How can you drill and tap a radiator vent hole and still use the original 1/8" vent size?

CoachBoilermaker

Missing something basic.

The 1/8" tap is only used to clean the threads, right?

In the video, he uses an 11/32" drill bit. That is much larger than 1/8 (or 4/32). In fact, that is 3x larger !!

If you drill out the hole, it's now bigger than the original 1/8" and the vent will be too small for the enlarged hole?

https://youtu.be/y3I1N2NTqqE?si=qGpJ7Z-44CVD1bcR&t=92

ethicalpaul

1/8 is the inside diameter. The pipe itself and its hole is indeed larger

EdTheHeaterMan

When you look at a 1/8" pipe's outside diameter and 1/8" on a standard ruler or measuring tape, it will become much clearer.

And any tap can be used to clean up threads of an existing opening of that particular dimension. But that is not its only function! (answer to "The 1/8" tap is only used to clean the threads, right?" is NO). I have also drilled a hole in a material and used a TAP to make threads in that hole. We are talking about using the suggested drill size to match the tap that will offer you the threads needed to get the job done. Nothing different that what you might do with any piece of machinery.

HomerJSmith

"The 1/8" tap is only used to clean the threads, right?" Not necessarly.

"1/8" NPT pipe tap uses an 'R' size drill bit. Because the tap is tapered you can re-tap the hole which will make it a little larger and the vent would screw in a little deeper. That way you would cut a deeper thread into new metal.

If you have a broken piece of the vent in the hole, you might try an easy-out to remove it. Screw the easy-out into the broken part and than tap the easy-out lightly with a hammer on the end of the easy-out to loosen the threads.

EdTheHeaterMan

I am wondering if @CoachBoilermaker

actually has a problem? OR Is he getting prepared for one?

I believe that all his vents are removable however the fact that out of 100,000 vents in 100,000 radiators, there may be 50 that broke off, Our Coach is having anxiety attacks over the thought of attempting this daunting task. It is entirely possible that the folks that owned the home before you, swapped those vents out within the past 10 years, and that the vents you have are not 80 years old.

CoachBoilermaker

https://forum.heatinghelp.com/discussion/comment/1814450#Comment_1814450

Correct.

Before I tackle DIY project I always try to figure out what could go wrong. I don't want to be left hanging with a limbo situation. One thing I've learned in car mechanics is that if something can go wrong it will. A simple half hour job can become an 8-hour job. I'm very careful not to bite off more than I can chew and get in over my head. If it goes well unscrewing event looks like a 5-minute job. Or it could crack off and disable the entire heating system for a week until I get a tech to tap out the thread or whatever if the vent cracks or crumbles while I'm removing it.

I'm assuming if they're vent cracks off and leaves a gaping hole in the side of the radiator then I can't use the heating system at all because it'll be spewing steam everywhere. So I'm carefully trying to manage and assess the risk of a half functioning system bird in hand....versus the risk of a totally broken system If the vent breaks. I'm also trying to determine if I'm qualified to do this repair or if I need to call a shop to do it who has proper tap and die experience. It's all about knowing what to do when s*** go sideways.

I have no idea when these vents were last replaced. One of them is painted over with caked on paint. They don't look new at all. The main vent is been encased inside the ceiling of the basement. I think the last owners were clueless and had no idea how to maintain a steam system besides having a tech do the annual service (whatever that I means).

mattmia2

Brass to steel or iron connections tend to not seize.

EdTheHeaterMan

@CoachBoilermaker said: I'm assuming if they're vent cracks off and leaves a gaping hole in the side of the radiator then I can't use the heating system at all because it'll be spewing steam everywhere. So I'm carefully trying to manage and assess the risk of a half functioning system bird in hand....versus the risk of a totally broken system If the vent breaks. I'm also trying to determine if I'm qualified to do this repair or if I need to call a shop to do it who has proper tap and die experience. It's all about knowing what to do when s*** go sideways.

Actually you could keep operating that system, by turning that radiator off at the inlet valve. You could also stuff the vent hole with a wooden peg as a temporary stop gap measure. But I applaud your efforts to know everything that could go wrong and try to prepare for it.

Long Beach Ed

Third week of October isn't an ideal vent-wrenching week. But the vast majority of vents unscrew without any drama. As Matt says, brass seldom seizes to iron. Check your angle valve, and have any it. I've unscrewed thousands of these and never broke one off. I have drilled and tapped radiators too and that's not too hard either. The iron's usually old great quality that takes threading beautifully.

Big Ed_4

If the vent is removed ,running a 1/8" NPT tap is good practice to clean the threads before installing a new vent , If the stem breaks in the radiator, I find it best to first drill it out with the drill size marked on the tap , then clean it with the tap … I don't recommend using easy outs , not on cast ….

CoachBoilermaker

https://forum.heatinghelp.com/discussion/comment/1814469#Comment_1814469

The inlet valves are possibly 100 years old, and I have no idea if they work. I tried turning one of them and had zero confidence it was not going to fall apart in my hands (while simultaneously feeling stuck and catchy)

I do not own any wood pegs, nor do I know where to buy one. Home Depot?