Heat yourself, not entire house

Cardew

Empty_pockets wrote: »

Hmm, don't know tat much about boilers but still a little confused.

I would guess it's the hot water dissipates the heat and it circulates round the system.
Does the water then return to the boiler to be heated to a certain temprature again?

I always figured a boiler burner lit for 1 hour, servicing 1 radiator would use the same gas as a boiler burner lit for one hour, servicing 5. I've seen it lit and it seems to be a case of on or off, the flame isn't regulated depending on flow rate as far as i can see. the only adjustment i have on mine is temprature setting for water outputs for both tap and radiatiors.

Should clarify - the 'central' heating is on, regardless of how many radiators it's servicing.

Yes you are correct that each radiator dissipates the heat. So if you have two radiators of the same size, they dissipate twice the the amount of heat. When a radiator is switched off, no hot water is passing through the radiator.

The water from the radiators does indeed return to the boiler and is re-heated. So if the capacity of a radiator is say 10 litres, your boiler is is heating that amount(10 litres) and the radiator(and pipes) are dissipating that heat.

If you have 5 radiators switched on, the boiler is heating 50 litres of water and all 5 radiators are cooling that water by dissipating the heat.

Your boiler does 'modulate' its output(i.e. turns down the flame) much like on a gas stove you will turn down the level of heat. A boiler output might range from, say, 8kW to 30kW. So if the water circulating round the central heating system is all at the same temperature(that you have set on the boiler control), the boiler cannot go lower than giving 8kW so will stop firing.

If you can't see the flame reducing, it could be that the boiler is then heating the water in the Hot Water tank(assuming the boiler is not a combi)

Cardew

grahamc2003 wrote: »

Looks like you've got your work cut out today Cardew!


LT - Nope, you have it completely wrong in both posts as I'm sure Cardew will patiently explain (for about the millionth time!).

I suspect it would be just wasted effort!

londonTiger

Cardew wrote: »

So to keep a room at the same temperature four 100 watt light bulbs will keep it as warm as a 400 watt halogen heater or a 400 watt oil filled radiator and use the same energy.

So I guess my 400w halogen heater will create the exact same light as four 100w light bulbs too... This room Im sitting in must be very very bright right now... but oh.. look at this, something must be wrong, because it's barely giving off a dim orange light that I would struggle to read a book with.

You're not going to reply because you made a dumb half assed comment and you cant back it up

cajef

londonTiger wrote: »

You're not going to reply because you made a dumb half assed comment and you cant back it up

It is you that is being dumb assed, we are talking about heat not light, as Cardew stated four one hundred watt bulbs will give out exactly the same amount of heat as one 400 watt heater, it is the laws of physics.

SYNERGY

Empty_pockets wrote: »

Hmm, don't know tat much about boilers but still a little confused.

I would guess it's the hot water dissipates the heat and it circulates round the system.

Yes you are correct, the boiler heats the water, the water gives up the heat to the room as it passes through the radiators and pipework.

Does the water then return to the boiler to be heated to a certain temprature again?

Correct again, the water will potentially be heated to the maximum temperature set on the boiler temperature setting.

I always figured a boiler burner lit for 1 hour, servicing 1 radiator would use the same gas as a boiler burner lit for one hour, servicing 5. I've seen it lit and it seems to be a case of on or off, the flame isn't regulated depending on flow rate as far as i can see. the only adjustment i have on mine is temprature setting for water outputs for both tap and radiatiors.

I'll describe a very simple system.

You have a boiler, radiators, boiler thermostat and presumably a room mounted thermostat. (To simplify things we'll presume the radiators do not have TVR's. nor is there a programmer or timer).

You have a house with four rooms, each room loses 1kw of heat per hour, so the boiler and radiator in the room has to provide 1kw per hour per room to keep the temperature stable.

If only one radiator is on the boiler will only need to produce 1kw per hour.

If four radiators are on the boiler will need to produce 4kw per hour.

So if gas costs £1 per kw, using one radiator would cost you £1per hour.

Using four would cost you £4 per hour.

When you say "I've seen it lit and it seems to be a case of on or off, the flame isn't regulated depending on flow rate as far as i can see." it can be misleading, though the boiler has to provide, in our example 4kw per hour, the boiler at maximum may be able to provide 10kw per hour.

When fired up initially the burner may in fact be producing 10kw per hour, however this will vary in one of several of ways (depending on boiler and controls).

1) If the maximum set boiler temperature is reached it, the burner will be extinguished until it reaches a preset lower temp, the burner will then fire up again

2) If the 'roomstat' temperature has been reached again the burner will be extinguished, firing up when the room temperature drops and the 'roomstat' calls for heat.

3) The boiler may be a 'modulating' boiler, what this simply does is vary the gas flow to the burner, and heat to the water, depending on various parameters, in some boilers you can observe this happening, it is possible to observe the height of the flames vary slightly at the burner.

So though we need to provide 4kw per hour and the boiler can produce 10kw per hour, due to the actions of 1,2 and 3 the average output from the boiler will be 4kw per hour ie the boiler burner won't be operating continuously for the full hour.

Should clarify - the 'central' heating is on, regardless of how many radiators it's servicing.

As I mentioned at the beginning, I have described a simple system and used simple figures for clarity.

Hope it gives you a bit of an insight into what happens in that white box on the wall.;)

Cardew

londonTiger wrote: »

So I guess my 400w halogen heater will create the exact same light as four 100w light bulbs too... This room Im sitting in must be very very bright right now... but oh.. look at this, something must be wrong, because it's barely giving off a dim orange light that I would struggle to read a book with.

You're not going to reply because you made a dumb half assed comment and you cant back it up

It seems to me you cannot read, or if you can read, you are incapable of understanding what you have read.

Do you not get embarrassed by displaying both your ignorance and rudeness in a single post?

SYNERGY

londonTiger wrote: »

So I guess my 400w halogen heater will create the exact same light as four 100w light bulbs too... This room Im sitting in must be very very bright right now... but oh.. look at this, something must be wrong, because it's barely giving off a dim orange light that I would struggle to read a book with.

You're not going to reply because you made a dumb half assed comment and you cant back it up

So I guess my 400w halogen heater will create the exact same light as four 100w light bulbs too..

I think you are getting mixed up a little.

You are comparing a heater with light bulbs.

1x400w halogen heater will produce exactly the same heat as 4x100w bulbs.

However 1x400 halogen heater won't produce the same quantity of light, measured in lumens, candela, footcandle or lux (take your pick for light measurement) as 4x100w light bulbs.

Empty_pockets

Cheers for the info.

I feel warm and enlightened!

ladylouise62

SYNERGY wrote: »

So I guess my 400w halogen heater will create the exact same light as four 100w light bulbs too..

I think you are getting mixed up a little.

You are comparing a heater with light bulbs.

1x400w halogen heater will produce exactly the same heat as 4x100w bulbs.

However 1x400 halogen heater won't produce the same quantity of light, measured in lumens, candela, footcandle or lux (take your pick for light measurement) as 4x100w light bulbs.

OK, a non-physics-expert question - are they not using the same amount of energy (I thought that the wattage would describe the amount of energy)?
If they are, then with both producing the same amount of heat, but one also producing more light, where does the energy not put into the extra light go in the Halogen?

This is a serious question, I really want to know.

Derivative

ladylouise62 wrote: »

OK, a non-physics-expert question - are they not using the same amount of energy (I thought that the wattage would describe the amount of energy)?
If they are, then with both producing the same amount of heat, but one also producing more light, where does the energy not put into the extra light go in the Halogen?

This is a serious question, I really want to know.

The halogen heater will directly* produce more heat than four incandescent bulbs.

In addition, a light bulb will generally be located such that heat is directed into other rooms. A heater placed lower in a room has a better chance of heating the surrounding air.

We really don't need any study, your suggested experiment has been proven by the Laws of Physics. Any 400 watt heater/device/light produces exactly the same amount of heat.

Physics undergraduate here. Not that it's relevant to this particular case.

The 400 watt rating generally refers to the power consumed by the device, not the heat radiated.

*Any light will be eventually absorbed by materials in the room, producing heat. Whether or not this heats the room in an effective way I couldn't say.