Radiator installation and replacement

When is it worth replacing a radiator?

A water radiator lasts for decades, but sooner or later you run into a leak, a rusty surface or a valve that no longer controls the heat. Radiators are also often replaced during a renovation, when a room's use changes or the old model does not suit the new interior.

The whole radiator does not always need replacing. If a room is too cold or too warm, the cause is often the thermostatic valve or its setting. Replacing the thermostatic head is a small job, but replacing the valve body requires the heating system to be at least partly drained.

A working thermostat reduces the flow of water to the radiator when the sun, appliances or people warm up the room. A stuck thermostat does not react, so the room overheats and heating energy is wasted. Consider a replacement or a closer inspection if you notice any of the following:

• a leak or damp marks at the joints or valve
• the radiator heats unevenly even after bleeding
• the thermostat is stuck and the room temperature does not change when you adjust it
• the surface is rusty or the radiator is damaged

Choosing a radiator, and the price

The size of a new radiator is chosen according to the room's heat demand and the flow temperature of the heating system, not by appearance alone. A radiator that is too small will not keep the room warm in a hard frost.

If you are switching heating systems, for example from oil to a ground-source heat pump, it is worth checking the radiators at the same time. A heat pump works most efficiently at a low flow temperature, in which case old radiators may no longer give enough output.

You can buy the radiator yourself or agree that it is supplied as part of the job. Before buying, check the connection type (side or bottom connection) and the distance between the connections, so the new radiator fits the existing pipes. Because the number of radiators, the valves and the pipe changes vary, the price is always given as a quote. In a detached house, you can claim the household tax credit (kotitalousvähennys) for the labour part – estimate its effect with the calculator on our prices page. In a housing company, radiators are usually the company's maintenance responsibility, and then a shareholder gets no deduction, even when paying for the replacement personally.

Draining, refilling, bleeding and balancing

Before the old radiator is removed, the heating system or part of it is drained. Once the new radiator is connected, the system is refilled, the joints are checked and the system is bled. At the same time, we make sure the system pressure is right. After refilling, air can keep rising into the radiators for a few more days. In a detached house, you can bleed them again yourself with a radiator key – see how to bleed a radiator. In a housing company, this is usually done by the maintenance company (huoltoyhtiö).

Finally, the valves are adjusted. In balancing, each radiator is set to the right flow rate, so that the rooms furthest away get enough heat and the nearest ones do not overheat. In older systems, balancing has often never been done, and balancing alone can noticeably improve comfort. If the system is in poor condition overall, read more about radiator pipework renewal.

Soldering copper pipes is hot work. The installer holds a hot work card (Tulityökortti), and the work is carried out with fire risks in mind.

Replacing a radiator in a housing company

In terraced and apartment housing companies, radiators and the heating system are usually the housing company's maintenance responsibility. So first submit a renovation notice (muutostyöilmoitus) and agree on the replacement with the property manager (isännöitsijä). The housing company may require a specific radiator model or output.

In a block of flats, the heating water circulates through risers that serve several flats, so replacing even a single radiator may require shutting off and draining a riser. Draining and refilling are therefore arranged with the maintenance company, and neighbours are told about the shut-off in advance. If the housing company has a balancing plan, the new radiator's valve is set to the value in that plan.