Calculating the KWh to heat a room

pothole50

I have been onto a site which calculates the BTU's to heat up a room site is here.

http://www.homesupply.co.uk/radiator_output_calculator.php

I put in the calculations for the room 3.66m x 2.44m x 2.29m one window, one outside wall, heated room below and the fiqure came out as 471W and BTU 1609, I have put a 500kw heater in there and its no use at all, so are these just ball park figures.

macman

I think you mean a 500W heater-a 500kW heater (in theory) would do the job very quickly indeed-unfortunately it would blow the service fuse immediately.
A 500W heater is the power of just 5x100W light bulbs-you can heat a room with that, but it'll take forever. Most convectors are 2kW or higher.

rogerblack

In short - yes.
It's making hugely simplifying assumptions.
The proper way to do this involves working out how leaky the room is, and then going into detailed calculation to work out the insulation value per surface, which may involve working out what's actually behind the surface which can involve holes in walls.
In practice.
Measure the temperature.
Put on a 1kW heater all the time.
Measure the temperature after 5 hours (say) (during a time of day with little wind, and a constant temperature - overcast days are good).

If the temperature rise is 10C, and you need a 15C temperature rise, you'll need 15/10 = 1.5*1kW of heat = 1.5kW.
This should be good to around 10% or so.

energysavingexp

500KWh heater dont think so you could heat a very big building with that plus you would need one hell of a cable for that

pothole50

What a plonker I am 500kw :-)

HappyMJ

pothole50 wrote: »

I have been onto a site which calculates the BTU's to heat up a room site is here.

http://www.homesupply.co.uk/radiator_output_calculator.php

I put in the calculations for the room 3.66m x 2.44m x 2.29m one window, one outside wall, heated room below and the fiqure came out as 471W and BTU 1609, I have put a 500kw heater in there and its no use at all, so are these just ball park figures.

Is the room below actually heated? How many external walls-are you sure it's just one-Most people should have 2 or 3(the rooms on the other side must be heated too)? Do you want the room to be cool (for a bedroom) or warm (for sendentry work such as in a home office-pick lounge). Do you really have 100mm of insulation? I'd play about with the entries and use the worst case scenario. I'd use a 1,500W radiator or thereabouts. The 471W will just maintain the temperature at 18 deg C it won't be any good at bringing the room up to temperature quickly.

bengasman

pothole50 wrote: »

I put in the calculations for the room 3.66m x 2.44m x 2.29m one window, one outside wall, heated room below and the fiqure came out as 471W and BTU 1609...

Just goes to show how useless this exercise is; it took me about a second to work out that 471W was miles off.

Meepster

Using the old (rough) way of working out the MINIMUM BTU rating of the room (doesn't take into account insulation) I get it to be 4368 BTUs (around 1.28kw)

Very old and basic equation = length (feet) x width (feet) x height (feet) x 4 (downstairs) or x 5 (upstairs)

Then add an extra 10% for each window and door, 20% each for no wall insulation or no roof insulation or each external wall

pothole50

I have just had this http://www.argos.co.uk/static/Product/partNumber/4159201/Trail/searchtext%3EOIL+FILLED+RADIATOR.htm in there for 1 hour waited for it to heat up and looked at temp was 13.2 inside and 7 out, an hour later it was 13.6 it seems to be doing absolutely nothing at all, the rad feels red hot but gives off little heat into the room. Then I waited for the oil filled to cool down and now trying this http://www.currys.co.uk/gbuk/logik-l15cfs10-ceramic-fan-heater-1-5kw-06708497-pdt.html set on speed one which is also 750w,which I bought yesterday and really impressed with it as its the first time I have tried a ceramic one, I have a fancy Dimplex Glow Fan 2kw fan heater, but both set up side by side moving away from them you can still feel the heat coming from the cheap curry one, could that be because one is a wire heating up so the fans cooling it down, the other is the ceramic so appears to give out more heat. Yes I know after reading numerous threads on here that they all give out exactly the same no matter what type of heater it is, just checked after an hour and its 16.2 inside and 6.5 out.

more_control

Does anyone know how to calculate the actual running costs BTU/KW of a radiator. I know how to measure up a radiator and know how to calculate a room size and to get an approximate value on the running costs / heat, energy loss of a radiator in a given room.

The reason I ask, is that we have developed a radiator value that can allow you to program / preset each radiator in a house hold to optimise your energy output.

The only problem I’ve come across is working out a scientific means of measuring energy use from a radiator. The calculators and variables I have seen give you a rough understanding of energy use in relation to the room.

What I am looking for is to find out a means of knowing how much energy it would take to heat up a room from one temperature to another and how much energy it would cost to keep it at constant value.

Example:
Heat up from 13-17 degrees and to know how much energy it would take to keep the room at that level. In terms of mins/hours Given the energy loss from the radiator, the room and the temperature outside.

Whether there is a means to calculate energy/ fuel burned or the temperature of hot water returning to the tank.

If anyone has any suggestions, let me know.

Many thanks.
Steve

penrhyn

more_control wrote: »

Does anyone know how to calculate the actual running costs BTU/KW of a radiator. I know how to measure up a radiator and know how to calculate a room size and to get an approximate value on the running costs / heat, energy loss of a radiator in a given room.

The reason I ask, is that we have developed a radiator value that can allow you to program / preset each radiator in a house hold to optimise your energy output.

The only problem I’ve come across is working out a scientific means of measuring energy use from a radiator. The calculators and variables I have seen give you a rough understanding of energy use in relation to the room.

What I am looking for is to find out a means of knowing how much energy it would take to heat up a room from one temperature to another and how much energy it would cost to keep it at constant value.

Example:
Heat up from 13-17 degrees and to know how much energy it would take to keep the room at that level. In terms of mins/hours Given the energy loss from the radiator, the room and the temperature outside.

Whether there is a means to calculate energy/ fuel burned or the temperature of hot water returning to the tank.

If anyone has any suggestions, let me know.

Many thanks.
Steve

Thought we already had TRVs, maybe those manufacturers have some calculators.
The imeasure site I use has a degree/day graph which might help.