Energy myth-busting: Is it cheaper to have heating on all day?

richardc1983

Radiant on it's own will take longer, convection and radiant combined will warm it quicker. Our towel rad got red hot, but it didn't warm the room even with no towels on it, particularly at lower flow temps they have less surface area so the output is poor.

QrizB

richardc1983 said:

... they have less surface area so the output is poor.

Perhaps your opinion is coloured by experience with an undersized towel radiator?

The example I linked to a couple of pages back had about 20 metres of tube and a surface area of about 1.4 square metres.

I've no reason to doubt BUFF's sincerity when he says these are tested under the same conditions as radiators are, and rated in the same manner.

Do you have any citable evidence that towel rails fail to provide their rated heat output in real-world settings?

BUFF

QrizB said:

I've no reason to doubt BUFF's sincerity when he says these are tested under the same conditions as radiators are, and rated in the same manner.

Do you have any citable evidence that towel rails fail to provide their rated heat output in real-world settings?

https://www.iea.org/policies/7036-en-442-122014-radiators-and-convectors

QrizB

Thanks BUFF!

With you posting that for everyone's information I think I'm done discussing the performance of radiators in this thread.

BikingBud

Did i really read all that.

I fully support the answer: it depends!

Trying to draw comparisons between old systems in old houses and idealised, well designed systems with optimised controllers, in a well insulated house, using up to date technology it is clear which will follow the laws of physics most efficiently.

However, as heating systems, house insulation levels, personal preference (prejudice) etc vary, I think he mentioned 7 variables, then this debate becomes a standard internet argument where nobody is wrong and nobody is correct as everybody has a different set of circumstances that they focus upon.

Most people seem to want a cheap heating system that just kind of works, they do not invest in the system that would give best control and efficiency, they do not invest in understanding how to optimise the system if at all possible. Focus on and demand for energy efficient systems is currently extremely low but people seem quite happy spending loads on a shiny new kitchen  

richardc1983

BikingBud said:

Did i really read all that.

I fully support the answer: it depends!

Trying to draw comparisons between old systems in old houses and idealised, well designed systems with optimised controllers, in a well insulated house, using up to date technology it is clear which will follow the laws of physics most efficiently.

However, as heating systems, house insulation levels, personal preference (prejudice) etc vary, I think he mentioned 7 variables, then this debate becomes a standard internet argument where nobody is wrong and nobody is correct as everybody has a different set of circumstances that they focus upon.

Most people seem to want a cheap heating system that just kind of works, they do not invest in the system that would give best control and efficiency, they do not invest in understanding how to optimise the system if at all possible. Focus on and demand for energy efficient systems is currently extremely low but people seem quite happy spending loads on a shiny new kitchen  

You are right, over in Denmark and Germany they have plant rooms and they are proud of the equipment. When they spec their systems they do it to the same standard as we choose a bathroom or a kitchen fit out. 

Petriix

No, it doesn't depend... More heat = more heat loss. It's objective fact. There are many variables which can make it more difficult for people to observe the basic physics at play, but the fundamental principle is unquestionable.

richardc1983

But the point many of us are trying to make is less heat such as 18/19c 24 hours a day with say as low as 30c flow temp (low and slow because the house fabric is already maintained) is potentially less heat loss than 22/23c 8 hours a day and off in between with 70/80c flow temp. The higher comfort temp and flow temp is what is using more gas POTENTIALLY. 

 Petriix said:

No, it doesn't depend... More heat = more heat loss. It's objective fact. There are many variables which can make it more difficult for people to observe the basic physics at play, but the fundamental principle is unquestionable.

Spies

Higher the difference between internal and external temperatures (The Delta-T) means more heat loss, the closer to Delta-T the less heatloss you get.

Ultrasonic

Most people seem to want a cheap heating system that just kind of works, they do not invest in the system that would give best control and efficiency, they do not invest in understanding how to optimise the system if at all possible. Focus on and demand for energy efficient systems is currently extremely low but people seem quite happy spending loads on a shiny new kitchen  

Most people probably replace a kitchen when it needs doing, and do the same with a boiler. It also probably doesn't make financial sense for most to replace all but the oldest/most inefficient of boilers.

Replacing a boiler is also not an option for the huge number of people who rent their homes.