CI Radiator Plugs

EBEBRATT-Ed · March 15

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 · March 15

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 · March 15

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

kcopp · March 15

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 · March 15

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 · March 15

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 · March 15

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 · March 15

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

EBEBRATT-Ed · March 15

@mattmia2

More on the "retired " part later.😀

Big Ed_4 · March 16

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

109A_5 · March 20

@EBEBRATT-Ed can you drain the system, pull a vacuum on it to get more of the air out, then refill and bleed the radiators that you can ?

pecmsg · March 20

Coobeast 35 Pcs Screw Extractor and Left Hand Drill Bits Set, Easy Out Screw Extractor Kit with HSS Steel Reverse Drill Bit for Broken Nuts, Stripped Bolts Remove - Amazon.com

Has made drilling out problems easy!

Grallert · March 20

I like to drill and tap the plugs out but I use reverse twist drills on the off chance the plug will back its self out while drilling. It happens sometimes.

pecmsg · March 20

https://forum.heatinghelp.com/discussion/comment/1892302#Comment_1892302

I found it happens most times. Just the heat generated helps.

Intplm. · March 20

Is it in your plan to move the Spirovent and installing it where the air scoop is? Maybe cut in a purge tee(s) on the return? That might be enough.

EBEBRATT-Ed · March 21

I am just going to reverse the air scoop with a new vent on it and put vents on all the rads leave the spirovent on the return as is. Air scoop is 1 1/4 and the Spiro is 1" so I am not going to repipe the whole thing.

It heated ok before I drained it so the air must eventually get back to the spiro vent but I get impatient in my old age.

Big Ed_4 · March 21

Don't use easy-outs on cast iron , drill and tap only ..You don't want to hear that crack …

pecmsg · March 21

https://forum.heatinghelp.com/discussion/comment/1892492#Comment_1892492

that’s the idea of reverse drills.

hot_rod · March 22

I would first try drilling out the slotted screw brass ones. Brass is easy to drill, and the casting must be thick enough where they are now. Even if you need to go up one size, maybe from 1/8- 1/4” it may be easier than drilling an unknown plug?

EBEBRATT-Ed · March 22

@hot rod, the unknown plugs are 1". Worst case if I drill one and it is too thin to tap cutting one out with the Sawzall wouldn't be that bad then put a 1 x 1/8 bushing in. I think the plugs will probably be thick enough

hot_rod · March 22

I've drilled and tapped into a number of schedule 40 nipples with 1/8 and 1/4" NPT. Works fine on low pressure hydronic systems.

For building pressure tap ports around circulators.

Use a dab of Expando for a tight seal.

CI Radiator Plugs

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