Hydronic boiler controls

GeoKnight

Hey guys I wanted to know what this component is on this Weil-McClain 140000btu hydronic boiler. This piece is where I believe an air separator should have been because the system doesn’t have one. Instead this is about 20”


downstream of the expansion tank on the supply piping. I’ll also add a few pics of the boiler/piping itself.

hot_rod

That is a swing check valve. A flapper inside slides down when the circulator stops tom prevent unwanted flow

EBEBRATT-Ed

Flow check valve

And if you only have one zone and no domestic hot water from the boiler you don't need it

neilc

is that expansion tank supported?
or just dangling at the top of the 1/2 inch copper?
please support me

GeoKnight

neilc said:

is that expansion tank supported?
or just dangling at the top of the 1/2 inch copper?
please support me

You cant see it but the horizontal pipe it’s connected to it clamped to the floor joist.

GeoKnight

EBEBRATT-Ed said:

Flow check valve

And if you only have one zone and no domestic hot water from the boiler you don't need it

So it has about 5 baseboards with no zoning they all branch from the main poorly insulated pipe you see with no domestic water zoning. So I suppose I can put an air separator in place of that?

EBEBRATT-Ed

Maybe they had domestic hot water off the original boiler but with only one zone and no DHW off the boiler you don't need it