Cross Threaded Air Vent?

hwangnyc

I've been having an issue with an air vent, see previous post (http://forum.heatinghelp.com/discussion/153967/does-this-vent-need-replacing#latest). I decided that it needs replacing. When I looked at it in more detail today, it appears that the vent has been cross threaded on (see pictures). In the event it is cross threaded on, what is the next step? Take a 1/8 tap and try to clean out the threads? Any advice would be greatly appreciated. Thanks!

ChrisJ

I would use a tap and chase the threads. If it ends up too loose I'd then drill it out and tap it for 1/4" and install a 1/4" to 1/8" bushing. These are available nickel plated which looks nice.

I'm not 100% sure, but I want to say a 7/16" drill bit is used with a 1/4" NPT tap. I know size Q is for 1/8" but not 100% sure on 1/4".

Fred

I'm not even sure it is cross threaded. It looks to me that maybe only about 1 (at most 2) of the vent threads are screwed into the radiator. Before I did any tapping, I would just try to screw the new vent in slowly.

hwangnyc

Good point Fred, Thanks for the advice Chris!

Do you think it would be good idea to try and screw in a 1/8 screw in slowly to "clean" the threads?

ChrisJ

1/8" screw isn't the same as 1/8" NPT.

I used a 1/8" tap to clean the threads on all of my radiators. Just start it carefully and run it in slowly by hand going little bits at a time and don't go too tight. This will clean the threads without cutting them deeper. It turns pretty hard when cutting threads.

Fred

If you have a small pick set, you can run it along the first 2 or 3 threads in the radiator. I have a set that is made by Husky and there is one that is angled and works great for just runing along threads and cleaning out any junk. Otherwise, do as Chris says and go slow.
EDIT: I might add that I had a couple radiators in my house that had vent ports that were an odd size (very slightly smaller that the current 1/8" vent stem). That was an easy fix by just running a 1/8" tap into the hole. Very little resistance but enough that the vent would not screw into the hole more than a thread deep, similar to your pic.

JUGHNE

You might buy a 1/8" x 4" black nipple, try this in the threads before chancing damaging the soft brass male threads of a new vent. If you bought an 1/8 tee, you could make a handle also for this thread cleaning.

ChrisL

Adding on to using a 1/8 pipe, you can take a hacksaw and cut one or two slots in it to allow debris a place to go if the threads are really bad.

ChrisL

hwangnyc

Hi All, I ended up buying a 1/8 NPT tap. I was unable to get my new vent to go more than 1 full turn, so I ran the tap slowly and gently cleaned the threads until I could get the new vent in. I'll post a picture shortly! Thanks for your help all!

Fred

Great!