In previous publications, we talked about the equipment of boiler rooms in a country house. Now let’s move to living quarters to discuss the choice of final devices for water heating systems. Which of them provide maximum comfort – traditional radiators, convectors, warm floors or plinth systems?
Radiation or convection?
Heating devices of the convective type quickly heat the air, which, in turn, transfers the heat to the enclosing structures. Radiator-type devices radiate heat into the surrounding space, heating the walls and surrounding furnishings and only then the air in the room. Which of the two methods of heating a country cottage makes sense to focus on depends largely on the operating mode of the building.
Let’s see what the difference is. Let’s say you arrive at a cool house on a frosty winter Saturday for a short weekend. The room has an electric convector and a massive brick stove. You need to warm up the room so that you can comfortably spend the evening and night in it, but the task is complicated by the fact that you have to choose one thing.
So, if you prefer a brick stove that spreads soft radiant heat, you need to fire it up in the morning, and it’s even better to give the keys to your neighbors and ask them to start heating it in advance. In this case, you can expect that the next day the room will be cozy: the air is dry and relatively cool, and the furnishings you touch are pleasantly warm. An electric convector will quickly, within two or three hours, warm the air under the ceiling of the room to a “tropical” temperature – it will become stuffy and you will have to open the room, but the walls and floors will remain cold.
Of course, in either case, a comfortable microclimate will be established in the house by Sunday evening: you will be able to walk in T-shirts and barefoot on the warm floor. However, the weekend flies by quickly and you need to get back to the city.
The given example is, of course, conditional. First of all, the right stove is not only a radiator, but also a convector. Secondly, if there is a stove and a convector in the house, the owners will most likely use both. However, the conducted “laboratory work” allows, so to speak, to feel the difference.
Radiators and convectors
The market of heating devices includes both classic radiating radiators and convection-type sacramento water heaters (we will label them so as not to confuse them with direct heating convectors that plug into an electrical outlet).
Traditionally, heating devices are placed under windows. The wiring system through which the coolant circulates can be one-pipe or two-pipe. Single-pipe – less material-intensive and to a certain extent independent: in some cases it can work without an additional circulation pump. The coolant passes through all the radiators and the room in sequence, but when operating such a system in a spacious house, it may turn out that the radiators are hot at the exit from the boiler room, and barely warm at the entrance. Two-pipe wiring equalizes the chances of all radiators getting their share of heat, but for a compact house it can be an unnecessarily expensive solution.
Now we are talking about wall-mounted radiators and convectors. The traditional option, familiar to all of us since childhood, is a cast-iron battery: it is characterized by high inertia (it heats slowly and cools down for a long time), a large volume of heat carrier and a relatively low heat output. Despite the mentioned shortcomings, such radiators do not go out of use. On the contrary, decorated in a retro style, they become a fashionable interior accessory, a kind of symbol of home coziness, and they cope well with the main task – they warm up rooms even with high ceilings.
Today’s widely used steel and aluminum radiators, as well as more expensive bi-metallic heaters (copper or steel pipes enclosed in an aluminum heat exchanger) are characterized by higher heat output and require smaller volumes of coolant.
According to the design, radiators can be panels (the most democratic steel ones, which are made from stamped sheets) or sectional (when the same type of battery elements are assembled in rows). All constructive lines of heating radiators have both budget and expensive models, the quality review of which is beyond the scope of this publication.
Now let’s deal with convection heaters. The heat-reflective screen installed in front of the classic battery makes it a bit of a convector: cold air enters the radiator through the gap between the floor and the lower part of the screen and rises the walls and windows, creating a kind of thermal curtain.
The heater, sharpened for convection heating, is a pipeline with fins made of thin steel plates, enclosed in a heat-reflecting jacket. In new urban buildings and country houses, this type of economic heater is becoming more and more widespread.
The main disadvantage of convection devices is uneven heating, accumulation of warm air under the ceiling, as well as drafts that raise fine dust into the air. True, these not the most pleasant of their properties will be manifested only in rooms with low ceilings and when classic batteries are placed in regular places – that is, under windows.
The impact of these shortcomings can be minimized by placing convectors in specially provided niches on the floor and covering them with decorative grates (the heating equipment market offers options that provide for such installation). This method is common in spacious houses focused on low energy consumption. The main difficulties are the time-consuming installation (only during construction) and cleaning in the room: it is not an easy task to pick out the garbage and dust that got into it from the niche in the floor.
Warm floor and warm plinth
The main alternative to convector and radiator heating systems is water-heated floors. They are pipelines made of polymer pipes built into the concrete screed of the floor, through which the coolant circulates.
What are the main advantages and disadvantages of underfloor heating compared to traditional systems? Let’s deal with the advantages. First, warm floors provide more uniform heating of the premises. Secondly, the heat-insulated concrete screed of the ground floor of the first floor is a good thermal accumulator that will allow the room to cool down quickly in case of a sharp drop in the outside air temperature or an unplanned shutdown of the system (this feature will be appreciated by the owners of light wooden and frame houses, oriented to permanent residence).
The third important point. Underfloor heating requires a lower coolant temperature than radiators. Such a system works well with economical condensing boilers. The reverse side of the coin: it will not be possible to quickly warm up a cooled house, and the need to turn on the system at full power leads to overheating of the floors, causing the effect of beach sand heated by the sun, which is not always appropriate, especially in a still cold bedroom. Therefore, the main area of application of underfloor heating is the first floors of cottages intended for permanent residence.
Other difficulties are the need for the complex design of all building systems and low maintainability. In other words, the location of pipe heat exchangers should be thought through at the design stage, connecting them with the expected arrangement of furniture. In addition, it is necessary to mount the system only at the construction stage and, as it is called, once and for all.
Plinth heating (“warm plinth”) is a system that involves the placement of compact heat emitters in plinths around the perimeter of rooms. From the point of view of the heating method, there are two types of “plinth heat” systems: compact water convector radiators covered by a plinth casing, and direct electric heating due to low-power heating elements installed behind massive plinths. We are not considering the second option today. Warm plinths are placed around the perimeter of the premises, and such a layout has several advantages. The main plus in comparison with radiators under the windows is a more even distribution of heat. Warm plinths, even though they have a lot in common with convectors, primarily warm the walls without drafts on the floor and the accumulation of warm air under the ceiling.
Installation of plinth systems is relatively simple and possible not only during construction, but also during building repairs. The main nuance is the need to think about the placement of the furniture in advance, because there is little point in using a battery behind a sofa or a closet. However, if you want to rearrange the “warm plinth”, it is easy to move it.