think I can change this valve without a shutdown?

Mikey_333

Hi everyone.

I have a long term tenant in a small apt I own within a co-op building who just left so I am getting it ready to sell or rent out again. It is in a 6 story brick building, typical for the NYC area built in the 1960s. I kicked the baseboard fin radiator while changing the floor and it started to leak a bit. When I removed some fins to try to put a clamp on it, more leaks developed every fin I removed so the entire baseboard is corroded and needs to be replaced. I got the leaks to stop after using some pipe clamps and rubber.

When I closed the supply and return valves to the baseboard, I think the supply is holding, but the return is very old and does not fully close. I know this because everyday I visit the apartment and when I open the air vent, water spurts out for a couple of seconds, then slows to a dribble.

I want to change the return valve with a new one but do not want to get the building super involved for a shutdown. Do you guys know what kind of pressure is typical in this situation on the return side that backs up into the baseboards? I'm hoping I can quickly spin off the old valve and put on a new one but down know if I am being delusional. I'm a DIY guys with basic plumbing skills, just enough to be confident enough to get myself into trouble.

Attached is a picture of the valve I would want to replace. I would have the new valve on the threaded pipe ready and the new valve's handle is a "T style so I would be able to spin it around without hitting the baseboard. I just don't know how much water to expect. Some guys told me a half gallon at most, and others said it would be full pressure if the circulator pumps are on. I'll have a friend on hand with a shopvac to suck up whatever falls in my pan, but can't risk a flood.

hot_rod

What floor is it on? If there are radiators and pipes above, you have that water and pressure to deal with.

Have you ever done a "flying connection" risky even for the pros.

Watch this video posted on FB

Screenshot 2025-11-17 at 4.43.51 PM.png

STEAM DOCTOR

NOOOOOOOOO! Don't even consider it.

EBEBRATT-Ed

It's always risky.

If you put a wrench on the nipple and the nipple snaps in half, what do you do then?

Since the return valve mostly holds why not put a new valve on the other side of the old valve and leave the old valve in place until next summer when it can be done right. You could connect it with prepress or maybe compression. You new baseboard may need to be a foot or so shorter.

Other than that, I wouldn't do it without a shutdown.

SlamDunk

if it is your building, why dont you turn off the system, drain it below this radiator and replace both valves safely? Otherwise, it looks like flex tape isyour best temporary solution.

mattmia2

you could jam a jet sweat in there but I can't say i recommend that.

STEAM DOCTOR

This is a co-op building. What do you think will happen, if there is water damage to the units below? Search on YouTube for "plumber causes major flood in apartment". The money that you save by not hiring a professional, is very unlikely to be worth it!!!

Mikey_333

I love the video, especially the dirty water. This is exactly why I'm asking. Here is the link if anyone else ones to see it instead of searching.

(4) Video | Facebook

The apartment is on the top floor. Not that I trust it, but Chat GPT insists there is not a lot of pressure in the return branch because of my supply being off and the main branch pipe diameter being larger than my branch which makes it a higher resistant path. Also something about there only being static pressure and not pump pressure. I don't understand any of it enough to be confident about it.

It is not even about saving money on a plumber, I really just want to get it done quickly without the super involved (who can tell the board about the other renovation work I did in the apt). I was probably going to end up buying a pro press machine "just in case" I need it; and if I value my own time at a quarter an hour I probably spent more than a plumber on this already, lol.

But seriously if there is any real risk I'll just wait and call the plumber and coordinate with the building to do a shut down and drain the system down below my floor. Buildings are a real PITA, I need to submit license and insurance info to the management office for anyone that walks through the door and it delays getting anything done.

As an aside I have to say that I've been reading your posts and answers over the years across multiple forums and have seen different you tube videos of you explaining products. I have a real curiosity and respect for the engineering that goes into plumbing systems and enjoy learning about them. I really impressed by your knowledge and enjoy reading your posts.

STEAM DOCTOR

Seems to be steel pipe. ProPress won't work, unless you get special jaws and the more expensive variation of the ProPress machine. And you still need to cut away some pipe and hope that nothing else gets damaged further downline, in the process. Really not a wise idea. And check out the YouTube video, different than the one in the Facebook post

hot_rod

even a gallon of water running down the pipes could cause damage to units below. Is it worth the risk?

Thanks for the link addition!

Mikey_333

thanks for the responses. I guess I have my answer.

I originally was going to put an additional valve like was suggested and just lose a little baseboard but a guy at work told me it looks like the joint on the other side of the valve was brazed not soldered so would be very difficult to get it undone with a regular torch (I didn’t know folks used to braze copper for baseboard heating). Had I done that I would have had a good excuse to buy a jet sweat kit to add to the collection.

I’ll just call a plumber and have the super drain it down a floor and have everything done nice and clean. It is supposed to be warm in NYC Friday so maybe I can get it all scheduled for then. I actually called two plumbers i use when I need to, but I live in Long Island and even though the apartment is less than 10 miles from where they are based neither of them do work in the City. A plumber I used for my mother’s house in NYC refuses to work in coops. My friend’s boiler installer said he would come over and do it but only if the building super closes the valves and drains some of the system so guess I’ll be calling him in the morning.

mattmia2

same pressure in the supply and return though it is lowest at the top of the building

mattmia2

it is probably just soft soldered but if i were to add another valve i would just solder or press it on with a coupler, not try to desolder anything.

mattmia2

i'm not sure that facebook video is real. he's loosening the valve clockwise, there is a ton of water gushing in and the prv can't do that, even emptying the expansion tank doesn't account for that. air wouldn't be able to get in automatic vents fast enough to let that much water out

SlamDunk

There are reasons buildings are a PITA.