Radiators
When a radiator is cold in one place the pattern usually points to the cause: air at the top, sludge at the bottom, or too little flow across the house. These entries cover what a homeowner can do and where it stops.
- Bleeding a radiator
To bleed a radiator, turn the heating off, let it cool, open the bleed valve with a radiator key until hissing stops and water appears, close it, then check the boiler pressure.
- Radiator cold at the top
A radiator cold at the top while the bottom is warm usually has trapped air in it, which bleeding should release.
- Radiator cold at the bottom
A radiator cold at the bottom but hot at the top most likely has sludge or debris settled inside, and bleeding will not cure it.
- Balancing radiators
To balance radiators, note how fast each one heats from cold, then close the lockshield valve on each and reopen it a little, opening those furthest from the boiler more.
- Lockshield valve
A lockshield valve is the radiator valve, usually under a plastic cap, that sets how much water can flow through that radiator.
- Radiator types
Radiator types on steel panel radiators count the water panels first and convector fins second, so Type 22 means two panels and two sets of fins.
- Noisy heating
Noisy central heating usually comes from air, expanding pipes, loose pipework or debris in the system, and the type of noise points to which.
- Sludge, inhibitor and filters
Central heating sludge is black debris from corroding metal; an inhibitor slows the corrosion and a magnetic filter catches what is left.