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Speed of radiator venting

sean_bsean_b Member Posts: 31
Hi Guys, hope you all had a great summer. I was a frequent contributor here last winter when I bought my first place that had steam heat. You all helped me a ton troubleshooting and getting my whole system functioning properly - it was a total mess!

Well... I recently turned my heat back on and here I am again!

Actually... all is running quite well thanks to you guys. I just have a quick venting question for the vents on the radiators - they are adjustable Ventrites (#1's i think?).

In Dan's book, and elsewhere on this site I came across the following:

"Vent large radiators quickly and small radiators slowly no matter where they are in the building. Focus on the air content of the radiator rather than its location in the building.If your main vents are working, steam will arrive at each radiator at about the same time."

This makes sense, but my problem is I have two large radiators in the living room, where the thermostat is also located. The thermostat seems to shut off too early and leaves a lot of the house more chilly. Should i close those living room vents down considerably and increase the venting in the vents in the chillier rooms wider (according to their sizes)? Is this going to mess up balance and flow of steam?

Thanks in advance for any help you can offer!


  • RodRod Posts: 2,067

    Hi- There is also another adage : "Vent your mains fast and your radiators slow! You're going in the right direction. Venting a big radiator quickly will fill the radiator completely with steam. This steam then collapses (condenses) and forms a huge vacuum which pulls in even more steam and this continues till the room warms up and the condensing slows down.  As there isn't an unlimited amount of steam available, these big "Hungry " radiators consume large amounts of steam which tends to starve the smaller radiators. You may find that when you slow down the venting on the large radiators, that you won't then have to increase the venting on the smaller ones as they are now getting their fair share of the steam.

    - Rod
  • Big-AlBig-Al Member Posts: 263
    edited November 2011
    Why not?

    I have two big radiators nearest the thermostat.  I vent them more slowly than others. The house seems to heat more evenly that way.


    I also think, within reasonable limits, it's perfectly acceptable to put faster vents on radiators in cold rooms, regardless of radiator size.  In my old house with forced air heat, I adjusted  the duct dampers to try to get the house to heat more evenly. We want our homes to be comfortable, right?  Why not try to get more steam to cold rooms? 

    OK, in a perfect world, all radiators and heat registers/ducts would be properly sized for the rooms they are located in . . . but most of us are pretty well stuck with the radiators we already have . . . ideally sized or not.   
  • BobbyCBobbyC Member Posts: 96
    same issue

    i have smiliar issue to sean and trying to "fine tune" my rad venting since installing new gorton main vents.

    Al, when you say slow vents what type are u using?  2 of my biggest radiators in my house are located somewhat near my tstat; living room (tstat located) and dining room.  

    Wife thinks i lost my marbles as i go around feeling radiators when the heat's running.  hahaha
  • Big-AlBig-Al Member Posts: 263
    edited November 2011
    Number Five

    My big radiators near the stat have Maid-O-Mist #5s (.070" hole) if I recall correctly. (Gortons are numbered similarly.) A #4 vent is even slower, but I had fives in my collection.   Our upstairs bedroom could really use a bigger radiator, if one would fit.  It has about a size D (.1850") vent, and it is fully hot before the big radiators warm up much at all.  I tried super-fast VeriValve vents upstairs at first, but they vented so quickly that the radiators would gurgle and spit.

  • malexmalex Member Posts: 104

    I am considering replacing old vents with Varivalves so that I can balance and potentially fine tuen the heat in certain rooms (I too have noticed that the living room gets up to 70 before some of the radiators in other rooms even get hot).

    Anyone had any luck with the Varivalves or is it better to stick with good quality fixed vents. Any recommendations?
  • BobbyCBobbyC Member Posts: 96
    Thanks Al

    I actually put a maid o mist 5 on the big one in my dining room too and she gets hot quick.  Put MOM D's on 2 bedrooms where before they took awhile to get hot and they seem to get too hot too quick so I dropped down to C's there. 

    the search for eternal balance continues.  
  • Big-AlBig-Al Member Posts: 263
    edited November 2011
    VariValves . . . no . . .

    Because of the way they are made, Varivalves seem to gurgle and spit a lot. Even when they are nominally closed, they still vent pretty fast. 

    I like the Maid-O-Mist vents for experimenting. The vent orifices are removable. You can install #5s or even #4s everywhere, and if you want a particular vent to work faster, you can unscrew the orifice and drill it out a little bigger. Or, you can buy a variety of vents and swap around the orifices until you get the balance you need.

    Adjustable vents are OK too, like the Vent-Rites, as long as nobody starts fiddling with them behind your back.  I also still have a couple of adjustable Watts radiator valves.  That's what I tried first.  They work fine, but they close with a loud clank and can really whistle when the system goes into vacuum at the end of a heat cycle.  They are still in a couple of rooms far from where I sleep, so they don't bother me much.
  • Big-AlBig-Al Member Posts: 263
    edited November 2011

    My room-to-room balance isn't perfect either, but it's a lot better than it was.   I just leave all the doors open most of the time and things seem to even out pretty well.

    If the #5 is too big, you could solder the orifice shut and re-drill it smaller.  I did that on one I drilled out too big.  Or you could just buy a #4.  They're not horribly expensive compared to some other brands.
  • Hoffmans?

    So what is the opinion of the elder about Hoffman 1As? I have replaced almost all vents in 13 radiators with these beasts (6 for $100 is a fair deal IMHO) and they seem to do the job quite well. They are not fool proof, you need to be careful when adjusting the venting hole, but they are solid and quite tampering resistant, too.
  • Big-AlBig-Al Member Posts: 263

    The Hoffman vents should be very good.  I prefer Gorton or Maid-O-Mist vents myself.  They operate slowly.  Any alcohol based vent like Hoffman, Dole or Watts is going to snap open and shut with an audible clink.  It bugs me some, but maybe I'm just neurotic.
  • Convector vents?

    Thank you Al. What is the difference between radiator and convector vents, are convector vents faster? I have one 1/4" convector vent (Hoffman 1B) installed on my largest radiator upstairs and it seems to get the job done just fine.
  • Big-AlBig-Al Member Posts: 263
    edited November 2011
    Convector Vents

    As far as I know, the only difference is that convector vents are straight and radiator vents have 90 degree connections.  I think that convectors are very low-slung and their vent tappings are on the top instead of on the side.  If it is on a radiator, I assume it's mounted on an elbow?
  • Directly on top

    My radiators are a mixed breed of radiators and convectors. Heavy duty, cast iron, thick ribs but recessed in walls behind heavy iron grates. They have holes for vents on top so the convector vent is be mounted directly (via 1/8" -> 1/4" coupling), I need elbows to use angle radiator vents.
  • sean_bsean_b Member Posts: 31
    thank you!

    Thanks Rod and Big-Al. I'll slow the vents in the living room down and maybe vent the others according to their size and fiddle a little.

    by the way my wife thinks i am nuts also BobbyC! I run around the house timing all this stuff - timing when main vents close, touching radiators, making notes, etc. hahaha
  • Big-AlBig-Al Member Posts: 263
    It's a serious affliction

    to have steam heat.  it took me three heating seasons before I was satisfied that everything was adjusted right.
  • Dave in QCADave in QCA Member Posts: 1,660
    Also Aflicted

    I routinely check my cast iron hot water radiators at home.  The temperature is an indicator of how cold it is outside.  I am always feeling the steam radiators at the apartment building.  But, paying attention to them has paved the path of resolving problems that the previous owner was oblivious to.

    In the summertime, I walk around and put my hands in the air and feel for the draft coming from the central air.  I try to direct the airflow in a manner that will disperse the air evenly and get  the air to the far side of the room.  And, I have to check it evey now and then to make sure its still OK.   

    I have learned to laugh at myself.... and others have learned to appreciate the fact that their HVAC systems will always we working perfectly when I am around.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • KbalzKbalz Member Posts: 53

    This thread has great information, I am in a similar situation. Thanks.

    Also, Bobby, - thanks for the chuckle, my wife and two year old said similar comments to me last week! She keeps asking me if I found it yet?
  • SFlashSFlash Member Posts: 1
    vent-rite rad valves

    Been scanning the comments all appropos to my heating system. I'm the one who checks all the radiators in my house (Mom whose husband knows nothing).

    I see nothing about Vent-Rite adjustable valves. That's what my local supplier and my heating company sell most. Any opinions on that type?

    Had an overflow of the boiler and one steam radiator. Was told it was recommended to replace ALL valves as a result. Won't go into all the balancing issues. Appreciate the comments here.
  • BobCBobC Member Posts: 4,408
    Very good

    The ventRite #1 is a very good vent, they are expensive but they last forever. You may occasionally need a vent that is a bit faster then they are but for most the ventrite is a good choice.

    I have a couple of 30+ year old Ventrites on my system, all the rest are Maid O Mist.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
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