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uneven heat

Hey guys, had a new steam boiler installed last season, worked great.  This past summer, I pulled out all my radiators and sandblasted/painted them and put them back.  When I turned on the heat this year, some got hot, some didn't, the boiler was noisy and surging.  I thought maybe I ruined the air valves by having them outside half the summer, so I replaced them.  The old ones were all screwy anyway (but somehow worked):  a lot of Groton "D"s, including one in the thermostat room, some adjustables.  I bought all Groton's.  #4 in the thermostat room, #5s on the rest of the 1st floor, #6's upstairs, and #C's in two cold, far-reaching upstairs rooms. 

When I ran the system like this, it was worse.  So I removed all the air valves and ran the system until each radiator got hot, then inserted the valves.  There seemed to be a lot of air in the system, if that's possible.  It's quieter and working slightly better now, but not great.  What else can I do to get even heat?




  • uneven heat after radiator painting

    i would check your main air vents for functionality. they do 90% of the work of air removal, and are almost more important than the radiator vents, as far as sizing.

    keeping the pressure low oddly also helps with air removal, and a good low pressure gauge [gaugestore.com 0-3 psi]  will show you what that is. if it is too high, the pigtail may be clogged, preventing the pressuretrol from seeing the pressure.

    the boiler may need "skimming" as all the oils of pipe threading, and installing, may finally have found there way into the boiler.

    also check the thermostat anticipator, if it is non-digital. more info on all  this can be found in "the lost art of steam heating" available from the shop here.--nbc
  • Unknown
    edited November 2009
    Air in Steam System

    Hi Tom- Air in your steam system when it's not running is normal. The reason you have vents on your mains and vents on your radiators is to allow the air to escape. If the air can't escape, it stops steam from entering the radiators. I'm assuming that since you have vents on your radiators that your system is one pipe steam. Since you have removed the radiators, it is important to make sure they are now sloped slightly towards the end where the steam pipe is attached. This only has to be a slight slope so the condensate (water) will drain back from the radiator into the steam pipe. I use quarters coins as shims to see to how much I need to shim each radiator and then replace it with a piece of hardwood or hard plastic of the same size. Use a carpenter's bubble level to determine the amount of slope. Measuring isn't reliable especially in older houses where the floors may have sagged. Too much slope can cause problems so try just a little at first. Just enough to help the condensate drain out.

    If you don't have a copy already I would suggest you get a book called "we Got Steam Heat!" which is available on this site. Here's a link to it:


    It is also available as a package with another excellent book on residential steam heating "The Lost Art of Steam Heating" You can get these books separately though I'd recommend the package. Here's a link to the package:


    I constantly recommend these books as from personal experience I know what a benefit they can be to someone who is new to steam heating. The books are easy reading, humorous and packed full of facts, explanations and illustrations on steam heating. In a few evening's reading you'll know a lot more about your steam system. The books have paid for themselves many,many times over.

    As Nicholas mentioned your system sounds like it needs to be skimmed. There is a good article on skimming in the June 2009 issue of Oil Heating on Page 20  called "Cleaning a Steam Boiler and Keeping it Clean"


    It would also sound like you may have an issue with your main vents. Have you checked them for proper operation?

    - Rod
  • speedsk8r27
    speedsk8r27 Member Posts: 3
    thank you

    When I was ordrering the air equalizing valves, I noticed that there were vents on the mains; I have no idea where they are, and I followed the pipes along as far as I could.  I'm going to get a level and see if I have slope in all the radiators.  The system worked well last year, and I put the radiators back the way they were, and they were not shimmed.  Skimming sounds interesting -- but not something I would attempt myself.   After reading the article, I'm convinced the guy who put my boiler in didn't take the time to clean it before firing.

     I'm in NJ (08876), is there a directory of local steam boiler professionals I could access?  Thank you for all the good information.
  • find those main vents, whever they are!!

    you will get a lot of improvement from increased main venting. they are normally found where the dry return turns down towards the floor to the wet return [in a paralell-flow system], and as i said before, they are the most important air removers in the system. if they were never installed, it would be worth the cost of instalation, for the benefit they provide, as the steam cannot rise until the air has "been shown the door"--nbc
  • Unknown
    edited November 2009
    Skimming is easy

    Hi Tom-  For a steam pro look at the top of this page at "Find a Professional"and see if you have one located near you.

    Skimming is really easy. You might want to get a pro to install a skim port for you. (See the attached drawing) as sometimes getting the plug out of the boiler port for the first time can be a bit of a hassle. Look in your boiler's Installation &operating manual as they usually designate where the skim port is located.

    As i said skimming is easy and one of the reasons you want to do it yourself is that it is expensive having a pro standing about waiting for the boiler to skim and you'll usually do a better skim job than a pro as they hurry the job as they feel conscious just standing about.  If you are worried about the procedures of hot skimming just do cold skimming.(A lot of people think cold skimming is better anyway)

    How you cold skim - With the boiler cold (cool) open the skim port and place a 5 gal. plastic bucket under the port to catch the runoff. Open the fresh water valve supplying the boiler and slowly flood the boiler till the boiler water runs out the skim port. The water should just trickle out- the slower, the better. I fill the 5 gal bucket in about two hours so that should give you an idea of how slow it should be. After you have finshed skimming close the skim port and turn on the burner till the boiler makes steam. You should ALWAYS boil the boiler water after you add fresh water to the boiler as the heating drives off dissolved oxygen which can damage your boiler. You may have to repeat skimming several times till you get a "happy" no bouncing water level. Let the boiler run a day or two between skimmings

    - Rod
  • speedsk8r27
    speedsk8r27 Member Posts: 3
    sounds easy enough...

    I will look up the skim port in the manual, thank you.  Just as a follow up, I drained and refilled the boiler yesterday, ran it, and the system operated perfectly.  Is this more evidence that skimming is needed??  I mean, there was no noise, the water level stayed constant, the radiators heated up the way they should.  And it's not like tar came out of the boiler either, just some tea-colored water.
  • If it's working don't fix it!

    If it's working to your satisfaction don't mess with it!  I guess you could say "you skimmed through the bottom of the boiler".  You might have to skim in the future if more crud works its way into the boiler water but now, with a steady boiler water level, you're fine.

    - Rod
  • Dezso3
    Dezso3 Member Posts: 11
    Overheated rooms

    My house has a steam heating system, and ever since I have lived here, one of the rooms in the house has always been overheating. While the thermostat in the dining room is set to 70 degrees F, the temperature in the second floor room I mentioned is about 80 degrees. The overheating is exacerbated when it gets really cold outside, especially below 20 degrees F. The radiator in the room is 24" tall, 20" long, and 4" wide, has a Gorton No. C vapor equalizing valve. The room itself measures about 10 x 12 ft. It seems that the reason that the room is overheating is because the bottom floor is so drafty that it takes longer to heat up than the second floor, resulting in uneven heating. However, I am not sure :/
  • Unknown
    edited December 2009

    I'm assuming that having vents this is a one pipe steam system/ There are a couple of ways to reduce the heat in the room. You could try using a slower vent that the one you have now, the Gorton "C".

    The other method that works very well is to use a TRV on the radiator. For a one pipe steam system you need to use a TRV with a vacuum breaker. Besides the TRV you may also have to get a straight (not angled) radiator vent to fit the TRV. The Danfoss TRVs are adjustable from 42F to 85F.  You can get these Danfoss units on the internet from Pex Supply. - Rod


    Edit: Just as a suggestion - In the future, use the Orange Button,"+ a New Thread" at the top of the beginning Strictly Steam page to post your question as tacking in on the end of an older post like this one, it might be missed and you wouldn't get a reply, - Rod
  • uneven heat between 1st & 2nd floor

    it might be a good idea to start a new thread for your question, so it doesn't get mixed up with this one.

    can you determine whether the steam is arriving at all the radiator shut-off valves, for that is the goal. you could do a test after a cool down period with your helpers and fire the boiler. have the helpers shout out when the valve is steam hot and make a note of which areas get steam before others.

    this could be a lack of main venting, incorrect pressure, or missing insulation.--nbc
  • jpf321
    jpf321 Member Posts: 1,568
    that TRV manual....

    that TRV manual has a bunch of good info for rad troubleshooting, system pressure, etc. it's obvious they read the TLAOSH :-)
    1-pipe Homeowner - Queens, NYC

    NEW: SlantFin Intrepid TR-30 + Tankless + Riello 40-F5 @ 0.85gph | OLD: Fitzgibbons 402 boiler + Beckett "SR" Oil Gun @ 1.75gph

    installed: 0-20oz/si gauge | vaporstat | hour-meter | gortons on all rads | 1pc G#2 + 1pc G#1 on each of 2 mains

    Connected EDR load: 371 sf venting load: 2.95cfm vent capacity: 4.62cfm
    my NEW system pics | my OLD system pics
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