Balancing the Steam System in my Building

FJL

I have a one pipe steam system in my four story apt building.  I have a 2.5 inch basement  main that is 50.5 feet long and vented with one Hoffman 75 and three Gorton No. 1 vents.  Those vents are a shade under the total cubic feet of air in that pipe (1.515 cubic feet vs. 1.499 venting capacity at one ounce).



The radiators in the top three apartments are fed by five risers, two of which are fed directly from the header of the boiler and three are fed from the main.  Each riser has 2 Gorton No. 1 vents at the top of the riser in the third floor apt.



This morning, I timed the arrival of the steam in each steam riser in my apt from a warm start.  I think this was the second or third run after the boiler ran to recover from the night time setback.  The two risers fed by the header feed the living room and steam hit those risers within 35 seconds of each other.  2:10 minutes later, the steam hit the first riser fed by the main.  23 seconds later the steam hit the second riser fed by the main, which is 24 feet down on the main.  29 seconds later the steam hit the riser at the end of the main.  So on a warm start, the steam took 3.5 minutes to hit all of the risers in my apt after hitting the first riser.



I have a low pressure gauge attached to the radiator fed by the riser located 24 feet down the main.  This riser feeds a radiator in the master bathroom.  The needle on the gauge was still hovering at zero 18 minutes steam had hit the riser feeding that radiator.  Two minutes later, the gauge registered about one-half ounce and one minute after that it registered one ounce, at which point the t-stat was satisfied and the boiler turned off.



My concern is the amount of time it seems for pressure to build to the point where the rads will heat up.  The bathroom rad is slowly getting hot while the need hovers at zero ounces.  Not until is starts to rise to 1 ounce does it get fully hot.  The rad in the bedroom had been receiving steam for 21 minutes, but portions of it were not hot  This is a thin tube rad with 14 sections that have six tubes per section.  Sections 4-12 were warm at best, except for the very top of those sections. 



The problem is that on days not that cold, the t-stat, which is controlled by a sensor in the living room in the front of the apt, is satisfied before pressure builds in the rear of the apt to the point where the rads fill quickly with steam.  I am trying to determine how to better balance the system. 

Jamie Hall

Keep in mind

that it is not pressure which makes the radiator warm.  What you are seeing is not unexpected -- steam is coming into the radiator, but is condensing just as fast as it gets there.  The pressure will not begin to rise significantly at the radiator until the rate of steam coming in is greater than the rate at which it condenses (the pressure at the boiler is another story; the two are not the same, due to losses in the piping).



Have you done any fiddling with the vents on the various radiators?  I would say from your post that you have done a good job of venting the risers and all -- they variation in timing between them is remarkably small.  You might, if you haven't already, try varying the venting rate on the slower radiators, to see what that does.

FJL

Radiator Vent Sizes

You make a good point about the pressure inside the rad being a function of condensation.  I hadn't taken that into consideration.



I've fiddled a bit with radiator vent sizes.  My boiler contractor added extra vents to the main and the risers when the new boiler was installed two years ago.  But for some reason, the same contractor sized the radiator vents based on the floor rather than their closeness to the boiler.  All of my rad vents were Gorton No. 6.  The third floor got Gorton Cs, and the top floor got Gorton Ds. 



This year, I put a Gorton D on my bedroom radiator, and it has helped as compared to past years.  A few days ago, I changed the vents on the rads in the living room on the top floor apt where the t-stat sensor is located.  We removed the Gorton Ds from those two rads and replaced them with Gorton 6s.  I was thinking that I could delay the amount of time it takes to satisfy the t-stat by slowing down the rate at which those rads fill with steam and heat up.  I was hoping this would allow the boiler to run longer and give the rear rads more time to heat up.  Another idea is to double vent the rads in the rear -- attach a tee to a 1/8 nipple and attach two vents to the tee. 

Jeremy_16

Riser Vents

I asked a question on this board earlier about tapping a hole for riser vents on the third floor of a four story building. I too have a 4 story building and was thinking about adding a vent at the top of the risers on the third floor. Has that helped a lot? Do you have any pictures?



Since you have main vents and riser vents, you can probably vent the radiators based on their size and not geographical location. The contractor probably put the the larger vents on the higher floors because he thought it would take longer for the steam to reach them, but if you have riser vents and main vents and the steam seems to reach all places at about the same time as you indicated, then try adding bigger vents to bigger radiators and smaller vents to smaller radiators instead of just adding the Gorton Ds to all radiators just because they are on the top floor.



We double vented a few large radiators that were slow to heat and I think it helped. We put a Gorton D at the top of the radiator and a slower adjustable vent in the middle. If anything, try to speed up the steam when balancing, rather than slow it down. That way you'll save money on fuel rather then letting the burner run longer.

FJL

Riser Vents

I think that the riser vents have helped, but it is hard to tell because, until recently, the heat system in my building was a mess.  We had an old boiler piped with a bull head; the main in the basement was insulated; the t-stat used to be located in a common hallway and would turn on and off based more on when people entered and exited the building rather than temp inside anyone's apt.  All of that has changed. 



I don't have any pictures of the riser vents.  They are in my neighbor's apt.  Maybe I can get a chance to take a picture, but she's not around that much.



One reason it occurred to me to vent based on proximity to the boiler is because living room rads, which are fed by risers connected to the header, have no problem getting hot.  I believe that is partly because they get steam steam quicker because they are connected to the header.  It seems to me that those risers and rads are aided in their ability to get steam and get hot by how they are connected to the header.  I figured that slowing down the venting of those rads would allow the rads in the rear to heat up.  Sure, the boiler runs longer if I slow them down, but if I don't, the rear of the building is not getting sufficient heat.  So I will necessarily burn more fuel but I don't know that I'm wasting fuel because I need to burn that fuel to heat the space.  I hope that makes sense.

FJL

Riser Vent Photos

OK.  My neighbor was home and I just popped upstairs to snap a picture of a few of the riser vents.  Here goes:

Steamhead

Increase your main venting

Start with two Gorton #2 vents. You want to minimize the difference between the header-fed risers and those fed from the main. 

FJL

Gorton #2

I am a bit confused.  Are you saying I should add two Gorton #2s to the venting I already have on the main (a Hoffman 75 and three Gorton #1s) or that I should replace two of the Gorton #1s in the main with Gorton #2s?  I'm willing to try that, but don't I already have enough venting for the main?  I thought that over venting, if that is what adding two Gorton #2s would do, can't increase the time it takes to vent the main once the venting matched the cubic square feet of air that can be held by a particular size and length of pipe.

Jeremy_16

Thanks

Thanks for posting those pictures. That's pretty interesting to see. In our building we moved the top floor radiator over and put a "master vent" where the supply valve was located. I had been wondering going forward if I should use the same method (if needed on other risers) or just add them to the top of the third floor. That way I don't need to move the radiators.



Some of those venting stations in the pictures you sent seemed to have a lot of pitch? Do you know if the vents work correctly at that much pitch? Also, have you checked to see if you have enough venting on the risers that are far from the boiler? Do you have riser vents on any of the risers fed directly from the boiler?



I'm still wondering how much of a benefit it is to have maximum venting at one ounce of pressure because at two ounces it seems like vents can vent almost twice as much air. I wonder how long it takes for most systems to go from one ounce to two ounces at the vents...If it's only a short time, then does adding extra vents really help that much? I haven't done enough tinkering around to know the answer. Can someone explain this?

FJL

The Vents

When I had a new boiler installed two years ago, my contractor considered installing a "master" vent on the supply line, but he decided against that because he did not want to get involved with moving radiators. 



Those vents are on all of the risers, including those fed by the header.  I don't know how much they help.  The upstairs residents had complained of not getting enough heat and of the radiators not getting hot.  The riser vents were added in response to that specific complaint.  FWIW, one of the other bidders explicitly rejected that idea, saying that it wouldn't help much. 



I hadn't thought about how the performance of the vents would correspond to their pitch.  I had assumed that the person who installed them knew what he was doing, but maybe less pitch would make them perform better.  I don't know. 



I still do get hissing on many of my air vents, for radiators close to and far from the boiler.  I notice the hissing usually starts, on the rads far from the boiler, when the pressure inside the radiator hits one ounce.  Before then, mostly quiet.  One air vent hisses constantly, while another hisses occasionally.  I've been told that hissing vents is a sign of insufficient venting. 

FJL

Better Balance

Starting last Sunday (2/7) I installed Gorton No. 6s on the living room radiators in the top apartment where the t-stat sensor is located.  I also put a Gorton C on the radiator in my master bathroom, and I put Gorton Ds on the radiators in the master bedroom and master bath in the third floor apartment (above mine). 



Since then, I have been getting more heat in the rear of my apt, where the master bedroom and bath are located.  It has not been super cold this past week.  Temp has been in the 30s range, but that was the temp range that was giving us most of the problem with insufficient heat in the rear.  Slowing down the venting on the top floor has resulted in a longer run time and more steam for the back of the building.



I am still getting a constant hiss from the large radiator in my bedroom when the steam runs for a long time, usually the first two or three runs from the evening setback.  I'd like to find a solution to that problem.  But so far, the change in vents on the radiators in the front and the rear of the building has improved the heat situation.

FJL

Double Venting the Radiator

I went ahead an double vented the large radiator in my bedroom using a nipple and a tee.  I did that because there were times when the boiler would cycle off due to pressure but the entire radiator was not hot and the air vent would hiss.  I thought maybe the rad wasn't being vented sufficiently. 



Anyway, I had a long boiler run this evening, and my bedroom radiator was hissing.  Upon closer inspection, I noticed that one of the two vents was hissing.  The other was silent.  One vent was a Gorton D and it was the silent one.  It was hot though.  The other vent was a Gorton C and it was the hisser. 



I'm a bit puzzled why only one of the two vents would hiss.  I'm just trying to understand what is happening with this radiator.



Thanks.

Jeremy_16

Double Venting

So both vents are coming off on either side of the tee and about half way down on the radiator? That is kind of strange that the D was silent and the C hissed because they are essentially in the same location. The D is bigger and may have snapped shut before the C did, but you would think that if steam reached the D vent, it would have also reached the C.



I know people that have used your method and they seemed to think it worked well. However, the best method would be to drill and tap a vent location above your first location and place the large vent (the Gorton D or a tee with the D and C) at the top and a slower vent at the bottom (see Lost art of Steam Heating page 113) Dan talks about John Schulz's "six most important things to improve one pipe steam systems performance" Double venting with one vent above another is one of them. The large vent at the top gets steam into the radiator quickly and then snaps shut.  Once steam is in the radiator, the lower vent, a slower vent, will allow steam to continue to slowly fill the radiator, even after the top vent has already shut. Rather than throttling back the heat, you should try to balance with this method.



We did this in three apartments with wall hung radiators on the first floor of a building. I'm still trying to improve the heat in those apartments, but the double venting definitely improved the situation. The tenants reported an improvement. We have a heat-timer in that building and we were able to adjust the settings so that the boiler ran for a shorter overall amount of time each day. We used to need to really overheat the other floors to get decent heat to the first floor.

jpf321

it could simply be that ..

the C has a bit of crud or something that is keeping it from sealing .. you can try boiling it in white vinegar as has been mentioned here .. or you can try a few squirts of WD-40.. you want to make sure that any and all crud is out .. maybe even some compressed air if you have it available .. what about if you tap it a bit when it is hissing? does it quiet?

FJL

Vents

Jeremy:  I understand your point about not throttling the other radiators in the building, but I slowed the venting on the rads in the room with the sensor to solve a different problem.  I had noticed that sometimes the t-stat would be satisfied before steam had the oppty to travel to the rear of the building.  I slowed the venting of the rads in the front of the building to give sufficient time for the steam to travel through the main and the risers that feed the rads at the rear of the building, not to give more time for the rads to vent after steam had hit them.  



JPF:  I will check out the vent to make sure it is clogged, but I don't think that is the problem.  The Gorton D is brand new and had been hissing in the same manner as the Gorton C, which is not brand new. 



I have tried tapping the hissing vent, but that doesn't work.  I can get the vent in the bathroom to stop hissing if I tap it.  What does that tell me about why it hisses? 



One more thing:  I am noticing that the Gorton C that hisses is making a "wet" hissing sound.  It sounds like moisture is trapped in there.  A tiny bit of moisture will sometimes collect just outside the hole, but water does not spit and leak onto the floor.   

jpf321

how's your pitch?

how's your pitch? how wet is your steam? is your vent T level? perhaps it should have been in-line ... rad nipple, T, vent (on top of T), nipple, elbow, vent (on top of elbow). extended outward .. should be able to use same parts but reconfigure the arrangement.

FJL

Steam

I don't really know how wet my steam is.  I sounds like it is wetter than it should be.  Pitch seems fine and the air vents are level to each other. 



All I know is that, based on the low pressure guage on the bathroom rad, the vent doesn't hiss in that rad until the pressure hits one ounce.  I assume that the same is true for the nearby bedroom rad.



And what does it mean that I can sometimes stop the hissing by tapping the vent?



I understand your suggestion rearrange the double vent layout, but I don't have enough space to do that.  The rad sits in a small alcove of sorts and the vents are already nearly up against the wall. 

TheSuper470

Balancing the Steam System in my Building

I think one of the things you should consider is what type of radiators you have. Mixing radiators such as cast and fin type could give you trouble when trying to balance the system.

You could also put heat timer vari valves on the riser, they are adjustable. How many pounds of steam are you pushing? What type of control panel do you have? Your sensor for the XYZ setting is adjusted by putting the sensor on the radiator last on the line. If it is there, maybe check it to see if it is operating correctly.

jpf321

perhaps...

since that vent seems to be ok somewhere else (did I read that correctly?) .. perhaps you can de-union the rad at the inlet and see if you can tip it to drain out any water that may be sitting in its bottom .. perhaps there is a puddle of water in bottom of rad which is causing wetter steam in that rad only ..



i used to have to tap some vents .. but now i don't .. i can't think of what i did to change anything except eliminate my setback (69dF all the time now) and perhaps lower my pressure (5oz cut-out and I never cycle on pressure, so it's actually moot)

FJL

Vents

I admit my post was a bit confusing.  I was talking about two different hissing rads, one in the bedroom and one in the bathroom.  The valves I was referring to have not been switched from one to the other, but I have, in the past, changed vents, and have even installed brand new ones, and the hissing problem, to the extent that it exists on an particular rad, is constant, notwithstanding changing of vents.  Water being trapped in the rad is very possible, espeically since I can hear what sounds like boiling water in a rad in the front living room, but that rads heats with no problem and an occasional hissing.  I suppose I should recheck the pitch to make sure the pitch is sufficient.



One more note about hissing.  The rad in the bathroom hissed more when the cut out was 16 ozs.  I lowered it to 12 ozs and the hissing is greatly reduced.  Maybe reducing it further to 8 ozs would help even more.  The reduction in cut out has not had the same effect on the larger rad in the bedroom.



All of my rads are the same kind -- iron.  I don't have any fin rads. 

FJL

Radiator Level and Pitch

The pitch of the hissing rads is fine, but I notice that the rads are not level on the ground from side to side.  They are listing to some degree.  Could that result in trapped water?  If so, I'll need to put splints or something to make the rad level from side to side in addition to making it pitch toward the inlet valve.