sense. You can use energy (you don't even consume that - just change its form), but you don't use power - it is simply a measurement of the rate of energy use.

No. In absolute terms no energy is gained or lost in the reaction.

What he was saying was that energy in - energy out = the energy used to create power to do the state conversion of one energy state to another.

Overall what he was trying to say was what I wrote to totally wrong, yet what he wrote agreed with it except for the point you picked up, which was right except it was poorly written.

Well burnt fuel which contains energy (CV)

Which is what I have been saying.

energy x time = power. The speed of consuming energy.

yep.

yep.

yep. The term "power" station is a misnomer.

Power: Strength or force exerted or capable of being exerted, produced by "energy". The rate at which work is done, expressed as the amount of work per unit time and commonly measured in units such as the watt and horsepower.

Power and Energy are interchanged liberally and confuse. It is easy to see why. As power is a result of energy x time. So to get energy you divide the power by time. We pay for electricity in skewed way as a unit (energy) is power x time.

Power is a result of energy.

Yep.

So all boilers are 100% efficient then. That is nice to know.

Makes as much sense as "speed is a result of distance"...

Indeed they are:

A - B - C - D - E - F - G = 0

A = Energy in B = energy imparted to water C = energy vented to flue D = energy used to provide latent heat of vaporisation to water created in the gas / oxygen reaction E = energy lost to room F = energy converted to acoustic noise G = all other energy components not accounted for in B through F above

Alas you are only usually only interested in B and some of D

It doesn't as Enery x Time results in Power.

No.