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Hi, I've had an recurring (but occasional) problem with spitting and dribbling vents. It seems to happen especially but not only during cold spells.Since I took over the building some 13 years ago I've tried to eliminate problem after problem. At this stage all radiators are properly pitched, improperly pitched piping has been corrected or eliminated and vents have been replaced as necessary. The system is almost silent and, for the most part, works well.
I recently had a local steam system expert come and diagnose the issue. He saw two issues.
First, an oversized boiler. It's a Burnham that was originally used with oil (from 2003) and then switched to gas in 2009.
Second, undersized risers throughout the 4-storey building. Eight risers in total. Four are 1 1/4" and 4 are only 1".
(If the diagnosis is correct the it would appear the Dead Men made an uncharacteristic error...?)
Strangely, on the top floor the risers have a reducer coupling and the riser pipe size increases to 2" until it stops just below the ceiling. The local expert advised eliminating these sections and replacing them with a 1' long pipe 3/4" ID, topped with a master vent.
He also recommended adding vents to the mains and the top of the risers and putting slower venting air vents on the radiators. And adding a vaporstat, which is on order already.
I'd be grateful for any second opinions on all of this and about whether downsizing the boiler is possible.
Or actions that can be taken to stop the spitting vents etc.
Thanks in advance for any thoughts on all this.