Radiator Sizing Guide

Choosing a system that is not sized correctly will cost you money in poor power consumption. Correct sizing calculations should only be carried out by a qualified specialist and Central Heating’s technicians are well experienced in calculating the correct system requirements for your project. The size of radiator required for a room depends upon two factors: The temperature that you want it to be able to maintain and the amount of heat loss that will occur in each room

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As an example on how to determine the heating demand of a home, you need to calculate the heating capacity using the dimensions of the home. You need the length, width and height measurements. You need to consider the number of doors and windows in the home, and you need to consider the location of the home as the weather can affect the heating efficiency of the system.

A basic calculation would be as follows:

Floor’s area: length x width=square meters
Volume: square meters x height=cubic meters
The value of required thermal power: cubic meters x 40W= grosswatts
Each window will add another 100 watts, and each door will add another 200. Gross watts+window watts+door watts = total watts
A home uses a heating coefficient of 1.5. This calculation would be: total watts x 1.5=new total watts
The location weather coefficient: new total watts x location weather coefficient= Final total

This basic calculation will give you an idea of the size of system you will need to ensure efficient heating for your project.

Please note: This is a guide only. For accurate calculations please contact us for an engineered solution.

Humans are not cold blooded creatures and as such enjoy an ambient heat to live comfortably. The most commonly suggested temperatures for happy healthy living areas are:

IDEAL ROOM TEMPERATURES

Lounge	21c
Dining Room	21c
Kitchen	16c
Bedrooms	16c
Bathroom	23c
Stairs	18c

The amount of heat that is lost from each room is not an easy calculation. In fact, to figure it out it can be quite complex. There are a number of factors that need to be considered such as: the size of windows, the number of doors and, in particular, the construction materials used to build the house.

“U” Values

U-values measure how effective a material is an insulator. The lower the U-value is, the better the material is as a heat insulator. If you have not got the calculations right when sizing your radiators, then you will be left with some less than ideal issues. If you calculate incorrectly and install radiators that are too big for your space, then your system can surpass the set temperature and become very uneconomical to run. If you calculate incorrectly and install radiators that are too small then you will be left in the cold, so to speak, as the system will not be able to reach comfortable temperatures for your space.

Although there are plenty of calculators to be found to “help” the best DIY enthusiast Central Heating recommends leaving the calculations to their experienced technicians. We have the expertise to get the formulas right, first time, so that you have a warm comfortable environment within your home.

Positioning Radiators

There’s a couple of reasons why you will generally find radiators installed under windows. Unless you have double glazing you will likely find that there is a steady stream of cold air that leaks in around your window frames. Cold air falls whereas warm air rises. By placing a radiator under a window, the rising heat from the radiator tends to combat any falling cold air that might leak into your room – resulting in a more stable temperature. If you install a radiator opposite to a window then you can run the risk of creating quite a noticeable draught, since one side of the room has warm air and the other has cold air falling.

It is always a good idea to make the most of any space available in a room. Usually the space under a window is not used, and doesn’t have furniture placed by it. By installing a radiator under a window you get to make use of this space. There are many different designs of radiators available in the marketplace so you should be able to find something that will complement your décor. Almost all radiators come in a standard white, and most can now be painted to match your wall colour. If you don’t like the idea of this, there are custom surrounds that can be purchased to disguise them.