The radiator valve is broken.
ter-mo-si-FO-ne — five syllables; stress the fourth. Valvola: stress the first syllable.
Use this when you need to replace a radiator valve. In Italy, radiator problems are common in older apartment buildings, and thermostatic valves (valvole termostatiche) have become legally required in all Italian homes with centralised heating since 2017.
Termosifone is the Italian word for a radiator. Valvola termostatica (thermostatic valve) allows individual room temperature control. Italian law (D.Lgs. 102/2014) requires thermostatic valves and heat cost allocators on all radiators in buildings with centralised heating. Replacement valves must match the existing connections (usually M30x1.5 or M28x1.5 thread).
Devo sostituire la testa termostatica del radiatore.
I need to replace the thermostatic head on the radiator.
The testa (head) is the detachable thermostatic part; often replaceable without draining the system.
La valvola di intercettazione del termosifone è bloccata.
The radiator shutoff valve is stuck.
If the valve is seized, you may need a plumber; forced opening can cause leaks.
Serve la chiave da idraulico per aprire la valvola.
You need a plumber's key to open the valve.
Specific tool needed; often a valve key (chiave per valvole) sold at ferramenta.
Italy's mandatory thermostatic valve law was driven by EU energy efficiency directives and has generated enormous demand for valve replacements since 2017. Italian building administrators (amministratori di condominio) are legally required to oversee the installation of thermostatic valves in all units of centralised heating buildings. Non-compliance carries fines.