CI Radiator Plugs

EBEBRATT-Ed

Working on a system that at one time was vapor. 25 years ago, they had a plumber install a HW boiler and convert it to HW.

I was there this winter when it was cold and it seemed to heat ok. Because it was vapor and now HW it never had air vents on the rads and the plumber never put any on when he did the conversion.

Instead, he installed a standard air scoop with a vent but the scoop is installed backwards. At some point someone added a Spiro vent on the return. I drained the system because of a bathroom remodel and started taking some of the 1/8" threaded plugs out of the vent tapings. Not all the rads have any vent tapings. I got 2 out with my impact they are slotted screw plugs, but the rest won't budge and I didn't want to break them.

Of course, the weather turned cold again so I had to get the heat back on. House is not occupied right now.

Somehow the air must get out eventually because it heated this winter but right now it does not heat well.

So two options.

The slotted screw plugs are not a good option to remove IMHO.

There are 1" radiator plugs at the top end of the rads. I am either going to drill and tap the plugs or try and get them out and install 1" X 1/8" bushings.

Just wondering if anyone has tapped those caps and are they thick enough to tap?

hot_rod

probably not all caps are created equal. The cast iron type seem to be plenty thick to tap.

Use an 1/8” NPT it is the finest thread pitch 1/8-27

1/4 NPT is 1/4-18

offdutytech

Give it a try with the tap it should work. Just have the new bushings on hand for a backup.

kcopp

You should be able to find a nice spot on the radiator itself. I have done this a number of times. Go slow and steady. Good amount of oil.

mattmia2

might be more meat if you drill near the edge of the plug rather than near the center. this is where you can do a lot of things with a milling machine and an end mill or d drill or other bit that isn't self feeding that you can't freehand with a hand held drill.

i wonder if there is some sort of a piloted mill that you could use like you use a hole saw on larger plugs to drill out the middle of the air vent plugs, drill a small hole in the middle of the plug with a twist drill then the mill's pilot follows the pilot hole.

aren't you retired….

Big Ed_4

If the heat is working find any thoughts of letting sleeping dogs lie … Some old conversions wanted to trap the air in the radiator and use it for expansion . Trapping air in a over size radiator is a service tip for over heating ..

mattmia2

if you put the spirovent where it belongs the air might work itself out or is the circulator on the return so you can't without moving that too?

Steamhead

I would just drill out the 1/8" plugs, re-tap the holes and install vents that way.

EBEBRATT-Ed

@mattmia2

More on the "retired " part later.😀

Big Ed_4

Old plumbers never retire , we just slow down with rules to live by.. :)