Call a pro: a radiator or baseboard that stays cold

Why this happens

Weil-McLain's steam boiler manual lists faulty air vents or traps, clogged pipes, valves or radiators, a closed radiator valve and an incorrect pressure limit setting as reasons some radiators or baseboard units do not heat, and says to have a qualified service technician inspect, repair or replace faulty air vents or traps and clean or replace clogged parts. It also says its boiler and burner adjustment pages are only for a technician. NYCHA says that if the pipes are hot and the radiator is cold with the valve open, the radiator trap may need to be changed. Slant/Fin says air pockets can block circulation in hot-water baseboard. This Old House and Bob Vila describe bleeding air out of a hot-water radiator, and This Old House says that if no water comes out, the clue points to the basement. We leave bleeding to your heating pro. Broxtowe Borough Council in the UK says bleeding a radiator on a sealed system lowers the pressure of the whole system, and City of York Council tells tenants with a sealed combination boiler not to bleed their radiators. Both are UK councils, so this wording comes from UK systems. Topping a system back up is boiler work. So if someone already bled this radiator and it is still cold, that is a good reason to call.

What to do right now

1. If you smell gas, see smoke or flames, a carbon monoxide alarm sounds, or anyone feels dizzy or sick, leave now and call 911 from outside.
2. Note what you find. Is the radiator cold at the top and warm at the bottom, cold all over, or cold while the pipe feeding it is hot? Write it down for the pro.
3. Do not bleed the radiator, do not add water, and do not change the boiler's pressure. Do not touch the boiler's fill or feed valve, pressure relief valve, burner, controls, pilot, flue or gas valve, and do not open or drain it.
4. Do not force a stuck valve, and do not open, repack or take apart a radiator valve or air vent.
5. If a radiator or pipe is leaking water or steam, keep children and pets clear and call right away. New York City's housing department says steam radiators can reach 220 degrees F and that corroded pipes or faulty valves can make one rupture without warning. If a pipe has frozen or cracked, use the frozen pipe page linked below.
6. Call an HVAC technician or licensed heating contractor. If you rent, tell your landlord or property manager as well. NYCHA tells its residents to report heat problems, and New York City's housing department says tenants can call 311 if an owner does not fix a radiator.

When to stop. If a radiator or valve leaks water or steam, or looks damaged, keep everyone clear and call right away. If you smell gas, see smoke or flames, a carbon monoxide alarm sounds, or anyone feels dizzy or sick, leave and call 911 from outside.

Start this troubleshooter over

FourHome is our sister brand. Browse all FourHome replacement faucet and shower parts on the FourHome Amazon store. We earn from purchases made through this link.