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Balancing 1-pipe steam system
Newburgh70
Member Posts: 52
Hello,
This is my 1st home with a steam system. 4 story brownstone, new boiler. Assuming my boiler is sized correctly and all near boiler piping correct, I have some balancing questions. I believe the mains weren't being vented enough so we added alot. Building dimensions are 20x40. I don't know the exact dimensions of the main piping but hope the building dimensions help a bit to ballpark. Front risers are 4 feet from the main so the front is warmer then the back of the house and we are trying to balance that. I have a bigmouth on that main now (5th picture) and two Gordon #2s on the rear mains (see pics). The pics were taken before the vents were changed out for larger. Also purchased a vaporstat that is set to .75 PSI and changed out the Gordon D for a Gordon #1 on the top of the rear riser. All in all, a lot more venting. Its helping no doubt, but here are my questions:
1. I am still building pressure (although I haven't gone down to watch the gauge yet to see where it ends up). The reason I know that is because the radiators start hissing which drives me nuts. I have read countless threads on this site explaining how venting the mains quickly is the key to balancing a 1 pipe steam system. Our bedroom is on the top floor and isn't very big so we have a Gordon #5 on that for the sole purpose of slowing it down because it gets way too hot in that room. The original radiator for that room is quite large and overkill if you ask me but its original. Based on Gordons charts, i guess your not supposed to put such small vents on top floor radiators? I've read mixed reviews on that including @nicholas bonham-carter mentioning on another thread to not pay much attention to that. If I added all this additional main venting, do you think its possible based on the pics that I still don't have enough? Please take a look at the placement of the vents as well.
2. Should the system ever hiss? It doesn't do so when it goes on or is warming up. I guess its only happening when the radiators are already full? Should the pressure be turned down even more?
3. @Jamie Hall mentioned choking the front of the house more to compensate for the proximity of the boiler to the front main. I would assume this would only be for the radiator vents and not the main?
4. The spitting is much better and as I mentioned, only when on for a bit towards the end of a cycle.
5. Last, i have one radiator on the 2nd floor that is the slowest to heat up by far. Our steam guy added 2 vents to this one so it has plenty of venting but still cold in some areas. I'm not sure if it could be back pitched or what. Its sloped the correct way but no idea about the piping under the 100+ year old floors.
Thank you in advance!
This is my 1st home with a steam system. 4 story brownstone, new boiler. Assuming my boiler is sized correctly and all near boiler piping correct, I have some balancing questions. I believe the mains weren't being vented enough so we added alot. Building dimensions are 20x40. I don't know the exact dimensions of the main piping but hope the building dimensions help a bit to ballpark. Front risers are 4 feet from the main so the front is warmer then the back of the house and we are trying to balance that. I have a bigmouth on that main now (5th picture) and two Gordon #2s on the rear mains (see pics). The pics were taken before the vents were changed out for larger. Also purchased a vaporstat that is set to .75 PSI and changed out the Gordon D for a Gordon #1 on the top of the rear riser. All in all, a lot more venting. Its helping no doubt, but here are my questions:
1. I am still building pressure (although I haven't gone down to watch the gauge yet to see where it ends up). The reason I know that is because the radiators start hissing which drives me nuts. I have read countless threads on this site explaining how venting the mains quickly is the key to balancing a 1 pipe steam system. Our bedroom is on the top floor and isn't very big so we have a Gordon #5 on that for the sole purpose of slowing it down because it gets way too hot in that room. The original radiator for that room is quite large and overkill if you ask me but its original. Based on Gordons charts, i guess your not supposed to put such small vents on top floor radiators? I've read mixed reviews on that including @nicholas bonham-carter mentioning on another thread to not pay much attention to that. If I added all this additional main venting, do you think its possible based on the pics that I still don't have enough? Please take a look at the placement of the vents as well.
2. Should the system ever hiss? It doesn't do so when it goes on or is warming up. I guess its only happening when the radiators are already full? Should the pressure be turned down even more?
3. @Jamie Hall mentioned choking the front of the house more to compensate for the proximity of the boiler to the front main. I would assume this would only be for the radiator vents and not the main?
4. The spitting is much better and as I mentioned, only when on for a bit towards the end of a cycle.
5. Last, i have one radiator on the 2nd floor that is the slowest to heat up by far. Our steam guy added 2 vents to this one so it has plenty of venting but still cold in some areas. I'm not sure if it could be back pitched or what. Its sloped the correct way but no idea about the piping under the 100+ year old floors.
Thank you in advance!
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Comments
that's a bold assumption. Can you back it up?
(these numbers don't correspond to yours)
1. I don't see your pictures.
2. You have to see what the pressure is getting to.
3. A Gorton D is the exact same size as a Gorton #1.
4. If you're building pressure, you are almost certainly, by definition, oversized.
5. A system shouldn't hiss. You might hear air quietly escaping a radiator vent during cycle start, but you describe hissing with radiators full, and that shouldn't happen. It points to high pressure
6. Why are your radiators getting completely full? Are you operating with a temperature setback? You probably shouldn't...it amplifies the problems from an oversized boiler
If a radiator gets too hot too fast, there's no problem putting smaller vents on it. It may exacerbate an oversized boiler but the alternative is you are just wasting fuel.
Sorry, forgot to attach them. @ethicalpaul, you reviewed pics of my boiler and near boiler piping a week or so ago and complimented on how nice it was done. Its 156k BTUs. Building is roughly 4000SF.
I am operating a setback at night to be comfortable to sleep but nothing crazy. I have it set for 66 degrees at night from 11pm-5:30am. 5:30am it kicks on to 68 and I can hear the radiators start hissing in my bedroom which is on the top floor. 6:30 Is another adjustment on my Ecobee to get to 70 degrees.
Do you think its possible I still don't have enough main venting? Would that inadequacy cause this? ill check pressure when i get a chance. Its warm today.
When the boiler starts to make steam (you can tell because the header gets too hot to hold onto), then start running round to your main vents to see if they are working. Then see how long it takes steam to get to them, then see if they shut correctly against the steam.
You can run around touching the pipes (that's what I do), or you can use an IR camera or an IR/laser thermometer device.
If you do this a few times you'll really see what is going on with your system. And keep an eye on your boiler pressure during these exercises and you'll learn what's going on with your pressure.
It should be:
1. low pressure during mains filling with steam (the main vents are open)
2. A period of time of slightly more pressure (but only a few ounces max) when the radiators are filling up (this period could be an hour or more)
3. A period of rising pressure as radiator vents start closing
Get up early and watch your system recover from its setback and you'll learn so much
18 Ounce per Square Inch Gauge
Time Delay Relay in Series with Thermostat
Operating Pressure 0.3-0.5 Ounce per Square Inch
Assuming the near boiler piping is 100% correct and the boiler is sized correctly, do you think its possible I still don't have enough main venting? Two Gordon #2s on the rear and one bigmouth you would think would be enough. Also, what do you suggest for the front of the house always getting warmer then the back? Keeping the big mouth on the front main and chocking all the radiators in the front all the way up, on each floor? What about that one radiator that is super slow to heat and is cold in some spots?
What is a reasonable amount of time for all radiators to be hot in a nicely balanced system? I know for sure all of my radiators dont get hot at the same time, that Im certain of BUT I have ran across the house to touch the front riser and the back riser and they both seem to be hot to touch at the same time.
@acwagner - I have been playing around with this a bit. Problem is, I have tenants who are on the ground floor who are the 1st ones to get the heat as they are closest to the boiler. I dont want to be sweating them out at 5am. I already have it on at 5:30. I see your point though and realize the setback has the potential to cause pressure. Thing I don't understand is why the vaporstat wouldn't turn the boiler off if that was happening. I guess thats why my boiler guy said to turn the vaporstat down a notch?
I really want to balance this system as best as possible. Getting there for sure.
I found that my vents will noticeably hiss at like 6-8 ounces/inch of pressure, so my experience is you don't need "high" pressure to get undesirable noises. I don't think vaporstats are calibrated that well, so it's possible your vaporstat is not being triggered exactly at the settings you have.
Temperature setbacks get mixed reviews on this site, mostly because big changes in temperature like that generally highlight all the flaws in the system. I personally do one at night for comfort reasons, but it's only 2 degrees.
18 Ounce per Square Inch Gauge
Time Delay Relay in Series with Thermostat
Operating Pressure 0.3-0.5 Ounce per Square Inch
Also, it looks like you have an old main vent here that needs to get upgraded:
Is that on the slower main side?
18 Ounce per Square Inch Gauge
Time Delay Relay in Series with Thermostat
Operating Pressure 0.3-0.5 Ounce per Square Inch
looks like this was the one that was installed:
https://www.statesupply.com/hn1113g
Picture #5 appears to show a sagged elbow in the area above box “54”, so time to put a level on it and verify that all the pipe pitch is correct.—NBC
but small adjustments though
@ethicalpaul I wouldnt say any main is slower then the other as both 2nd floor risers are getting hot at the same time. My problem is hissing.
The only way to check the main venting is when the boiler comes out of setback and the steam pipe coming out of the boiler starts to get hot see how long it takes to get steam to the end of the main(s)
Sounds like the pressure control you have is not a vaporstat if it's calibrated in PSI
How many radiators do you have, and how are the radiators piped to the main? You mentioned that you have a few risers with vents--are all the upper floor radiators off a common riser?
I'm just trying to understand how this system is piped. That makes a difference, in my opinion. If, for example, every radiator had it's own take off from the main, you'll vent those differently than if some share common risers. Also, since your home is 4 stories, it sounds like the horizontal mains in the basement are a small portion of the overall piping. The 4th floor radiators probably have like 35 ft or more of vertical pipe to get up from the basement.
18 Ounce per Square Inch Gauge
Time Delay Relay in Series with Thermostat
Operating Pressure 0.3-0.5 Ounce per Square Inch
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
@acwagner this isnt my house but its a similar floor plan so you have a good idea on the layout. This also appears to be a 2-pipe system and mine is a one but you get the point. https://streeteasy.com/sale/1396116
There is a radiator in every room including the foyer.
Pic 1- This is of the back of the basement and the small window you see there is facing the backyard.
Pic 2 & 3- is of the left rear of the house.
Pic 4 is of the right rear of the house which also extends further inside of an uninsulated wall. I wouldn't be surprised now that I look at it if that's the slow heating radiator.
35 feet of riser piping is certainly in the ballpark.
I think what my contractor is attempting to do is vent the rear more because that's the colder side of the house. Picture #5 is very close to the boiler which now has a Gordon #1 on it. The question of the day is if that front main (pic #5) was inadequately vented, would it be causing these issues? I think he is trying to slow down the front so we added a ton of venting to the rear. The front also hisses much more then the rear.
@Jamie Hall I can make the top of the rear riser even bigger if needed.
There is no way we are going to be able to sleep without a setback so that's not an option. The total setback from overnight is 4-5 degrees. Im already doing increments on the Ecobee so its not all in one shot and its increasing gradually but the hissing wakes us up every morning and drives us mad. Also, I have the Ecobee sensors all over the house. There is no doubt the front is getting hotter then the rear of the house while the boiler is on and its substantial. So... how do we solve the pressure issue and the font/back imbalance?
Why? Because it is entirely possible that part of the problem may be that the installed radiation is none too well matched with the current way the spaces are being used. Just because it's always been there doesn't mean that it's correct for today's uses!
Then we can go back to venting. Where your building has such long risers, we need to think of them as mains, as I said -- and so what we are looking for is to have the steam arrive at the tops of the risers at more or less the same time. We are also looking for the venting to be adequate.
I'm not a real big fan of calculating vent size based on riser size. Rather, I'd like to see you have a low pressure gauge on the boiler and then pay attention to what it does when the boiler fires. If, once steam starts to be made, it rises quickly to a few ounces -- with one pipe steam, perhaps as much as 6 ounces -- and then holds fairly steady until all the radiators start to heat, you have enough main venting. If it keeps rising, you don't. It will start to rise again as the radiators start to fill.
Now let's think about what happens with badly unbalanced lengths of mains. Problem. If there is adequate venting on the main, the steam will move in the main at a certain velocity -- and ten to 15 feet per minute, even with a well-insulated main, is about all you can expect if the main is cool. More venting isn't going to change that. No insulation will, however -- that will slow it right down. What will happen with unbalanced main lengths, however, is that the shorter main is going to get steam to the end faster than the longer one. Now here's where you're going to need a very sharp eye on that gauge (and even then it may be hopeless): when the short main finally fills, if the longer main -- or mains -- hasn't, there should be a small -- very small probably -- rise in pressure. So long as it is very small -- so small that you think you are imagining it -- that's fine. If not, then that longer main (or riser) could use a little more venting.
Now we've got the main/riser venting. Next -- that long riser is still slow. Can we speed it up? The related question is -- is it insulated? If not, can you insulate it? If so, do.
And that's about all that can be done to even out steam delivery to the various radiators. At this point, it becomes a job of getting the heat delivery from the radiator to the space the way you want it, and has been said once or twice, start out by slowing the venting on the radiators which are too enthusiastic (in two pipe it's much easier -- just partly close the valve. Can't do that on one pipe!). If the radiator is significantly oversized in relation to the heat load, you can also reduce its output -- perhaps build a nice enclosure around it. Put a blanket on it. As an extreme, if there is also a room where the radiator is too small, swap radiators (if it doesn't wreck your home decorating job!).
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
The radiator in our bedroom is too big, no doubt, especially after spray foaming the cockloft. Other then that, i would say all other radiators in the house are sized correctly for the room they serve.
I get what your saying about the risers. I can add a Gordon #2 on the end of the rear riser. There is no front riser to put a vent on. I would imagine it branches off under the floor to the two radiators it serves that face the front of the house. I already have a Gordon #5 on this radiator and its still pretty hot but barrable but it does hiss a lot. Again, I am building pressure for sure as the system stays on, especially at morning startup from the setback.
Getting back to the main venting-
If you look at the pics, the front has a Gordon #1 now (pic 5) and the rear has an enormous amount of venting now. two Gordon #2s and one bigmouth. I wouldn't think there is anyway possible the rear needs more venting. My concern is the front vent which currently has the Gordon #1 on it. I feel my contractor doesn't want to put a bigger vent on this one because the front is already too hot as it is and he is trying to push the steam more towards the back of the house. I understand the logic, but not 100% sure I agree with it after all I've read and comments here.
What you are saying is vent the front main even more to be a Gordon #2 or even a bigmouth and then worry about controlling the output of the radiators themselves, correct? My contractor is saying we are getting too much steam in the front and to maximize the venting in the rear to direct the steam that direction. Again, I understand his logic but all I know is we still have way too much pressure and hissing.
If im understanding the vote of the forum is to vent the rear riser even more, to maybe a Gordon #2 and vent the front main even more to be the same and/or a bigmouth and take it from there to see if this fixes my pressure building issue?
But I really do think you need to check the steam arrival time -- since there really isn't a riser on the front, compare when it gets to the first of those radiators with when it gets to the top of the rear riser.
Something else going on here with the pressure rise, if it's over a few ounces and continuous... haven't put my finger on it yet.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Then let us know the times. That will give a feel for how far off things are.
18 Ounce per Square Inch Gauge
Time Delay Relay in Series with Thermostat
Operating Pressure 0.3-0.5 Ounce per Square Inch
If his main vents in the basement are doing their job there is a lot of air in the risers that the radiator vents can't handle as @Jamie Hall mentioned
NJ Master HVAC Lic.
Mahwah, NJ
Specializing in steam and hydronic heating
what are you seeing on the gage?
and I will ask if the pigtail has been checked for clean and clear back to the boiler?
post a general picture of the Ptrol or Vstat, and sightglass
18 Ounce per Square Inch Gauge
Time Delay Relay in Series with Thermostat
Operating Pressure 0.3-0.5 Ounce per Square Inch
Lets make a couple of assumptions just for this theory. Lets assume my boiler is correctly sized and all the near piping is correct. My mains are not insulated @clammy but its on my list of things to do but lets assume they were. Im supposed to vent the mains as quick as possible, and I understand why. What I don't understand is how the risers vent. We said that the front of the house is hotter and heating up quicker due to the location of the boiler. I added more venting to the rear risers to try to get heat everywhere at the same time. The rear riser goes all the way to the top small bedroom and that bedroom does not have a radiator nor does it need one. The riser itself is putting out enough heat. There is a Gordon #1 at the top of that riser. I understand all of this logic.
Now, the front main only has a Gordon #1 and there is no "top of the riser" for the front of the house. That riser breaks off in the top floor and goes to two radiators. When the system is hissing, pretty much all the hissing is only happening from the front of the house. So... How does the front riser get more venting? Would this be changing out the Gordon #1 for much more venting and it would get all of the air out of that 30+ foot long riser? I would imagine this would be the only way to solve this problem because my radiators are doing the main venting also and this is causing the hissing?
Assuming this is the case, and my theory is correct, then the only way to slow down the front from heating up much quicker then the rear is to put smaller vents on the radiators themselves but not look to have less venting such as we do now, on the main?
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
NJ Master HVAC Lic.
Mahwah, NJ
Specializing in steam and hydronic heating