Steam boiler fact checks

bdsaintess · 1:02AM

Hello, I'm trying to better understand how steam heating systems work, specifically at the component level, and I'd appreciate any insight.

I'm in a 19-unit condo with a steam boiler. We were recently advised to replace radiator valves and air vents that simply appear old, despite being in perfect working order. To justify this, we were provided the following explanation:

"The system heats water to create steam, which circulates through the building for heating before condensing back to water and returning to the boiler. Vents release trapped air and enable steam to flow efficiently and safely throughout the building — without proper venting, entire tiers can experience heating issues. Valves regulate pressure, control the flow of steam, and prevent backflow. They are essential to maintaining system balance, protecting equipment, and ensuring stable operation."

Based on my research, I believe this description conflates system-level functions with individual radiator components, and I'm hoping someone can either confirm my understanding or point out where I'm wrong.

Specifically:

- Radiator shutoff valves appear to be simple on/off valves. Pressure regulation is handled by pressure controls at the boiler itself, not at individual radiators.

- Backflow prevention doesn't seem applicable at the radiator level — steam flows in one direction, and system balance is managed through main vents and boiler controls, not individual radiator valves.

- Main air vents (located on the steam mains) affect large sections of the building. Individual radiator vents only release air from that specific radiator. A failed radiator vent means that radiator won't heat well — but it shouldn't affect other units.

- Pipe pitch issues cause condensate to pool locally, potentially creating water hammer in that radiator. They don't appear to affect the boiler or other radiators.

In short, my understanding is that individual radiator component condition — vents, valves, pitch — affects comfort in that unit, but not overall boiler operation or building-wide heating.

Is this accurate? Am I missing something that would explain how individual radiator components have the broader system impact being described?

mattmia2 · 1:27AM

more or less.

if a valve is stuck partially closed it can cause a radiator to trap condensate which can be a issue

if too many radiator valves are stuck or broken closed or too many radiator vents are failed closed they will cause there to not be enough radiation o absorb the amount of steam produced by the boiler and it will short cycle.

failed open vents will cause loss of water from the system in the form of steam which will cause much more corrosion in the system as makeup water is added to replace it.

leaks in valve packings will also cause water loss but in most cases it is better to rebuild or repair the existing valve than to replace it if it has a leaking packing or worn washer or washer that has become unscrewed

pitch of the mains or runouts to radiators may be outside of the unit they serve and may cause the radiators they serve to not heat or bang, depending on where it is it could affect many units

there are ways that individual radiators can affect the whole system in a 1 pipe system but it isn't as pronounced as what a failed open steam trap or incorrectly adjusted vapor valve can do in a 2 pipe system.

the valves in a 1 pipe system need to be coordinated to balance the system, some radiators need faster venting than others based on proximity to the boiler and radiator size and changing the vent rate of one vent affects all the other radiators too

Alan (California Radiant) Forbes · 1:28AM

Yeah, I think they are trying to look smart. They should have consulted with you first as you know more than they do.

Steamhead · 4:06AM

@bdsaintess , where are you located? We might know someone near you who actually does know steam………..

109A_5 · 4:32AM

If your old vents work correctly (vent the air and not leaking steam) and you can balance the system I'd leave them. I think the old ones are better quality than the new stuff. Most of mine are at least 50 years old.

bdsaintess · 2:43PM

https://forum.heatinghelp.com/discussion/comment/1892905#Comment_1892905

I'm in Chicago!

bdsaintess · 2:49PM

We've been told the boiler is in perfect working condition and our gas bills are the lowest they've ever been. That would signal to me that everything is fine but again, we're being led to believe an older valve simply based on age that isn't leaking should be upgraded. I've had a consult with an HVAC company and they said it would not be their recommendation to replace anything that works and isn't leaking, but they wouldn't put it in writing which my board wanted. I would absolutely fix something the second it was not working, but I'm smart enough to know that replacing a valve doesn't also equal it couldn't fail in a month.

Plus! Older stuff is so much more reliable!!

Jamie Hall · 2:54PM

Good luck. You are absolutely correct that replacing something old which is working properly — as you seem to have — is … um… trying to be nice here… STUPID. Convincing a board full of modern up to date whiz kids of this isn't going to be easy.

You say Chicago? See if you can get in touch with @The Steam Whisperer and see if he can lend you a hand.

mattmia2 · 3:01PM

i was trying to remember who is in chicago. @The Steam Whisperer is the one to go to in chicago.

mattmia2 · 3:15PM

there probably should be some bigger control of the individual radiators by the condo board, like they maintain them and you have to go through their contractor to change anything and it is subject to feasibility. it sounds like they have a contractor that knows what they are doing but it got lost in translation through the condo board

JohnNY · 3:22PM

I feel like this is written by a plumber (not that there's anything wrong with that). Words like "circulates" and "backflow" do not appear in my steam evaluations because they have direct relevance to other mechanical systems.

Some of the rest of the verbiage, I want to say is simplified for clarity, which is something we sometimes have to do for a co-op board, but this stuff is just wrong. Good luck getting that straightened out.

109A_5 · 3:26PM

So the board would want a contractor to sign off on all the water pipes in the building (that are not new) that don't leak and function properly ? Sound like they have too much time on their hands.

ethicalpaul · 4:21PM

Reads like AI to me

Steamhead · 5:15PM

https://forum.heatinghelp.com/discussion/comment/1892925#Comment_1892925

https://forum.heatinghelp.com/discussion/comment/1892926#Comment_1892926

This!

dabrakeman · 7:35PM

I have 13 radiators in my house. 9 of them have the same vents on them that were there when I bought the place 24 years ago. Of the 4 I replaced (one because of a new radiator and another was due to wanting a slower vent) three failed and had to be replaced again. I have 12 valves that appear to me to be original to the system. I certainly would lean toward "if it ain't broke don't fix it". For the vents it seems to be a risk with some of the newer vents having questionable quality. For the valves it seems like quite an expenditure for a 19 unit building if there is no reason to be changing them.

bdsaintess · 8:02PM

https://forum.heatinghelp.com/discussion/comment/1892927#Comment_1892927

It's certainly an interesting situation. I own the radiators and an fully responsible for them since they only serve my unit. The association can't only control repairs if they impact the overall system. I honestly believe the board was misled by the management company and they think they're doing a good thing for the system by forcing everything to be updated, even if it's working just fine.

Steam boiler fact checks

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