The return line connects to the equalizer through a close nipple at a point a couple of inches below the boiler's normal water line, rather than straight into the bottom. If the wet return springs a leak, the water can only be pushed out of the boiler down to that connection, leaving water over the heating surfaces. Getting the height right also limits water hammer at the connection.
No Hartford loop on this install, the return goes straight into the bottom tapping, that has to be repiped.
Also heard as
- Hartford connection
- underwriters loop
Related terms
Wet return
A steam system return line run below the boiler water line, so it always stays full of water.
Dead men
Steam heating slang for the long-gone engineers and fitters who designed and piped the steam systems that remain in service.
Low-water cutoff
A safety control that shuts the burner off when the boiler water level drops below a safe point.
Dry fire
To run the burner on a boiler that has lost its water, overheating and often destroying the heating surfaces.