Building not being heated evenly

archer874

Hello everybody. I'm new to the forums and I have a 12 unit building in Queens that has too much heat in the front of the building and not enough in the left rear of the building, which is about 105 feet from the boiler. I had about a half dozen local pro's come and take a look and no one was able to tell me where the problem is, so I checked all the main vents and made sure they are working. The steam just seems to lose pressure when it reaches the back of the main.
I purchased Dan's book the lost art of steam heating and started reading .I found a few problems with the boiler piping and got excited so we went to work and made it correct, unfortunately that didn't fix my problem . I checked the A dimension height and found it to be at 42'' ...I checked the boiler it self and made sure all the ribs in the boiler were clean and not clogged and the flame is blue on the bottom and yellow and red on top...it seems ok. I also made sure the radiator valves are not clogged ...and at this point I am at a loss and would appreciate any suggestion on where to look and what to check next.

KC_Jones

You say the main vents are working, but how many do you have? You need to measure the length and size of the mains to determine how much main venting you will require. With a system the size it sounds like, you will need a lot of main vents. Is this 1 pipe or 2 pipe system? Are you looking for a pro to come out and look at it? If so let us know where you are and we may be able to recommend someone.

vaporvac

He's in Queens. So, do you know the total edr of the rads in the building and the sq ft of steam rating for the boiler. Any pics of the boiler piping and a representative radiator?

Abracadabra

Make sure you have slow vents on the radiators. Slow as in something like MOM #4 or Hoffman 40s. Make sure your mains are vented very fast. Not just having working main vents.

archer874

Thanks for the response . The boiler is a Burnum 702,000 BTU Single pipe system. Because of the Original boiler piping I thought that the boiler was producing wet steam so I re piped the header to get the steam and the condensate to flow in the same direction.
3'' riser out of the boiler into a 4'' header into two 3'' take off's .
The take of for the front of the building splits to the left and right side of the building approximetly 50' on each side with an EDR of 800 . I installed Maid O Mist #4 air vents on all the radiators in the front of the building on all three floors , I also removed the air vents from the front mains trying to move the steam more quickly to the back.the front of the building is still at 80 degrees while the back left is at 68 .There is an EDR of 800 in the rear of the building .The rear take off is 3'' and runs for about 52' where i have a Groton #1 3/4 quick vent. 6 feet before the end it turns left into a 2 1/2 pipe which runs 24' where I have a Groton #2... this is where the lack of heat starts...the main turns again and is 28' long where I have two Groton #2 air vents before it goes in the return.. There is almost no steam pressure at the end of that run and the last two main vents never get hot enough to close, they are hot but not hot enough..the boiler never turns off on pressure .

archer874

Before and after pic's

archer874

By the way the cut in is set to 1/2 and the Diff wheel set to 1 . The boiler never turns off on pressure .

archer874

The thermostat is on the third floor on the left rear side of the building, in the coldest apt

KC_Jones

By my rough calculations you are light on main venting for the rear main. There is a (controversial) rule of thumb around here of 1 Gorton #2 for every 20' of 2" pipe. By those numbers you would need around 10 Gorton#2 vents on that rear main. Since you mention you know the steam isn't going the entire length of the main this could support not enough main venting. Hopefully a pro with more experience on these large systems could comment if that is out of line, but from what I have seen I don't think it is. I am curious what size rad vents do you have on the rads for the rear main? If you have too big of vents on those rads some of the first rads could be sucking up the steam before it gets far enough down the main. You want the entire main vented before the rads start getting steam. Then vent the rads slowly.

nicholas bonham-carter

You definitely need more Gorton 2's on those mains. I have 45% more boiler capacity than you, and 18 Gorton 2's and 6 Hoffman 75's on 6 dry returns. A low pressure gauge will show you when the resistance (backpressure) of the escaping air is low enough (2 ounces) to be beneficial.
In your pictures, do I see the takeoffs from the header between the 2 risers coming up from the boiler? If so, there is a possibility of wet steam being the culprit here. The steam should enter the header at one end, then leave in the middle, followed by the equalizer to catch the water.--NBC

nicholas bonham-carter

Maybe a clearer photo of the piping will help us determine if there is a problem. The left photo shows very funky piping, and the right shows, I believe, the takeoffs between the risers, or so it seems. One of those mains would therefore get much wetter steam than the other.--NBC

JStar

KC_Jones said:

By my rough calculations you are light on main venting for the rear main. There is a (controversial) rule of thumb around here of 1 Gorton #2 for every 20' of 2" pipe. By those numbers you would need around 10 Gorton#2 vents on that rear main. Since you mention you know the steam isn't going the entire length of the main this could support not enough main venting. Hopefully a pro with more experience on these large systems could comment if that is out of line, but from what I have seen I don't think it is. I am curious what size rad vents do you have on the rads for the rear main? If you have too big of vents on those rads some of the first rads could be sucking up the steam before it gets far enough down the main. You want the entire main vented before the rads start getting steam. Then vent the rads slowly.

Controversial?

KC_Jones

JStar said:

KC_Jones said:

By my rough calculations you are light on main venting for the rear main. There is a (controversial) rule of thumb around here of 1 Gorton #2 for every 20' of 2" pipe. By those numbers you would need around 10 Gorton#2 vents on that rear main. Since you mention you know the steam isn't going the entire length of the main this could support not enough main venting. Hopefully a pro with more experience on these large systems could comment if that is out of line, but from what I have seen I don't think it is. I am curious what size rad vents do you have on the rads for the rear main? If you have too big of vents on those rads some of the first rads could be sucking up the steam before it gets far enough down the main. You want the entire main vented before the rads start getting steam. Then vent the rads slowly.

Controversial?

I have had people comment directly to me on that one that I was either wrong or they can vent some huge amount of main just fine with a single vent etc etc. Some just don't agree (I am not one of those people). I should add their logic is pressure...it's fine at 3 ounces or 4 or whatever. I am on the as low as possible side of things.

Fred

@KC_jones , my goodness. For 10 Gorton #2's he needs a good size vent pipe/tree to support those vents. I'm guessing he needs at least an inch to an inch and a quarter piping, unless he has multiple locations he can mount to.

KC_Jones

Fred said:

@KC_jones , my goodness. For 10 Gorton #2's he needs a good size vent pipe/tree to support those vents. I'm guessing he needs at least an inch to an inch and a quarter piping, unless he has multiple locations he can mount to.

With 105' of pipe on a single main that doesn't sound that outrageous to me. Also mentions having multiple venting stations along the main So I am guessing could break it down that way. By the Gerry Gill chart a 1" pipe should handle almost 5 #2 vents. I would think more like 1 1/2" pipe for 10? On a side note would you believe my little 30' main has a 1" vent tapping on it?! Crazy huh?

Fred

KC_Jones said:

Fred said:

@KC_jones , my goodness. For 10 Gorton #2's he needs a good size vent pipe/tree to support those vents. I'm guessing he needs at least an inch to an inch and a quarter piping, unless he has multiple locations he can mount to.

With 105' of pipe on a single main that doesn't sound that outrageous to me. Also mentions having multiple venting stations along the main So I am guessing could break it down that way. By the Gerry Gill chart a 1" pipe should handle almost 5 #2 vents. I would think more like 1 1/2" pipe for 10? On a side note would you believe my little 30' main has a 1" vent tapping on it?! Crazy huh?

I have a 50 ft. main with a 1" tapping on it too. Naturally it is bushed down to 3/4" but that's still works. I was just floored, thinking about 10 Gorton #2's on one main but that's the way it calculates.

KC_Jones

I didn't bush mine down...I had a bunch of 1" black fittings laying around though so that was my primary reason. It drains condensate back nicely.

JStar

Here's my rule of thumb chart for vent antler sizing:

1/2" = 2 Gorton #2
3/4" = 3-4
1" = 5-6
1-1/4" = 7-10
1-1/2" = 11+

BobC

Would it be better to use a steam trap as a vent if he needs that many Gortons?

Bob

JStar

The practicality of multiple Gorton #2 vents seems to be in the 10 range. Anything more than that, and it makes a whole lot of sense to use traps. Though, the traps have no means of stopping water, if it ever backs into the mains.

JStar

I don't like the idea of having an electrical failure leading to a massive steam leak.

The Gorton's work very well at low pressure from my experience.

Thermostatic traps solve the problem, and vent twice as fast, but at twice the cost.

archer874

Ok...I'm not sure how to approuch the problem.All the radiators on the front of the building have MOM #4 air vents and both left and rear mains and caped ...no air vents and the front of the building is at 80 degrees .The first 50' run in the rear which is 3'' has 4 # 2 Groton..The next 24' which is 2 1/2'' section has 1 #1 Groton and the last 28' section which is 2 1/2'' has 2 #2 Groton ...maybe I need more??? ...I installed a 1lbs to 5 lbs gauge which reads ounces but i never see it move at all , the boiler seems like it just can't or doesn't build any pressure .
How can i increase the pressure to a few ounces ...on the right rear of the building i also have #4 and #5 air vents on all the radiator....How much more can I choke this system?

KC_Jones

Just out of curiosity which way is the building oriented? Is the front facing south by chance? Did you add more vents already? This post is stating different venting from your original. Have you timed the movement of steam through the mains? How long from a hot header to the end of the main to be hot? If it isn't reaching the end of the main how far does the steam go and how long does that take? If the front main has no vents it should be getting much steam at all, just what the rad vents can let in. You don't really want any pressure...the lower the pressure the better. Could you post some pics of the venting? Are your mains fully insulated for the entire length? A drawing showing the layout of the mains would help a lot also.

BobC

If you find the main only gets hot for X feet check to be sure the slope of the main has not reversed in the area that is not hot. Pooling water will collapse steam and it might not make a lot of noise while doing so.

Bob

archer874

I did add a few more vents in the 3'' pipe ....the steam gets to the end of the second run within a normal time ...I will check it later...it seems to loose everything in the last 28' ...that where the rads start to take off ...those rads also have #5 and #6 air vents nothing to large ....how can test or check the boiler out put...BTU ????

Fred

Steam will take the path of least resistance. You may need to step back and try to figure out why it wants to go to the front of the building first and faster than the rest of the building. Are there so many large radiators on the front of the building with large vents that that main is actually out-pacing the other mains that have good venting on them? Or, are you filling the radiators in the rest of the building so quickly that those radiator vents are closing too early, making the path of least resistance the Front main with all of its open radiator vents? The Front main needs to be vented like the others and then start slowing the radiator venting down on the front of the building.

archer874

I also checked the pitch of the last run with a level and it does have a slight downward pitch toward the return. I thought it was enough for condensate to run in the right direction....should I drill a hole in the pipe and try to look inside to see if there is any water pooled up ???

KC_Jones

archer874 said:

the steam gets to the end of the second run within a normal time ..

What do you define as a "normal time"? That is very subjective. An actual time is more useful to judge what is going on. I wouldn't go drilling holes in pipes at this point. It's not just pitch on long runs like that you need to have enough support so there aren't any sags. If you have a sag you will measure slope in both directions on the same pipe depending on which side of the sag you check. Along with using a level a good string line can go a long way to checking for sags. Run a string line along all the runs you can see and make sure they are straight. You can also use a string level and kill 2 birds with one stone. Run the string below the main a fixed distance, level the string then use a tape measure and measure up to the pipe. It should get closer to the string as you move away from the boiler. If at any point it moves closer then further away that is a sag and needs fixed. Remember buildings can settle over time and things move around.

ChrisJ

JStar said:

I don't like the idea of having an electrical failure leading to a massive steam leak.

The Gorton's work very well at low pressure from my experience.

Thermostatic traps solve the problem, and vent twice as fast, but at twice the cost.

If you use a normally closed solenoid and a thermal switch that opens with heat this wouldn't be an issue, it just wouldn't vent without power.

Solenoid and switch are wired in series and powered by the thermostat.


Is it less reliable than normal vents? I have no idea which is one of the big reasons I haven't done anything yet.

archer874

The advise about the venting was good ..Originally I had only one Gorton #1 on the 50' 3'' main hoping to push all the steam to the left side of the building ...Now that I added a total of four #1 Gorton 3/4 main vents the steam get's to the end of that run in 5 minutes after the boiler has been off for an hour ..I am happy about that... much faster then before .The steam also gets to the other side much faster, the entire 100' main fill's up in about 10 to 12 minutes...that never happened before , It seems that the 3'' 50' section of the main from the boiler had a lot to do with that , It needed to be vented real bad tomorrow I will add a few more vents to it to see if I can bring it around even faster or stronger...The next step is to try to vent the front and rear mains at the same pace...balance????
That being said I really like the Groton #1 main vent maybe better then the #2 ..The #2 cost me 80 dollars and the #1 cost me 21 dollars, I can buy four #1 vents for the same price ....does anyone know how many #1 equal the vent rate of the #2 ?

Fred

It takes about 4 Gorton 1's to equal a Gorton 2

KC_Jones

To equal the 10 #2 vents you need for one of your mains will take exactly 33 #1 vents, by the numbers. And then you have to mount 33 vents...with fittings. The #2 ends up cheaper when you count fitting cost.

Steamhead

The most important thing here is, you need all your venting capacity at the very end of the main.

My calculations show the 3" pipe contains 2.76 cubic feet of air, the first 2-1/2" has 0.72 CF, and the last part of the 2-1/2" has 0.84 CF. That's 4.32 cubic feet total.

A single Gorton #2 will vent 1.1 CF/hour at 1 ounce pressure. So, you need 3.93 #2 vents on that main. Since they don't make vents in fractional sizes, you'd start with four of these vents, all of which should be mounted at the end. You can always add more later if needed.

archer874

I have two at the end now and one 28' back at the elbow ...I will probably add one more . I am happy about the time that it takes for that main to vent the air out and fill with steam, I still have a problem though with the radiators they only get hot half way up even if I take the air vent out ...I made sure the radiators are pitched toward the shut off valve ..could the air vent size have anything to do with that ?

KC_Jones

Is the thermostat shutting off the boiler or is it firing and they aren't filling with steam? Most of the time they will only partially fill with steam as you don't generally need full output unless it's frigid outside.

Abracadabra

archer874 said:

I have two at the end now and one 28' back at the elbow ...I will probably add one more . I am happy about the time that it takes for that main to vent the air out and fill with steam, I still have a problem though with the radiators they only get hot half way up even if I take the air vent out ...I made sure the radiators are pitched toward the shut off valve ..could the air vent size have anything to do with that ?

What are you venting the radiators with? Do not vent any radiator with anything over a MOM/Gorton #4 or a hoffman 40, especially on the riser you are having problems with.

nicholas bonham-carter

It looks like you could still add some more main venting. Remove the vents at the end of the longer main, and fire the boiler, stopwatch in hand, and see how long it takes. My guess is one minute for each 20 feet would be a realistic result. Then add enough main vents to equal that speed. While you are gritting your teeth over the price of the vents, look at your fuel bill, and calculate how much an extra few minutes of burner time is costing, times 20 times a day, 7 days a week, 5 months a winter.
Main venting is an investment, and not an expense.--NBC