steam valve location on a radiator

pookeye

Hello, sorry for my ignorance here, I am trying to understand where the steam valve should come out, should it come out on the top on the otherside of the supply? or should it be in the middle on the other side.

also if its meant to be in the middle, how does one get the one screw out, so we can put a 1/8 steam valve there, been spraying PB blaster, but not quite sure how to remove it, since it seems stuck there.

also I have a steam radiator that has a hole that is bigger than the 1/8, I want to open the hole large enough to add a reducer, but I need to know what type of drill will be needed to drill in cast iron, should it be carbide? and do they have said product at home depot?

thanks

EBEBRATT-Ed

The vent with the hole you will have to drill it out with a 7/16" drill bit and a 1/4" pipe tap then put a 1/4 x 1/8 reducing bushing on it with your vent.

A regular drill bit (high speed steel) is ok

The first radator I would locate the vent where the tapping is. Why do you want to move it?

pookeye

its two issues.

1.) i had one where the hole is too big for 1/8 but too small for 1/4, so i'll do as you say and drill with 7/16 and add taping.

2.) I have a few radiators that had the steam vent where the plug is on top (I think they were water radiators (thin fins) but from what i understand the steam vent SHOULD be located in the middle or near the bottom.

so i need to know what size drill bit will work to tap a 1/8" tap.

so there is no moving it, just two different radiators with two different problems.

Hap_Hazzard

pookeye said:

so i need to know what size drill bit will work to tap a 1/8" tap.

For 1/8" 27 NPT you should use a Q, but if you don't have letter sizes, use 21/64" and ream it a little with a taper reamer if you need to in order to get the tap started.

I'm attaching a copy of Irwin's metal drilling guide you can print out. Pipe taps are on page 3.

Neild5

Some of the old radiators had a fake screw head cast where the vent goes, you still need to drill and tap it.

pookeye

is there any reason why its in the middle or the top, like any benefits to having it in the middle vs the one on the top?

Hap_Hazzard

Yes. Because steam rises, it reaches the top of the last section before it finishes filling across the bottom. If it stopped venting at that point, less air would be vented.

Fred

pookeye said:

is there any reason why its in the middle or the top, like any benefits to having it in the middle vs the one on the top?

The tapping on the top is to bleed air out of the radiator when it is on a Hot Water system. The middle tapping is for a steam vent. If you use the top tapping on a steam system, the steam will travel across the top and close the vent before all the air has been vented. For a steam system, use the middle tapping.

pookeye

thank you @fred, that is the information i wanted to confirm.