Choosing the Right Hot Water Radiator

When installing a central heating system, you will need a hot water radiator. In a hot water radiator, the heat is conveyed via a heat transfer fluid, water, which circulates in the body of your device. The radiator therefore works with a central heating system since the water is heated in a boiler (gas, wood or fuel), using a heat pump or via solar heating. It must then be brought into your device which will release the heat into your environment.

In order to choose a suitable radiator, you will need to take into account the particularities and use of the rooms to be heated. It is important to know which rooms will regularly need a good quality of thermal comfort. Transit rooms or rarely occupied rooms require a lower level of heating. Bathrooms have specific needs such as towel warmers and require a higher level of heating than any other room. In order to identify which type of radiator suits your needs, you will first need to consider the following:

• The room to be heated
• Its surface
• Your lifestyle.

There are two types of hot water radiators: the low temperature radiator and the high temperature radiator. High temperature models heat between 70°C and 90°C and are generally cheaper than low temperature ones. On the other hand, they degrade the performance of a low temperature boiler. Low temperature radiators heat between 45°C and 50°C and are more economical because they require less effort from your boiler.

You can install them in all rooms: the living room, bedroom, office and even the bathroom.

Low temperature hot water radiators (or soft heat radiators) and high temperature hot water radiators have exactly the same function. The difference lies in the temperature of the water, it is 90°C in one case and 50°C in the other.

The main advantage of not needing to heat water to 90°C is the energy saved. As this requires less effort from the boiler and the radiator itself, energy consumption is greatly reduced compared to conventional radiators. However, in order to deliver the same amount of heat with less energy consumption, a larger heating area is required. Low temperature radiators are therefore larger.

This type of radiator must also be associated with a low temperature boiler or a heat pump to operate optimally and benefit from maximum efficiency.

FERROLI cast aluminum hot water radiator

The cast iron radiator is the most classic. Cast iron radiators have the best inertia. This means they can hold and distribute heat for a very long time, even after the radiator has been turned off. However, these radiators take longer to heat up. They are also usually very heavy. Lastly, the price of cast iron radiators is quite high.

For a rapid rise in temperature, go with a steel radiator as they are known for heating up quickly. They have very thin walls that quickly accumulate and release heat but cool quickly once they are switched off. The low inertia of steel does not allow it to diffuse heat for a long period of time—compared to cast iron—and it quickly becomes cold when it is turned off. Steel radiators must therefore be installed in well-insulated rooms or used occasionally. Steel radiators are cheaper and more malleable than cast iron ones, which allows for the creation of designer radiators in various shapes, sizes and colors.

Aluminum is highly conductive material with high inertia which quickly accumulates heat and releases it slowly. With fairly classic designs, aluminum combines the advantages of cast iron and steel at an affordable price.

• Warning: Aluminum radiators cannot be installed on a circuit with cast iron or steel radiators because the incompatibility between these materials may promote electrolytic corrosion. This type of corrosion can occur when radiators of different materials are installed on the same central heating circuit. Check the material of your existing appliances before choosing to install an aluminum or steel radiator.

SCIROCCO H vertical hot water radiator

Horizontal radiators are the most popular, but the extra-flat models blend into your decor and bring a touch of modernity to your interior. Baseboard models are discrete and optimize space but they take longer to install. Of course, there are tailor-made models that can adapt to asymmetrical rooms and be installed under a sloped roof or a staircase, for example.

• Vertical radiators seem to fit well in the kitchen, especially ones with a rail to dry tea towels and washcloths.
• It almost goes without saying that for the bathroom or laundry room you’ll want a towel rail style radiator such as the ladder style towel rail, which is somewhere in between a vertical radiator and a dedicated towel rail in terms of both heat and function.
• For any main rooms, notably the dining room, you might want to choose a designer radiator so that guests feel like they’re looking at a piece of art instead of a radiator.
• Horizontal radiators fit in hallways, corridors and joining spaces best since these areas already have a long form.

The power of your hot water radiator depends on: the surface or volume to be heated, the quality of thermal insulation and the environmental exposure (winter temperatures in the region, altitude, quality of sunshine, etc.).

For a normally insulated dwelling with a ceiling height of 2.5 meters, you should provide a heating power of 100 W per m², except in the bathroom where it is recommended to count 125 W per m².

For better heat distribution in a large room, install multiple medium power units rather than one large power unit. The heat will be better distributed and the room will heat more quickly.

A hot water radiator, unlike an electric radiator, is easier to install in new construction than as part of a renovation. You will need to connect it to a hydraulic circuit, which may not have already been integrated into the home. In a renovation, it will require some work to connect your hot water radiator to your heat generator.

Feel free to equip your radiators with a thermostatic valve that will allow you to regulate the temperature of your rooms for greater comfort. You can clean the radiators with an angled brush, this will allow you to remove dust easily. It is important to bleed radiators at the beginning and at the end of winter to optimize their performance.

Here’s how to bleed your hot water radiators. First, turn off the central heating to avoid the risk of burning yourself or flooding the floor. Then put a towel under the hot water radiator that you’re bleeding to absorb potential drops. You’ll need a radiator key or a flat-blade screwdriver for each component. Identify the side of the radiator with the radiator valve and then apply the tool to loosen the valve. When you hear a hissing sound, you know air is emerging. All the air should escape before liquid comes out—at this point quickly close the valve.