1/8th Inch Air Vent -- Just won't go into hole?

heatinghorse

I have a 1950's steam radiator system, with adjustable air vents on each radiator. I tried to replace the air vents, and I just cannot get the new ones into the holes--it's as if the hole was intended for a just slightly smaller screw. I.e. it's not that the threads won't catch, I can't get it in at all. The old screws seem to have been "crushed" so as to fit in.

Any ideas?

BobC

Sometimes a run of Vents gets out the door with British rather than NPT threads because the wrong die is used. The difference is the NPT's are tapered.

Get yourself a 1/8" NPT tap and the hardware store and see how that goes. Just don't go hod wild with it because if you go to far you could end up wuth a slightly larger hole than you want.

Bob

heatinghorse

Thanks,

I think I'll probably call a plumber in for that. I'm afraid I'll end up having to replace a radiator if I mess it up.

Why don't I just buy a British vent and see how that goes?

Steamhead

There really are no British vents. What @BobC was saying is that in some cases the threads on the vents weren't cut properly, and don't have the proper taper.

But it's much more likely the hole in the radiator just needs the threads cleaned out, and a tap will do this. Just make sure you don't overdo it- only tap as much as is needed to get the vent to thread in.

NPT= National Pipe Thread, the standard used in the USA.

heatinghorse

Got it. I do have a handheld 1/8th inch tap, which I'll try.

If I do make the whole too big--then what? Can it be cut even larger so that a larger vent fits? I don't want to ruin a radiator.

Fred

If you make the hole to large, which I doubt you will, the next step is to have the radiator tapped to accept a 1/4" bushing and bush it back down to a 1/8" hole.

heatinghorse

Thanks, all, I'll give it a try and report.

Pumpguy

Make sure the tap you have is a 1/8" NPT. It's much bigger than 1/8" in diameter. The drill size to make the hole for this tap is 11/32" (0.344"). It would also be a good idea to run your vents into a 1/8" NPT threading die to clean up their threads.

As mentioned above, keep in mind that these threads are tapered. Running the tap in too deep, or running the vent too deep into the die will result over or undersize threads, which then won't tighten up properly.

heatinghorse

Ok, I got one. Still having a really hard time getting the tap the others.

heatinghorse

Why don't I just take an adjustable die, and make my vents slightly smaller?

Big Ed_4

Always clean the threads with an NPT tap ... No oil

Pumpguy

@heatinghorse, I don't believe 1/8" NPT threading dies are available as adjustable types. Being tapered, it depends on how deep or how shallow you run the die on as to how large or small the resulting threaded diameter will be.

As far as cutting lubricants go, when I worked in machine shops, we used kerosene for tapping cast iron. When cleaning up the male threads on the vents, this will depend on what material they are made from. A few drops of cutting oil from the hardware store will probably work as good as anything.

When you're finished cleaning up the threads, be sure to degrease with a solvent like acetone or similar. You don't want any oils getting into your steam system.

Shalom

Pumpguy said:

The drill size to make the hole for this tap is 11/32" (0.344").

Technically it's a size Q drill, which is 0.332", but I don't know anyone with one of those in his toolbox.

ChrisJ

Shalom said:

Pumpguy said:

The drill size to make the hole for this tap is 11/32" (0.344").

Technically it's a size Q drill, which is 0.332", but I don't know anyone with one of those in his toolbox.

I have about 20 of them.

BobC

@ChrisJ Seems a bit excessive.

Bob

ChrisJ

BobC said:

@ChrisJ Seems a bit excessive.

Bob

I work in a machine shop now.
I mean, sure I do a lot of others things that are excessive, but, the drill bits have an excuse.

BobC

I figured you were trying ti corner the market!

Bob

Big Ed_4

Normally you would use oil , but you don't want to get oil in the system . If you do , you would need to skim the system.. Since we are just cleaning up the threads , I clean them dry...

heatinghorse

I had a heating servicer come and re-tap the air vent holes for me. Took them 10 minutes for all three, charged me $350 (I supplied the air vents).

Seems a bit steep, huh?

(Got the reference off this site if that matters)

Fred

We tried to convince you to do it yourself. There is a price to be paid for being afraid to give it a try.

ChrisJ

We don't discuss pricing here but to be fair, I'm sure there's travel time etc. There's no way he was out of the shop for 10 minutes.

That and skill is worth something as well.

heatinghorse

Ok, still, let's assume 99 dollars to come out. They'd already been out the day before for the diagnostic. There were no materials--how much can the hourly be?

Fred

heatinghorse said:

Ok, still, let's assume 99 dollars to come out. They'd already been out the day before for the diagnostic. There were no materials--how much can the hourly be?

Maybe about $251.00 with a one hour minimum. I feel your pain but there isn't much you can do about it, at this point. I'm sure the invoice details the charges and any minimums. There is travel time, overhead costs, trucks, tools, rent, insurance, utilities, salaries, cleaning materials, inventory, depreciation, medical coverages, fuel for the vehicles, telephone charges, admin fees, billing/accounting fees, federal, state and local income taxes, license fees, periodic training, a reasonable profit, even a factor for non productive/non billable time, other stuff that has to be included in their charges.

JUGHNE

And then I have had "10 minute" jobs where everything went south....such as the pipe tap snaps off....or the hole is too oversized to retap, so drill and tap to 1/4", add bushing etc.

However, these numbers should be good incentive for people to consider going into the trades.

Although the worker maybe only got 1/2 of the hourly amount you paid for (which included his bennies), he should be able to make the boat payments.

There is the joke goes with the Doctor complaining about what the plumber/heating person charges. "I'm a brain surgeon and I don't make that much money"......the plumber replies "yea, when I was a brain surgeon I didn't make this much money either"