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Removing Radiator Vent Plug
Hi all, just purchased our first home and it has steam heat. I'm working my way through everything that I can (stocked up on some of Dan's books) and it brought me to a question (first of many I'm sure, but starting easy).
Many of the vents on the radiators are quite old, and I am replacing them all and starting fresh. I need to re-tap some of the holes which I'm comfortable with, not my first time - and I've done some research on this. Some of the vents are not in the middle location (taking this from the book) so I wanted to fix this. This brings me to my question...
Any tips or tricks to remove an old plug that is where I want to put my vent? Is this a hopeless exercise? You can see the vent location in the picture and then the plug below that.

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Comments
Neither will smell good on hot iron, so maybe wait for spring.
Doubtful the screw head will get it out, but who knows.
Then carefully center punch and drill out in stages.
Easy out might turn it. Not a lot of depth in the tube so caution on length of easy out.
It doesn't look like there is room to add 1/4" X 1/8" bushing, so maybe only one shot.
1st clean ALL paint off.
If the screw head is proud of the radiator, I would cut the screw thread a little deeper to get more bite.
Soaking it will help. I'd probably apply with a brush 2-3 times over 1-2 days.
Make sure your screw driver fits perfect. An "hand impact driver" can help.
I might try to apply some heat w/ a torch - it does wonders to crack all the crud in the threads.
If you do drill, take great care to get a good center.
If I do have to drill, what size bit would you start with? According to the tap I bought I'll end with 11/32".
I would go maybe 3/16 and try the easy out.
If enough of the screw plug sticks out you might carefully cave it in after drilling, it would unscrew then almost by hand.
I believe you want to preserve the existing threads and not try to create new ones. Clean up with tap, but not too deep, don't want to cut new ones deeper and lose the taper of the hole.
I would not suggest using an Easy Out. It is very easy to crack a cast iron radiator with one.
Don't ask me how I know this.
@Chris_L - do you mean in combination with an impact or just the easy out in general?
In my case, I was doing it by hand trying to get out a sheared off vent from the hole. The easy out I used was too big, and as the tapered thread went in, it hit the radiator. At that point, I was trying to expand the vent hole, and... crack
If you don't mind damaging the paint, I'd put a torch to it before trying to trying to unscrew the plug. If that doesn't work, and you are really careful abut drilling in the center, I'd make progressively larger holes and then either collapse the remains of the plug or clean it out with a 1/8 inch tap.