WHAT SIZE TAP FOR 1/8\" STEAM VENT HOLE?

RICK LAIN

WHAT SIZE TAP SHOULD I USE TO ACCOMODATE THE INSTALLATION OF NEW MAID O' MIST STEAM VENTS WITH 1/8" THREADED NIPPLE?
NONE OF THE RADIATORS WILL ACCEPT THE STEMS.
IS TAPPING THE ONLY OPTION? THANKS

Andy Morgan_2

Tap

You need an 1/8" NPT pipe tap and maybe a drill bit. Usually, Home Cheapo has a tap and drill as a set. If there is already a hole, just run the tap into it very carefully, cast iron is very brittle.

Good Luck

Andy Morgan

R. Morgan Mechanical, LLC

DaveF

1/8 in pipe tap.

[I am not a professional]

I had the same problem. I bought a 1/8 NPT tap from Sears. This is sold separately from the straight "machine" type taps. I used it to gently remove rust from the existing holes. The farther in you tap, the larger the hole gets, so be careful.

Kal Row

the standard holes, on most

radiation is 1/8, at least all those, that i have come across, so i suggest that you go to your favorite supply house or the HOME DEsPOT, and get:

1/8" black or galvanized close nipple,
1/8" black or galvanized coupling,
1/8" by 3 inch brass nipple,

use the brass nipple with a little vice-grip to clean the threads in the radiator with WD40 - a tap is too hard, and best left to an experienced user - unless you have another radiator to practice on

- and don’t force anything - user plenty of wd40, and turn back and forth a lot, and keep taking out the nipple, and cleaning the radiators threads with Q-tips

then put in the black nipple with thread compound and then the coupling and then the maid'o'mist (which are great valves) - finger tight only

a good steam system, can fill a house at 40 miles an hour with dry steam at 4 ounces of pressure and maintain it with 2 ounces, if your getting pounds, especially more than 2lbs, then you need to have it looked at


this way you can screw with the valve on the coupling as much as you want without distroying the radiator - provided that you don’t have a space constraint - which would be the case with a covered radiator - in which case, you leave out the nipple/coupling

Bill Nye

Drill size

1/8"-27 NPT , You need a tap drill size "R". Most good hardware stores have drill bits sized in fractions, decimal, and alphabet. You need an "R" or something close. .001 one way or another won't make much difference.

Be careful with the cast iron. It is kind of soft and it is easy to mess up the threads. Then you need a 1/4"-18 NPT tap and a 7/16" bit.

Stew_2

1/8\" hole

Do the vents not fit becouse the there is no hole? or are the threads bad?

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BobC

Bad threads on Maid O Mist Vents

I'm reviving this thread to warn people that the current Maid O Mist radiator vents have the wrong size tap on the stem that is supposed to thread into the radiator.



A Hoffman 1A measures 0.372 at the end of the tapping and 0.387 diameter near the vent body. Three Maid O Mists I measured all measure 0.395 at the end of the tapping and 0.402 near the vent body.



I'm waiting for a 1/8-27 NPT die to come in so I can dress the Maid O Mist threads.



Bob