Is it okay to drill a hole for a 3/8 pipe?

Mike Cascio

I sucessfully drilled and tapped the 3/8 hole on the bottom of the concentric reducer. About a gallon of water came out of that hole. I then put a 3/8 pipe plug in the hole until the returns are changed over. After firing up the system with all of that water out I heard about 70% less water hammer and the last radiator off of the main heated up about 20 times quicker that it normally does. Also the main vent worked for the first time, normally it is flooded. I think I am going to see a big difference when everything is changed over.

Thanks for all of your help,
Michael J. Cascio

Mike Cascio

Hi,

I am in the process of getting our steam system into shape. The plumber is coming in the next few weeks to replace the 81 year old near boiler wet return pipes. While this is happening I am going to change back to the wet return style for the large main of the house. There is simply not enough vertical height to have a dry return, especially since it is a finished basement. Then there is a concentric reducing tee right before the end of the main that is 2in IN 1 1/2 TOP and 1 1/2 OUT. I know that water builds up before the 1 1/2 pipe so I would like to put a drip line before the fitting and tap it into the wet return. Is it okay to drill and tap a hole for a 3/8 iron pipe to fit in? What size drill and what size tap do i have to use with 3/8 pipe? Ironically this fitting is original to the system. I dont know why the steam fitter would have installed a fitting like this to a parallel flow system. With the change to the wet return and the drip line attached I think the system will run quiet for the first time.

Thank you all for your help,
Michael J. Cascio

Steamhead (in transit)

Why not

have the plumber change that tee to 2" in, 2" out and 1-1/2" top? Then you can run your new return right off this tee, and you don't have to worry about a 3/8" drip line plugging up.

Mike Cascio

There are two more run offs after this tee.

MIchael J. Cascio

Steamhead (in transit)

The right way

would be to change the tees and have the 2-inch continue past the last rad runout connection, and add a proper main vent connection at the same time. This is the ideal time to do it since you'll have the return disconnected. You'd have to have your plumber put a union in each runout where you replaced the tees, but that's not as hard as it looks. This is one case where a Dead Man screwed up.

I know this will cost more money to accomplish, but it will work much better.

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Mike Cascio

I figured that would be the correct fix. But since it is my grandmothers house and she has only so much money to fix the near boiler return lines, she wont opt to spending the extra money on repiping the last three run offs. She thinks that since it is steam its supposed to make noise. At least changing back to the wet return fashion and adding the 3/8 line before the run off would have the system drain dry after the boiler cycle. This is certainly something that it doesnt do right now. There problably is more than a gallon of water sitting in these pipes at all times. This produces some very memorable noises when the system starts up. And to top things off, the main vents are always flodded shut. So in order to get the system working somewhat better, this was my idea that wouldnt cost anything extra. So if this is the case what size drill and tap would be nessecary to install a 3/8 black pipe. I will be installing a couple of unions so I could clean them at a future date.

Thank you for all you help, maybe someday when there is extra money I will convince her to change that to 2 in runoffs. At this time I am lucky enough to convince her to change back to the wet return.

Thank you,
Michael J. Cascio

Tony Conner_2

You Need...

... a 19/32" drill and, of course, a 3/8" NPT tap. You do realize that the pipe wall you're drilling will not likely be anywhere near as thick as a 3/8" pipe fitting is tapped, right? The nipple will stick through the pipe wall by a good bit, and the water below that piece won't drain. I'm not sure that this is going to achieve what you're hoping for.

Steamhead (in transit)

Well, then

the place you want to drill is the bottom of that reducing tee, at the point where the reduction actually occurs- the actual surface of the tee changes to roughly a 45-degree angle relative to the pipe at this point. This will give you more wall thickness to work with, and the nipple won't stick up so far inside the tee.

Drill it out for 1/2" pipe if you have the room, the larger size will resist clogging better. As the pipe leaves the tee, enlarge it to 3/4" as soon as you can, and as you say, leave a union or some form of access so you can clear the 1/2-inch portion if needed.

Pipe the 3/4" line below the water level before tying into the wet return. This will prevent banging.

I'd suggest your plumber do this, while he is replacing the return.

"Steamhead"

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Tony Conner_2

It Can't...

... be much more work to just re-pipe this properly, can it? Not many guys are packing drill bits in this size range, and not many more have pipe taps. Everybody has pipe wrenches and Sawzalls.

bob young

weldolet

for a quick fix that will probably solve the problem consider having a welder provide a threadolet to the bottom of the main low spot.

Mike Cascio