How Vacuum Can Form in a Steam System

HeatingHelp

How Vacuum Can Form in a Steam System

This is how vacuum can form in a steam heating system and how to fix it.

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CastIronGuy

I hope that pic wasn't the new Weil-McLain LGB boiler he installed - look like that one in the picture needs a rest & some love!

jumper

If I understand correctly these are cases of pressure difference overwhelming control valves?

I've seen similar in other situations as well.Discrete (on/off) control like zone valve is needed.

I've seen advertisements for "snap action" float controls. Will they work in these cases?

EBEBRATT-Ed

I had that exact same issue on a new boiler install. I fixed it a little different. I ran the feed from the boiler feed pump through a check valve and then up in the air above the water level in the boiler and the feed tank and put a vacuum breaker at the high point before dropping down into the boiler. Worked fine

jumper

https://forum.heatinghelp.com/discussion/comment/1805460#Comment_1805460

Elevated condensate tank with level control sounds fool proof. In some cases you can pressurize the tank with steam instead of atmosphere.

Mad Dog_2

Till this day, it still amazes me that a man who never turned wrenches for a living, nor was he an engineer, could read, decipher, figure out and then regurgitate it in plain english mpto the Installers…I haven't seen a teacher that has done this is any other industry save, Olympian Mark Spitz' (7 Golds in 1972 Olympics) coach, who did not know how to swim himself!! Great explanation Dan..Mad Dog 🐕

jumper

I'm more amazed by the opposite of what Mad is. How so many intelligent mechanics, engineers, and non-specialists can overlook the obvious for years.