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"Radiator Mess"! Radiator Designs and use.
Why not better than developed countries?
by Hakan Falk at Energy Saving Now. (energysavingnow.com)
To better understand the design and use of radiators, you should as a minimum first read the "Make it comfortable for real People".
Introduction to Radiator Designs and use.
We do not know where or when the engineering community went wrong and only started to look at air temperatures. It probably has to do with the education system in combination with the introduction of simplified calculation methods based on U-values. As I stated elsewhere the need of massive education meant a great loss of both scientific and empirical knowledge. I also think those ignorant Building Standards, developed with too much commercial interests, carries a large portion of the blame. The result is a nearly total anarchy in design of heating systems, with an enormous "over consumption" and need of energy. Anyone who understands the basics of what we are trying to communicate on "Energy Saving Now", will quickly develop an understanding (and frustration) of why we have those totally uncontrolled energy crises with black outs etc. In the following I will try to address the "Radiator Mess".
Types of Radiators/Convectors.
Radiators are as defined by the name, a heating source (under certain conditions cooling, but not discussed here) that originally was designed mostly to transmit heat by radiation. Electricity, flammable or a liquid medium normally heats it, the last is most commonly water. The radiators will transmit heat to the body by radiation and by indirectly or directly heat air. In this sense it emulates the sun, which transports energy purely by radiation. The sun only indirectly heats the air, by heating up surfaces.
Radiators can mainly be divided in five groups and there are also many combinations of the designs.
- Direct Source Radiation.
- The Reflector Designs.
- The Flat Panel Designs.
- The Radiator/Convector Designs.
- The Convector Designs.
In the following chapters, we will describe the different types of radiators,
Direct Source Radiation.
This is the direct radiation from sources like the sun, campfires, open fireplaces etc. The sources is less efficient both from radiation and burning point of view, i.e. The burning of wood in often in open fires, which has so low temperatures that the efficiency is less than 30% and the pollution very high. The burning processes can be enhanced and when they reach over 800-1,000 centigrade for wood, when the coal and gases also start to burn. Such a burning process will be more efficient and give less pollution. It requires however closed insulated spaces and a three step burning process.
The Reflector Designs.
The reflector designs goal is basically to direct the radiation energy in a wished direction or spreading to get an even radiation heating. Samples of this are the infrared electrical radiators use on open terraces, winter gardens or greenhouses. Other samples of spreading and reflection is the now popular party heater, that looks like an old time street lamp, or the very common gas catalysator burner.
The Flat Panel Designs.
 The flat panel design is based on one flat radiator panel heated by electricity or liquid medium, often water. It is basically used to radiate heat and is therefore dependent on the surface area. The design is often easy to adjust to the body system, since it produces more radiation of heat than warm air. The reality is also that it occupies larger visual space, since its capacity is dependent on exposed area. Samples of panel designs are of course the obvious wall mounted radiator, but heated floors, walls and ceilings also falls in this design category.
It is however the best alternative for heating system in constructions that are not very well insulated and sealed. Often it gives a good perceived temperature and reduces the needed room temperature with 2-4 centigrade (if correctly used). This means also that the capacity requirement, should be around 30% to 40% lower than a more convector based design and is also an indication of normal energy savings.
The Radiator/Convector Designs.
This is a radiator that combines radiator designs with often-elaborated designs to enhance the production of warm air. There are some applications where this could be an advantage or necessity, but they are not common. The designs are not adapted to the human system, they rather relies on the human system to compensate the lack of radiation with the over production of warm air. The waste of energy can be around 40 to 50%, (depending on how insulated and sealed the construction is) and it must be good reasons to accept this.
Unfortunately and with reasons that go beyond the author's comprehension, it is the most used radiator design. It is also most commonly used in constructions that are poorly insulated and sealed, like the predominant use in Spain. The result is also that it creates designs that are not only grossly over-dimensioned, but also very difficult to adopt corrective regulation methods for energy savings.
The Convector Designs.
The convector design is by definition not a radiator. It is a device that transmits heat/cold to air temperature. But this article would not be complete, if we do not include the designs and its uses.
For thousands of years, convector designs were used to accumulate and convert heat to radiant heat sources. The Arab and Roman engineers used clever duct systems in the buildings to use them to accumulate and radiate heat. Their understanding and designs, outperforms much of today's designs and engineering knowledge. Until around 70 years ago, the common stoves used convection systems to heat up and accumulate in radiant constructions. A modern scaled up version of these systems is the "Thermodeck" system developed by Engelbrekt Isfelt (co founder of this site). The "Thermodeck" system can give up to 70% energy savings in modern buildings, with equal or raised comfort.
The common use of convectors today is in "Air Conditioning" systems. Even if it can be a case for using this kind of systems, they require well insulated and sealed building constructions, otherwise they are a synonym for enormous energy waste and stupidity. The original common use was in sensitive environments like the old computer rooms or laboratory environments. Today it is not words, to describe the (mis) use and over-dimensioning of "Air Conditioning" systems. California would not have an energy crisis without them.
Convector designs have an extremely important application in energy accumulation and recuperation. As it had during thousands of years. The old designs are logical and in many cases very energy efficient. We only have to use the "new and important research" for the right things and start to save energy instead of waste energy.
Location of radiators.
Where and how to locate the radiators are important issues. If you have read "Make it comfortable for real People", you know that the surface temperatures are more important for the body system than the air temperature. Correct type and location of radiators are essencial issues. Wrongly placed radiators will result in a need for higher air temperatures to compensate loss in comfort and with substantial energy waste.
A heating system that keep radiators warm with pulsating or shunt valves. Radiators placed on walls to the outside and under windows, will compensate for low surface temperatures and the room temperature can be kept lower with maintained comfort and around 10% energy savings for each degree Celsius (C) lower air temperature.
As a sample can be mentioned the typical Spanish house that will have the same or lower comfort at 22 to 24 degree C air temperature, as the Swedish have at 18 degree C. Thogether with other construction priciples, insulation standards, HVAC systems and climate control, the Swedish house uses only 25% energy, compared to the Spanish (after correction for the climate).
Conclusions.
It is still hope! With all the good engineering channeled to more efficient things and with a good re-thinking of the design and use of radiators/convectors, we can in short time achieve spectacular savings both in energy consumption and first time equipment cost. It would also be good if the producers/suppliers of different kind of solutions could put away the interest of selling the higher price items, in favor of technical correct solutions. The cost for the customer in higher energy consumtion is much larger that the extra gains for the supplier. It is better to pay more for a simplier but correct solution with less expensive radiators, than pay for the future energy waste with more expensive radiators.
A more realistic use, adopted to the actual building construction and the human body, can achieve energy savings in very short term. The savings possible is around 30% for existing buildings and in new new buildings it can be higher than 50%.
Let us do it better, it only takes a little bit education and understanding of fairly simple principles.
Hakan Falk
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