ᐅ Why Radiators Are Not Installed on Central Interior Walls

In my inherited house, there are currently oil-fired furnaces with a central oil supply.

If I install the gas condensing boiler, I could place the radiators where the oil furnaces are now. These are arranged around the centrally located chimney.

This would allow for a quick and cost-effective installation through a service shaft.

What are the reasons against not placing the radiators under the windows / on the exterior walls?

DRDRWHO schrieb:
What are the disadvantages of not placing radiators under the windows / along the exterior walls?

Heat transfer from the indoor air to the outside occurs mainly through the building envelope, in addition to ventilation losses. Exterior walls are therefore always colder than interior walls, and outside temperatures are generally lower than inside.

To counter this, radiators have traditionally been installed on exterior walls, typically below windows. Windows have always provided less thermal insulation compared to the rest of the walls, making them the coldest parts of the exterior wall. By placing radiators under the windows, heat is released at these points, creating a more even indoor climate. This arrangement prevents drafts caused by warm air in the center of the room and cold air near windows, reducing corresponding air currents. It also helps prevent condensation and moisture buildup on windows and exterior walls, especially in corners.

I deliberately use the past tense "have had, were, and helped," as times have changed in this regard.

Modern triple-glazed windows and thickly insulated exterior walls have made radiators under the windows mostly unnecessary, since even radiators located away from exterior walls now experience only minimal temperature differences. Instead, low-temperature underfloor heating systems are now favored. However, these systems only work effectively in houses with suitable insulation standards for walls, roofs, floors, and windows. Placing radiators in the interior of the house is essentially the opposite of the original design concept and only functions well with well-insulated exterior walls (U-value <0.2) and modern windows (Uw <0.95), as well as low ventilation losses.

In older buildings, this approach will first be very uncomfortable and second may lead to moisture damage within the walls.

Apart from drafts, radiation effects (a cold window that emits less heat indoors versus, for example, a warm stove) are crucial for thermal comfort. By skillfully utilizing these effects, the actual room temperature can be kept several degrees lower while maintaining the same level of comfort.

dertill schrieb:

In older buildings, this will 1. be very inconvenient and 2. can lead to moisture damage in the walls!

Well, theoretically maybe. In the OP's house, it seems to have been unproblematic like this for many decades.

DRDRWHO schrieb:
If I install the gas condensing boiler, I could place the radiators where the oil stoves are now. These are arranged around the centrally located chimney.

I consider it one of the biggest mistakes in our building culture to have given up on having a stove in the center of the house. Your plan seems worth considering.

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