Typical steam pressure at the convector for a University dorm

spaz

Morning folks. New here.

I have a 17 years of experience with residential HVAC and then 20 years experience at a commercial chiller plant for the U Of I.  But the university auctioned my job away and now I’m a maintenance man at one of their student dorms with about 100 residents. The original building was built in 1912 and then added four additions throughout the years. We are supplying 15 pounds of steam pressure to our convectors and I have been told that’s excessive. Is this true?  

EdTheHeaterMan

YES

You need to provide more information, can you access the boiler room?
The Empire State Building is feeding steam from the basement to the top with about 2 PSI steam pressure
(Why do you ask Two Dogs?)
Are you experiencing any problems with not enough heat in some areas and too much heat in others?

spaz

We get steam from the boiler plant and it’s actually more like 12 pounds.  We also have different processes in the building such as flow rite water heaters and heating coils in the air handlers all using the same steam pressure.   What we’re experiencing is the tenants use the convector steam valves as on off switches. When they get cold they crack it, when they’re warm, they close it.  My opinion the valve should never need to be shut and you should be able to adjust how much heat is in the room with how far the convector valve is open.    

EBEBRATT-Ed

@spaz

The issue is the convectors are one thing. You have a lot of equipment and have no way of knowing what steam pressure the equipment is designed for. You have 2 choices.

1. Find some documentation, drawings, equipment submittals or the original engineer who could tell you

or

2. Lower the pressure until someone complains. Typical for those types of buildings is 5-10 psi.

Commercial steam is different from residential or a straight heating system.

mattmia2

spaz said:

When they get cold they crack it, when they’re warm, they close it.  My opinion the valve should never need to be shut and you should be able to adjust how much heat is in the room with how far the convector valve is open.    

That may be a battle you'll never win unless you can limit the max steam available with the valve all the way open to about the heat loss of the room and then maybe a little for recovery without them knowing you did. In residential systems stops that keep the valve from opening more than a certain amount work but kids in dorms will defeat that. They might even defeat valves with a separate metering valve in them. Either a valve before it enters the room or an orifice plate in the connection has a much higher chance of success. Of course that needs to be calibrated for your supply pressure.

pecmsg

Download and read:
https://www.av8rdas.com/honeywell-gray-manual.html

Are the original design prints available?
Commerical has so many ways of achieving their goals. I've seen HW with manual outdoor reset for convectors.

spaz

Thanks everyone.
I'm not aware of any documentation. I'm sure it exists, but the message I'm getting from management is "this is the way its always been". My leads response when I told him the empire state building feeds steam from bottom to top with 2 PSI was "yeah I watched that fake video"
A energy audit would be in order, but I'll try and convince my supervisor to adjust the steam pressure down slowly until we see problems. I had that ability when I operated the U of I chiller plant years ago, but not any more.
Are there any links that are short and sweet that might help convince management other than this discussion?
Thanks again.

Edit: Flo-rite water heaters operate on 2-15 psi, and guessing the coils in air handlers do as well.

EBEBRATT-Ed

Higher steam pressure can make control valves hunt. I would just lower the pressure 2 lbs at a time until you get complaints. If you had a way to put a pressure gauge at the far end of the most heavily loaded main that would help.

Lower pressure saves ware & tear on traps and control valves. Not that there are not systems designed for high pressure their are but it's a waste of fuel to run higher pressure than you need

The Steam Whisperer

EBEBRATT-Ed said:

Higher steam pressure can make control valves hunt. I would just lower the pressure 2 lbs at a time until you get complaints. If you had a way to put a pressure gauge at the far end of the most heavily loaded main that would help.

Lower pressure saves ware & tear on traps and control valves. Not that there are not systems designed for high pressure their are but it's a waste of fuel to run higher pressure than you need

I'd pick this way to address the issue. It's one way to get around "we've always done it this way". I used that same process for a building up in LaCrosse, WI. Lots of banging. I gradually turned down the pressure on the building and the banging gradually disappeared until I got down to 2 psi. With those higher pressures, you get lots of flash steam banging in the returns.

retiredguy

Here is what I saw when trying to solve problems at any building complex that had numerous additions, many years apart. Each design engineer had his own way of sizing equipment, sometimes based on the amount of money available for that addition. They would also specify the steam pressure required for that addition with no regard for the existing buildings requirements. The building was built and the heating system commissioned. Now, the problems begin.

The way the job should have been laid out is that the design engineer would use the specs for the original building and use those specs for his new building. If he wanted a lower design steam pressure for whatever his reason he could always add a "steam reducing station" for that addition. If you chose to challenge that engineer for his stupid mistake you had to choose your words very carefully since he was the "chosen one". I sometimes forgot that fact and it wasn't pretty.

BobC

I learned discretion was a valuable tool when I was in the army over 50 years ago. A SP5 can tell the major he's wrong but you have to do with discretion. A good officer will begrudgingly accept it, one that is bullheaded or vindictive just has to be left to founder on his own - just make sure you get yourself out of the line of fire first. Sometimes the only thing you can do is follow their orders exactly and hope they see the light before the damn thing blows up.

Bob

EBEBRATT-Ed

@retiredguy

I have not seen an engineer who was wrong and admitted it very often.

I had a steam job once where the customer hired an engineer (who knew nothing about steam) to design it. The engineer knowing, he was over his head called the local Sarco rep to help him, but the Sarco rep was never given the opportunity of looking at the job.


The boss bought all the parts they told him to by (he didn't know steam either. So I get the job to install this. A big steam humidification system with flash tanks, traps, reducing stations you name it.

Long and short they didn't need half the stuff they bought.

I complained to my boss and he called the "engineer" who met me at the job with my two pages of notes on what was wrong.

Every question I asked him he said "I will have to review that"

I finally got the Sarco rep there nice guy and very experienced. I told him I didn't think we needed all that stuff and he agreed and everything worked fine