Radiator Supply Valve - Why do we need 'em?

ConservationCrowley

Hi All,

I know enough from the Holohan books that if it would work fine, the Dead Men would have done it that way to begin with, but my question is: If I'm leaving my radiator supply valves open all the time, do I really even need them?

In my 1-pipe residential system I had recently decided to replace a leaky valve with a tee so I could vent the riser as shown in the photo below. The photo (courtesy of Greening Steam) shows an in-line supply valve, but I am curious as if or why I would need a supply valve at all?

Thank you to any and all Wallies who can answer my seemingly simple question. I've been losing sleep lately trying to figure it out on my own! What is the purpose of the supply valve and when/why would I ever want to close them?

SlamDunk

You sure do. If your radiator leaked or was failing in any other way, you would want to shut it off. A maintenance feature. I saw a vent pop off once and turned the room into a sauna in seconds.

ethicalpaul

The pressure must have been running pretty high to pop off the vent and then turn the room into a sauna!

So many valves in the wild are broken I think the need for the valve is extremely minimal.

But the normal valve gives:
1. An elbow
2. A union 
3. A valve
4. in a compact package
5. For a good price

in your case put the valve in since it doesn’t hurt and it gives a bit of utility. But if you needed to not have one due to space or something I wouldn’t lose any sleep about it

SlamDunk

It wasnt installed properly. Less than 2#'s

ethicalpaul

Less than 2psi turned a room into a sauna in seconds from a 1/8” vent port? 🤔 I’m skeptical but there’s so much I haven’t seen! 

gerry gill

It mattered more with a constant firing coal boiler than it does with a gas or oil boiler that has a power switch.

SlamDunk

ethicalpaul said:

Less than 2psi turned a room into a sauna in seconds from a 1/8” vent port? 🤔 I’m skeptical but there’s so much I haven’t seen! 

Easy enough to test in your own home.

1600:1 ratio of steam to water.

ethicalpaul

I think I have tested it 😂

1600:1 ratio argues in my favor I think! Even a lot of steam becomes very little water when it hits the cold room air

I might test it for real, I’ll let you know

ConservationCrowley

Thanks all for your help and words of wisdom.

My take-away is that though you don't "need" the radiator supply valves... you will need them when you need them!

I'll do as @ethicalpaul suggests and put in the valve for utility and for the sake of the next poor sap who lives here when I'm gone.

FWIW: last winter we ran almost all the upstairs radiators w/o radiator vents (wide open) because we didn't have the ability to vent the mains/dry returns/etc. Never did a room turn into a sauna

Grallert

Not to state the obvious but if you didn't get steam pouring out of the vent holes on the second floor radiators that means the boiler shut off before steam was able to reach those rads. Likely the thermostat satisfied in a nick of time. Could be an issue if for some reason the boiler continued to run.

ethicalpaul

Yeah, running with no vent on a radiator isn't good practice

But steam might have met that radiator and condensed while heating the first sections--seems that at some point during the winter it would have made it to the open vent port though! So something might be weird.

Intplm.

ethicalpaul said:

I think I have tested it 😂

1600:1 ratio argues in my favor I think! Even a lot of steam becomes very little water when it hits the cold room air

I might test it for real, I’ll let you know

Just take @SlamDunk word for it. Otherwise you could be in for one hell of a mess.

SlamDunk

I wouldn't lie. The vent suddenly popped off while boiler was firing. The steam condensed on every wall, floor, every surface, even the ceiling.

Steam will take the path of least resistance and you aren't just depressurizing the rad- you are depressurizing the entire system.

So, if you don't have a valve, you have to wait until all the steam has escaped. And that is whatever pound(s) for every square inch of the system.

ethicalpaul

I believe it happened, but there's a lot to unpack here. I'll try it, but don't hate me, I just love the topic!

It would have had to have been running from a long setback or something, because the entire system would have had to have been fully hot--every radiator full, every vent closed.

If not, then the system wouldn't be at or near 2psi. And once the vent popped off, there would still be other avenues for the steam to go. The entire system's steam wouldn't all go to the vent port--it would be condensing in each radiator (which it would also be doing even if the system was fully hot). It's not true that all the steam in the system will exit that port.

Once it popped off, it's an easy trip to the boiler kill switch. The boiler stops creating steam pressure almost instantly.

Now let's look at the after effects: condensation on every surface. How long was this system running with the vent popped off? It must have been quite some time for every surface to get covered in condensation. And if there's no one there to see the steam filling the room, there's no one there to turn off the valve, either

Finally, how many were killed due to this perfect storm?

STEAM DOCTOR

My mother knows someone who was babysitting for her niece in. NYC apartment building. Radiator wasn't getting hot. Young lady correctly diagnosed a clogged air vent. She removed the air vent, put the baby in for a nap and closed the door. The poor baby suffocated to death. @DanHolohan has a write up about that very sad story. 

ethicalpaul

That is a horrible story, that would be unchanged regardless of the presence of a valve, which is the point of this discussion.

SlamDunk

How long? Not long.
We just installed a new pressuretrol and were waiting to see it cut out and cut in. At some point, while in the basement, we heard the vent pop off. So, in the time it took from the sound to realizing this is a problem, to running to the second floor to see the genie, just minutes. The damage was done. We wrapped a towel around the hole; we didn't have a valve so we had to let it bleed out. And, the boiler was turned off while heading up. It was a vertical pipe with a vent at the top. We installed the vent too, so we kinda new what the noise was.
The point is, valves are for maintenance.

As for how many were killed? no one. but It could have.

https://www.ny1.com/nyc/all-boroughs/news/2017/12/16/scylee-and-ibanez-ambrose-parents-suing-nyc-for-radiator-explosion-bronx

ethicalpaul

I don't know if that's the same story or a different one, and yes, it's horrible, but unrelated to the value of a radiator valve. But anyway, yes, install valves. But I don't think we have to try to make it be life or death...it isn't.

SlamDunk

@ethicalpaul, you asked how many were killed in this perfect storm, as if noone can be killed. You also poopoo'd my story of how a vent turned a kitchen into a suana.

My original point was to keep a valve for maintenance. Secondary, in case of emergency.

Not trying to kill you, just feeding your love of the topic.

LS123

based on my experience I would keep the valve.... recently I tried to get something (expensive Iphone that got stuck between the radiator) I tried to move the radiator a little bit (mind my house is steam, everything is original, radiator came off the connection. If I didn't have a valve, I wouldn't be able to able heat the rest of the house with steam radiators.... if the valve was not there, I would have had to call for heating contractor for emergency repair.... right now i am not in a rush since I have two other radiators in living space.... so please keep the valve....

LS123

I mean everything is old, over 70 years. I suppose, unless there is another way to control steam going in to each radiator, valves been around for a while for a good reason. In my case, I may need to get a very little steam leak fixed (once in a while I hear hissing sound other than steam valve) steam leak seems to be from joints that connects each radiator component to the other. because of the valves being available, I dont need to stop heating my whole house.... hope you stick with control valves...

Big Ed_4

The only way to shut off a one pipe steam radiator is to plug the vent .

LS123

thanks @Big Ed_4

motoguy128

Radiator valves have a union attached. If you are going to go through all the trouble of installing a Tee, a union, a bushing or plug and two pipe nipples, why not just buy a new radiator valve. Probably about the same price.

bburd

Radiator shutoff valves are required by most mechanical codes. If you take them out, be prepared for the next buyer’s home inspector to flag this as a defect.

mattmia2

ethicalpaul said:

I think I have tested it 😂

1600:1 ratio argues in my favor I think! Even a lot of steam becomes very little water when it hits the cold room air

I might test it for real, I’ll let you know

The bigger danger is asphyxiation when you displace the air in the room or burns in your lungs.

Jamie Hall

Two comments.

Well, three.

First, on some steam systems the inlet valves are integral and essential part of the system for controlling steam flow to the radiator. Virtually all vapour systems. And they can be used for control and balance on any two pipe system.

Second, a valve is a very handy and simple way to cut off part of a system when maintenance is needed on the another part of the system. They are not expensive, and the craftsman who fails to put one in where needed is doing no service either to the operator/owner of the system or to the poor soul who has to maintain the system down the line. How many times have we had to tell some poor soul that he has to drain his whole system because some cheapskate didn't put a shutoff valve on a feed line?

As a sort of general rule, if you have a widget of some sort which may need maintenance, but which the rest of a system (I don't care if it's domestic water, hot water heat, steam, whatever) can operate without while maintenance is performed on the widget, put in an isolation valve. The cost of the valve will be saved the next time you need to work on the widget.

EBEBRATT-Ed

Not necessary IMHO. All you have to do is shut the boiler down as mentioned in @gerry gill old post above.

If you have a leaking radiator etc. shut the boiler off disconnect it and cap the pipe(s). I doubt it's a code issue.

90% of the old valve won't shut tight anyhow. That's for a single family home and apartment or condo or multiple tennants and they don't have access to the boiler room or a way to shut the heat down that's another story

jhewings

@ConservationCrowley I did my riser vents like the photo below. Your valve is leaking so I guess you have to change it (including the spud)
. Still, this method does not push the radiator to the left, which might not be possible anyway. Also you can vent your other risers this way too. I have 4 risers and I thought I should vent them all.