Steam boiler lines: am I over venting ?


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Old 10-04-19, 06:12 PM
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Steam boiler lines: am I over venting ?

I have a steam boiler that has 2 main runs. Each main is about 30-40 feet to the end. On the end of each main has a 3/4 nipple with a big mouth vent on each. Im thinking about making an antler and adding another big mouth, making it 2 big mouth vents for each of the 2 mains....

would that be over venting???

The reason im doing this is because my first floor heats sufficiently and satisfies the thermostat before my 2nd floor is fully heated. The 2nd floor radiators has large capacity air valves and the 1st floor has all the air valves closed to the lowest so they heat up slower...

But the 2nd floor still heats only.half way when the cycle shuts.down...

Would venting the mains more help.in my situation???

Thanks for your help.
 
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Old 10-05-19, 05:41 AM
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Is this system a 1 or 2 pipe steam system? If you do not know the difference, then how many pipe connections are on each radiator? Do the 2nd floor rads each have their own take-off steam line tied to the basement main feed line? If you have both 1st and 2nd floor rads tied to the main feed then adding extra main vents will not solve your problem. Pictures and/or a drawing of your system and the radiators would be helpful. Has any work or changes been done to the system? Do you know if it ever heated properly in the past? More information of your system is necessary.
 
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Old 10-05-19, 08:14 AM
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I have a 1 pipe steam system with 2 main lines from the boiler. Both of the main lines have big mouth vents on the ends. yES, both the downstairs and upstairs radiators are tied to the main lines....

I insulated all the piping, changed the pigtails, and added a new 1-5 psi gauge and added 2 big mouth vents to the ends of the main. It runs perfectly with no noise or banging whatsoever with low pressure steam. The only issue is that when it runs a normal cycle, the upstairs radiators only heat up HALFWAY when the 1st floor is fully heated and thermostat is satisfied.

When i bought the house, there was 2 tiny radiators upstairs so i replaced them with LARGER radiators for more heat.

Both of the upstairs radiators do heat up on a regular cycle, but only HALF WAY. I already used the largest air vents upstairs so the steam can go up faster, but its not sufficient. I use Maid O Mist size D vents upstairs which is the largest.

Since the radiators are so large upstairs, should i TAP an additional air vent on each of the 2 radiators?
 
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Old 10-05-19, 08:28 AM
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I'm not the pro here here but I'm thinking the pipe may be too small to support the bigger radiators.
 
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Old 10-06-19, 04:47 AM
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I see that you asked the same question on "heatinghelp.com" . Great, since that site is mainly for steam boilers and a lot of experienced guys monitor that site. @ PJmax may be right. What size piping is feeding the top floor rads, how big are the rads, what size valves did you use at the rad inlet? Are the rooms downstairs evenly heated? If you can't correct the problem without completely rebuilding the piping system, you may be able to correct the problem by adding "Danfoss" or similar thermostatic valves to the upstairs rads. You can go to a web site like "supplyhouse.com" or just search for "thermostatic valves for 1 pipe steam rads". This will give you some control of the temp in each room. The room with the thermostat will have to remain as is since the boiler has to cycle off the thermostat for the rest of the rad thermostats to work properly and make sure that the thermostat is in the coolest room. If the room with the thermostat is not the coolest room, consider replacing that rad with a smaller rad so that room is the last to be satisfied with heat. Hope this helps.
 
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Old 10-06-19, 06:10 AM
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I think i found my answer.

THANK YOU STEAMBOY....

I will try the Danfoss Valves on the 1st floor room with the thermostat and turn it all the way to lowest so it heats up super slow.

Im guessing this will give the boiler more run time so the upstairs will fully heat. Im gonna try like 2 x of the danfoss valves first on the rads right next to the thermostat.
 
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Old 10-07-19, 06:09 AM
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@ Thumbs; my advice for the "Danfoss" valves would be to install them on the rads in the rooms that get the hottest. The wall thermostat should be in the room that is the coldest so the boiler runs until that room is satisfied. By the time that room is satisfied all the other rooms have heated to your desired temp. The way these work is by controlling the air bleed so as to control the heat output of the rad. I always used these only when I could not balance the system as a customer wanted or that the customer wanted some control of the heat at every rad. They are not a perfect solution, but they do work. Some residential steam guys don't like to use these valves because they believe that there is always a solution to uneven heating. I spent 40+ years in the heating business, a lot of it on commercial buildings so I think I know a little about steam systems. The fact that you said that the steam lines to the 2nd floor are 3/4" just like the1st. floor may be part of the problem. those lines probably should a size bigger to increase the volume of steam to the upper rads. Remember this; these old steam systems were usually not designed to be used with an on/off heating boiler. They were in most cases designed to be used with a coal fired boiler so that there was no shut off of the system by a thermostat. Once the coal was lit the steam system system was active all winter. Today, nobody wants to use a dirty coal boiler so they install a gas or oil burner that runs off a wall mounted thermostat. One last thing, you should get the gas input checked or you can do it yourself by clocking the gas meter. (1 cu ft per minute = 60,000 btu/hour) Turn up the thermostat and make sure that only the boiler is running for an accurate reading. My 2 cents.
 

Last edited by Steamboy; 10-07-19 at 07:26 AM. Reason: more info
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Old 10-08-19, 05:19 PM
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Question.......Why do the rads have to heat all the way across on the second floor? I have not seena complaint of not enough heat since you installed larger rads.
The question was asked earlier what size pipe goes to the second-floor radiators. Are the radiators over 25 sq. ft? If so, a second vent would help. You would have to drill and tap a connection below the existing vent. Te existing vent is about half way up the radiator opposite the valve end correct.
 
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Old 10-09-19, 03:35 AM
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If you want to double up on the rad vents, why not install a short 1/8" nipple and a tee and install a rad vent in each of the 2 remaining ports of the tee? I did this many times. It's crude but it can be done.
 
 

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