another stupid question re TRV install

Jim Cheung_3

Photo below is of the part of the TRV assembly that screws into the radiator---it's the male part of the union. My amateur question is, how do I tighten it into the radiator? A Pipe wrench will damage the thread, there's not enough unthreaded space.

There are two lengthwise ridges on the INSIDE (one is barely visible in photo). Is there a tool that tightens from the inside using these ridges?

Can I just leave the existing piece of the manual valve I'm replacing? This would be the simplest thing. Is this a bad thing to do? Are the threads on the valve side going to be different on the TRV compared to the old manual valve?

Many thanks,

Brad White_17

Spud Wrench

Another tool you did not think you needed!

No dumb question at all. I ruined a few before I asked. ("the only dumb question is the one you did not ask", was sage advice to me years ago. But this does NOT apply to asking for directions, for we are MEN! )

Spud Wrench: Sometimes goes by other names. This tool looks like a tapered mandrel (no, not the baboon-like creature).

It is a rod of iron tapered in steps to suit various sizes. One wrench will serve about four or five sizes, probably all you need.

Along the length of each stepped section are grooves cut in on opposite sides which receive the ridges or bars you are describing. The tool is inserted into the union tailpiece once it is doped and turned in hand-tight into the tapping.

The end of the wrench is hexagonal and is turned by any monkey or stillson wrench or a T-handle wrench made for the purpose. Go easy! It is too easy to over-torque and crack a cast iron radiator. The brass is softer and small diameter so that is a help. Chances are the bushing you use, if any, will be more critical if of iron.

Tool can be bought at any plumbing supply house. Mine cost about $15 and that was about ten years ago.

Once you have one you will be a hit at parties and your social life will never be quite the same.

As to leaving the old tail piece? No, I would not. Even if it seems to fit, the valve unions are ground to close tolerances. If not so perfect you will be tightening it (under pressure with a leak too often) and ruin one or another part.

By the way, I like to use Macon valves and these have a 12 or 13 mm (I believe) Allen/hex wrench for instertion. Very positive, no slip installation.

Hope this helps.

Brad

Jim Cheung_4

OK, thanks! I am glad I did not discover this after draining the system in this cold weather. I will look for this tool (I hope it is a Home Depot or local hardware store type item).

PS It is a Danfoss, brass fitting, not cast iron.

Brad White_9

Yes definitely brass

from the photograph. Just stating a cautionary note on that point not to go overboard on tightening regardless. HD does carry the wrenches but not all of them do. One place to try if more convenient. Have fun!

Brad

Steve D._4

I was SOL with HD and Lowes. Plumbing supply had one for $15.

You will also want a large crescent wrench.

Steve

Mike T., Swampeast MO

When installing you can often find things in the tool box that will work instead of a true spud wrench. Use a decent amount of teflon-containing pipe dope on the tailpiece (keeping it 2-3 threads away from the very end). The pipe dope lubricates nicely and it takes surprisingly little torque to make up those joints.

R. Kalia_8

> When installing you can often find things in the

> tool box that will work instead of a true spud

> wrench.


More likely for your toolbox...I'm an amateur!

Anyway, I've ordered the spud wrench by mail. (I knew the word "spud wrench", but it means about six different things; I didn't realize before this thread that there was a specific type of spud wrench for this application.)

Many thanks to everyone who replied!

Brad White_9

In Idaho and Maine

a spud wrench will get you something entirely different!

John Van Hoesen

Crescent Wrench

I used the handle of a crescent wrench for my first couple until I got a spud wrench... ha ha ha...

J~