Efficiency of Steam System

Prospect_Handy_Man

So I work in an old apartment building in upstate New York. The building was built in 1933 and is a two pipe system that has an old Webster 23 series vent trap and a 23 series return trap. I was wondering about why a couple of things were done. First there appears to be a 2" bypass return line that goes around the vent trap so only the vacuum vent is in use on the top, and the two gate valves on either side of the return trap are closed and appear to have been that way for some time. Should that be that way, and if so, should they just be removed so they don't cause future confusion? Next, the main steam line splits right off the boiler and goes in opposite directions around the edge of the building going to rooms above. The two steam lines meet on the opposite side of the basement and connect into a separate wet return line that only the mains connect to. The question I had for that is should there be any vents or an F+T trap at the end of the seam mains before they go into their wet return. The return for the main lines gets very hot and some parts of the building that are farter away from the boiler take a while for the radiators to get hot. Some parts of the building also have some banging noises when the radiators are heating up. I would appreciate any insight since I am not a steam professional in this industry.

JStar

Webster

http://www.heatinghelp.com/files/articles/1337/320.pdf



Here's some Webster info.



The bypass is necessary to move more condensate back to the boiler than the trap opening can provide.



The steam mains should only join below the water line. When boilers get replaced, the installers often overlook that detail.



Do you have any pictures of the system? Specifically the valve arrangement that concerns you.

Jamie Hall

Possible vents

Do the two legs of the steam main go down separately to the wet return?  They really should; otherwise you have a set up (rather rare) called a ring main.  In any event, it would certainly do no harm and probably a lot of good to have a vent at the end of each of the steam mains.  With dimensions -- length and diameter -- it is not hard to figure out which vent or vent combinations would work best.  The vents should help with the radiators which are a little slow.



Assuming the lines (drips) down to the wet return really do go to a wet return, there is no need for a trap at that location.



As Joe said, though, check your water levels to ensure that that wet return really is wet at that location.  That's important.



It is possible that the banging comes from some water hammer in the mains or runouts.  Since this is an older building, it is quite possible that some settling may have occurred and some of the lines might have sags in them, or even be sloping the wrong way.  It would be worth the effort to go around the system and check that everything slopes to drain somewhere.



Are your steam mains insulated?  They should be...



And the last thought (should be the motto of the site, perhaps!) is -- check your steam pressure.  The boiler cutout should not be over 2 psi, and preferably less -- say 1.5 psi.

Prospect_Handy_Man

Old building

The legs of the steam main do come down separately to the return. I can get some pics tomorrow. I replaced the old rusted out return that the mains connect to last year, but I didn't change anything about it. I have noticed that the water level will fluctuate while the boiler is running about 3 inches on the sight glass. the boiler is relatively new. Unfortunately the sloping portions of the steam risers and the return lines are not visible above the basement level since they are above the plaster ceilings in this building. Still not sure why the return trap gate valves on either side of it have been closed, thus eliminating it from use. The steam main in this building is 4" and the return is 2". Don't know the length. Should the old vacuum vent with the metal marble be replaced with something newer. I'll get some photo's and more info on everything tomorrow. I'll be in the middle of tearing apart a wall to replace a clogged return line (wish me luck). Do I have to replace this return with black iron pipe or can I use pex or copper pipe since the return line is never hot with properly working traps at the radiators. Also the 72 year old man who used to own the building said he took the guts out of some of the radiator traps, so i'll be checking all the traps to make sure that they are still there and working properly.

JStar

Steam

The return trap isn't necessary on systems with modern controls, but we here like to see them left in use to honor the history of our trade. The valves can be opened if nothing is leaking.



All piping should be replaced in black iron, or copper if below the water line. In my opinion, I'd stick with black pipe.



The main vent can be added to or replaced.

Prospect_Handy_Man

Pics of the system

You will see the two old traps here, and the two legs of the main connecting to their wet return that was just replaced. As you can see after the traps, the two wet returns connect to each other and go into the boiler. Their is a smaller water boiler in these pictures as well, just in case it's confusing. the steam boiler is a Weil Mclaine. Much of the main is not insulated, so i'll be sure to do that soon. For some reason I could not post the photo's directly to this site, so here's the direct link to them.



www.heatinghelp.shutterfly.com

Prospect_Handy_Man

System pressure

I looked at the Pressuretrol on the boiler today and saw it was set at 10 psi! Seems high based on what i have read here with most people saying my pressure should be 1.5 psi or less, there is also another box next to the Pressuretrol on the boiler that is set at 5 psi, not sure what the other Honeywell box is, as I am no HVAC expert. The pressure gauge was lying on zero every time i looked at it today, so i'm not sure if it's working or maybe i just didn't catch it at the right time. I replaced the clogged return run and now that is working great. I have 2 steam mains that are about 70 feet long each and 4" in diameter. What size vent's should be installed on that large of a run. And also should I replace the old vent on top of the old webster return trap with something more modern and better working? Thanks for any help

Henry

Steam efficiency

Besides the problems that you are experiencing, steam is the least efficient way to heat a building.  If you can get a bit of a budget, change over to hot water mod-con! Remember that the cast iron radiation was sized for INFLUENZA and grossly over sized! We have done numerous conversions to hot water with over 50% plus savings in energy consumptions. Our last one only had one riser leak! So for the naysayers, steam is for production and not for heating in the 21st century!

Prospect_Handy_Man

Boiler is Almost new

I would love to do that, but for now i just need to fix the current system since the owner is probably not going to change boilers very soon.

JStar

Steam

Completely disagree with this. Steam can be very efficient if installed and operated properly.

nicholas bonham-carter

Old systems

Lower the pressure to 1 ounce per floor for economy.

It's important to remember that old steam systems which have been neglected are burning more fuel for less results. Paradoxically, when the deferred maintenance of these systems are addressed, the fuel use is decreased, and at the same time the comfort level is increased.

As Henry says, there are some advantages to a hot-water system, but in your case, you will get a bigger bang for the buck by bringing the steam system you have up to it's originall state of operation. Just remember that the desire for economy is not a modern phenomenon.--NBC

Prospect_Handy_Man

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Prospect_Handy_Man

pressure settings

Just wanted to clarify what gauges I need to adjust. The gauge with cut in pressure should be set at 1 ounce per floor, so since it's three floors then 3 ounces? and what should the pressuretrol be set at?

Steamhead

Every "study" we've seen on the subject

has compared a steam system on the verge of total failure to a brand-new hot-water system. This is not, never has been and never will be a valid comparison. The only thing it's good for is pushing people to do work that is not needed to reduce their fuel consumption.



Another unanswered question is how long these mod-cons will last, since building owners who would neglect a steam system will certainly do the same with their mod-cons. This magnifies the problem since a mod-con needs more maintenance than the usual atmospheric or power-burner gas boiler. I seem to remember ME skipped maintenance on his mod-con to see what would happen, and the efficiency dropped alarmingly- and BTW, how would that affect the usual PVC venting?



Henry, if you want to keep saying this, YOU need to come up with the numbers. We want to see a comparison of a steam system in peak condition up against hot-water in peak condition. So far, we have not been able to locate any such comparison. YOU are taking the position, so YOU support it- if you can.



P.H., that Webster system was the Cadillac of heating in its day, and is still one of the best out there. It obviously needs some maintenance, but not a complete replacement.



What is at the ends of the steam mains now- crossover thermostatic traps? Float-and-thermostatic traps? Ordinary main vents? Nothing? Take some pictures and post them here so we can have a look.



And the pressure settings have nothing to do with the height of the building. Steam doesn't care if it's going up or down. All it's looking for is wherever the pressure is lowest.

Dave in QCA

Broad Sweeping Statements

Are Never accurate!   Oooops!   I mean usually not accurate!



Henry,

I would never go so far to say that steam is the most efficient way to heat a building, but who knows, in certain circumstances it might be close.  But to say that it absolutely the least efficient, is of course, not true.



It might be more accurate to say that systems that are poorly maintained, poorly controlled, with poor combustion efficiency are the least efficient way to heat a building.  I can think of examples of forced air, gravity hot air, hydronic, and steam that would all fit into this category.



As a former operating engineer / facilities manager in a large healthcare facility and with many other projects in historic homes, I've had more than a little practical experience along the way.  But, I am not an engineer nor a contractor and do not claim to have the professional experience the a person in either of those fields might have.



When I bought a building a few years ago, the first residential steam/vapor system that I have encountered, my first inclination was to convert to hot water.  But, only 7 of my 30 radiators are hot water type with the rest being steam only configuration.   This forced me to study steam/vapor and to figure out how to make the system work the way it should.  In 2008, the building temperature was inconsistent.  Temperatures fluctuated widely, some spots were hot, some were always cold.   I took a gradual approach to system repairs and changes.  Now, as of this point in time, the space temps are steady with all spaces in the buidling being within a 2 degree spread.  This has been accomplished by repairing steam traps, installing inlet orifices, and a good temperature control.  When it came time to replace the boiler, that was done too.  System is now running at 83% efficiency, smooth, comfortable, consistent.   The only electric power that is consumed is about 90 watts, when the burner is firing.  No other motors, fans, pumps, etc.   Although I have increased the heated space in the building by over 1200 sq ft, the energy consumption has decreased by 33%.



Now, would the energy usage at this building be further reduced by switcing to a modcon boiler and hot water?  Of course!  But how much?  At most, about 10%.  But, when energy for pumps is factored in, it IS afterall a big building, the savings would be somewhat reduced.  If I had to install fan coils to replace the steam only radiators..... well... there goes a little more.  And of course, without the radiant effect, there goes some of the comfort too.



Most of us look consider any investment on its rate of return.  I don't think my building is unusual in that the return on investement to convert from a well tuned steam system to hot water and modcon would just not be there.



In the meantime, I will continue to enjoy the comfort and economy in the building that is being heated by what you describe, "the least efficient way".

Prospect_Handy_Man

Vent Sizing

There is a link to pictures of my system in an earlier post on this thread. There are no traps at the end of the main lines because the legs at the end of the mains drop down into a wet return. But it has no vents at the end of the main. I measured both main steam lines from the header to the ends today and i have all accurate pipe length and size. I need to know what size vents i will need on each main, and how many of them i will need on each main. The first main comes off the header and runs a 4-in pipe for 75 feet, the pipe then reduces to 3-in and runs for an additional 72 feet to the end. The second main comes off the header and runs 4-in pipe for 82 feet, the pipe then reduces to 3-in and runs for an additional 52 feet, it reduces again to 1 1/2-in and runs for 20 feet to the end. I hope you guys can help me out. I really love getting this system working great again. Thanks for everyone's help so far.

Steamhead

Unusual

not to find some sort of venting device on a Webster steam main. If F&T traps were not used, they usually piped a 1/2" radiator trap between the steam main and the dry return. You might have to really look up to find it.



If there really is no vent, you'll want to install some Gortons.

Henry

Boiler & system efficiency

First of boiler efficiency of a steam versus mod-con is one big advantage to mod-con. Take your combustion analysis efficiency and now deduct 10%  loss by the steam boiler radiating in the boiler room. Don't believe me, look it up! Physical facts on insulated piping: the higher the temperature the higher the BTU loss to abient air. One more for hot water! Even if a vacuum system works properly, it cannot provide low temperature heat at 120F for an apartment block here at 32F. Steam heating system will often overshoot in fall and spring, not so with a mod-con. I have a gas bill of the Notre Dame Cathedral that I will scan tomorrow night. You will see the actual savings. Our conversion of the luxury apartment building from this fall has more than halved the consumption of natural gas per unit. We had only one return riser leak! BTW, there is just so much less maintenance on a mod-con compared to a steam boiler! No yearly insurance inspections, no water softners, no chemicals, no staitonary engineers (depending on power), no blowdowns that throw energy into the sewer, plus, plus! A properly installed mod-con requires service every two years. It takes all of two hours compared to how many hours on a steam boiler?

So what is the actual steam sytem heating efficiency in a commercial aplication? Probaly not more than 70% if it is in perfect shape!



Don't forget, I do fix many a steam system from one pipe vacuum to industrial aplications. But,if the heating client is willing to invest (like the one that gave us the conversion and 9 other blocks plus the $7M tower job) he will recoup his investments rapidly. BTW, we just completed a one pipe gravity hot water system to a hybrid mod-con and cat 1 on a property of over 400,000 sq ft and 10 floors. Except for problems with the Canus boilers, everything is running somthely with increased comfort.

Henry

Boiler efficiency

Don't forget that steam boiler efficiencies shown from manufacturers are all at 0 PSI! Increase the pressure, reduce the efficiency!

Steamhead

This would not hold true in the States

"No yearly insurance inspections"? "no staitonary engineers"  (you mean "stationary" engineers, don't you?) ? Not in most large American cities. Regulations vary, but in many places every boiler over a certain size, whether steam or hot-water, must be inspected. Here, we even see boiler registration numbers in residential installations.



 If your particular AHJ doesn't require inspections or engineers on mod-cons, it's only because they are new enough that they haven't killed anyone in that jurisdiction yet. Remember, Codes are generally written in the blood of the people that were killed before Codes came along.



"no water softners, no chemicals" Again, this depends on local water conditions and what the manufacturer wants. In Baltimore, the water is good enough that a cast-iron steam boiler should not need any treatment, and a cast-iron hot-water one most certainly does not. But I seem to remember some mod-con manufacturers requiring treatment.



Regarding your Notre Dame and the other job, you fail to mention what condition the steam systems were in. I'm willing to bet they were in pretty bad condition, and certainly not running at peak efficiency. And the overshooting is simply a control or distribution problem. Our customers don't have these problems- why do yours?

Prospect_Handy_Man

How Many vent's and what size?

I know i need to install some vents. the original vents wen't bad and were removed without replacing them, due to the lack of understanding the system. I need to know how many Gortons need to be on each main and what size they should be.

Steamhead

The "cut-in"

is another Pressuretrol. Does the other Pressuretrol have a reset button on the top or the front?

Prospect_Handy_Man

How Many vent's and what size?

I know i need to install some vents. the original vents wen't bad and were removed without replacing them, due to the lack of understanding the system. I need to know how many Gortons need to be on each main and what size they should be. The first main comes off the header and runs a 4-in pipe for 75 feet, the pipe then reduces to 3-in and runs for an additional 72 feet to the end. The second main comes off the header and runs 4-in pipe for 82 feet, the pipe then reduces to 3-in and runs for an additional 52 feet, it reduces again to 1 1/2-in and runs for 20 feet to the end. After I get the venting situation taken care of, i will concentrate on the system pressure, and i'll get you some photo's of the controls.

Henry

Show me your consumption per dwelling!

We design our systems for -20F. An average mod-con 4 1/2 or 5 1/2 apartment will consume between 1200 (42,377 FT3) and 1400(49,400 Ft 3) cub meters per year of gas which includes 400M3 for hot water needs. Now give me your figures for a steam heated apartment block in much warmer climate! We do over 300 replacements a year with a gas bill usually provided beforehand to see if a mod-con is a worthwhile option. Some are not!



As one goes to multiple smaller boilers, the yearly inspection requirements are not required. Plus, as one now can now micro-manage the energy use by having 5 to 1 or 10 to 1 or with the new Lochinvar boilers with 10 to 1 ratios, allow us to have 30, 45, 60 or greater to 1 turn-down ratios!

All of our gas installations are declared to the AHJ and inspected by the gas supplier or AHJ and in several areas, the municipalities. As a voting member of our National Gas Code, I take offense at your comments regarding how we decide on code requirements. It is a balancing act between AHJ wanting new rules that they don't enforce, new situations with new equipment and trying to harmonize with NFPA 54 and the International standards. I try to bring a balance from knee-jerk reactions to some incident. Each one needs to be studied and in the 99% of cases, code was not followed! I sit on 7 gas codes, and the only one at his expense! I am the ONLY independent member! I was asked to join in 2005. I have a bit of knowledge about what is code, standards & certification of appliances as I have even done that!

Prospect_Handy_Man

Venting???

I can appreciate the debate going on here, but the fact is that i'm not going to replace my steam boiler for a water system. I would really just like it if someone could provide some insight on the number of vents i need on each one of my steam mains and what size and brand they should be. Thanks to anyone who can answer that question for me, there are currently no vents on the steam main. The pipe length and dimensions are in my previous post on this thread.

BobC

start with 10 ea Gorton #2's on each main

Your first main contains about 10 cu ft of air and the second main has 9.6 cu ft of air. Both will require a lot of venting capacity. You could start with 10ea gorton #2's at the end of each main but it might be better to use steam traps for this size a venting requirement. There is a thread in the last couple of weeks that talks about using crossover traps instead of vents.



http://72.3.142.104/forum-thread/144854/Crossover-trap



Read that over and see if it might apply to your situation. If you did decide to use the Gorton #2's you would have to set up multiple venting menorah's on each main, you might well need more than 10 per main - you would have to measure the venting back pressure to see if 10 are really enough.



Bob

Prospect_Handy_Man

Thanks

Thank you for the reply. Now that i know the cubic footage i can figure it out from there, I just wasn't sure how to convert it.

BobC

Pipe size

Glad to help.



I assume the pipe measurements are pipe sizes and NOT the actual OD of the pipe? If the sizes were OD then the venting requirements would be less.



Bob

Steamhead

Bob's figures are correct

if you're venting the mains at one ounce pressure. One Gorton #2 will vent 1.1 CFM at 1 ounce.



But it might be more manageable to use a venting pressure of 2 ounces. Here, a #2 will vent 1.75 CFM and you could get away with six Gorton #2 vents on each main.



For reference, at 3 ounces a Gorton #2 will vent 2.2 CFM, At this pressure you'd need 4.5 #2 vents on each main, which you'd round up to 5.



These figures assume the target is to vent the main from the boiler to the end in about a minute. We sometimes don't do quite that well, but as long as the main fills with steam before the radiator runouts do, the system will be much easier to balance- typically requiring just some radiator vent, trap or orifice tweaks.



Regarding pipe sizes- yes, these are expressed as ID. If you measure OD, subtract the thickness of the pipe on each side- typically 1/8" in the smaller sizes and 1/4" as you go bigger- to get ID.

BobC

Question

How much can you vent through a 3/4" pipe? My copy of the venting chart does not state what 3/4" pipes are good for because of the limitations of the measurement method.



I'm just interested on how many Gorton #2's you could vent through a common 3/4" setup.



Bob

Steamhead

Here is one example

that you may not be familiar with.



Q: Why does Code require a 60-pound gauge on a hot-water boiler which has a safety valve rated at 30 pounds? Or, a 30-pound gauge on a steam boiler with a 15-pound safety and a Vaporstat that maxes out at 1 pound?



A: By Code, any boiler or pressure vessel shall have a gauge that can read twice the unit's maximum allowable working pressure (which is the point at which the safety valve opens).



Q; Why is this?



A: In the late 19th and early 20th centuries, boilers used to explode a lot. And people died as a result. Miraculously, some people survived, and some swore up and down there was no pressure in the boiler when it exploded. The gauge read zero. What had happened was the boiler was so over-pressurized, the pointer moved all the way around the dial to the post where the zero was.



So upon learning of this problem, ASME changed their Code, which has the force of law in all or most of the USA, to require the gauge to read twice the maximum allowable working pressure.



Blood.



As for fuel consumption figures, unless you're working with the exact same building and no changes whatsoever were made to the building except to the heating system, they don't mean much. But look at our Find a Contractor ad- on that building we reduced their gas consumption by a third, and solved their steam distribution issues as well. No other changes were made to the building in that period.

Paul48

Orifice

What's the orifice size of a #2? I'd assume you could figure it out that way.

Prospect_Handy_Man

Vent placement

Can i just put the vents on a tree made off of a 1 1/4" pipe at the end of the steam main, or do i have to tap into the three inch pipe at the end of the main, and put in a single vent into each tapping hole? Thanks :-)

Steamhead

The tree

will work fine. We do it that way all the time. Only caveat is to make sure the piping is pitched back toward the main so water will not collect therein. 

BobC

Don't know

A quick web search didn't turn up anything, I don't think Gorton publishes that info and nobody's about to take a hack saw to an expensive air vent.



Bob

Prospect_Handy_Man

Great

Thanks for everything Steamhead and Bob C. I'll get this venting project going.

Steamhead

Post some pics

when you're done- and let us know how much better it runs!

Rod

Venting Website

For venting ideas you might want to take a look at this website. It belongs to Gerry Gill who is a very experienced Cleveland steam pro.

http://www.gwgillplumbingandheating.com/webapp/p/415/maximizing-your-venting.html

- Rod

Prospect_Handy_Man

Traps Sabotaged

So Before I got to venting the main steam lines today, I thought I should check all the radiator traps on this steam system to make sure they are all in working order first. Well I think I found one of the problems with the system. 23 OF THE 38 TOTAL RADIATORS HAD THE TRAP GUTS RIPPED OUT OF THEM! The system can't build any pressure and it's taking the path of least resistance to some radiators and not others. Hence the hot and cold spots. Does anyone know where I can get a good price on traps, or trap inserts to repair or replace the old Warren Webster steam radiator traps? ALL of my pressure is running into the return lines and out the vent on top of the old Warren Webster vent trap.

Prospect_Handy_Man

Traps Sabotaged

So Before I got to venting the main steam lines today, I thought I should check all the radiator traps on this steam system to make sure they are all in working order first. Well I think I found one of the problems with the system. 23 OF THE 38 TOTAL RADIATORS HAD THE TRAP GUTS RIPPED OUT OF THEM! The system can't build any pressure and it's taking the path of least resistance to some radiators and not others. Hence the hot and cold spots. Does anyone know where I can get a good price on traps, or trap inserts to repair or replace the old Warren Webster steam radiator traps? ALL of my pressure is running into the return lines and out the vent on top of the old Warren Webster vent trap.

Dave in QCA

tunstall

Our friends at Tunstall have cage units that can slip back inside the old trap bodies.  Makes repairs much easier than installing new traps.

http://www.tunstall-inc.com/