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Radiator sizing


I own a 3 family with 3 floors each with a 3 bedroom apartment.  The heat is single pipe steam with a thermostat on the 2nd floor.  In order to get he 3rd floor warm I have the 1st at 85, 2nd at 75 and 3rd is 65.  The apartments are identical and I was considering taking the 6 section and 8 section on the 1st floor living room and dining room and moving them to the bedrooms on the 3rd floor and moving 2 4 section readiators down to the 1st floor. 

My thought process was the smaller radiators would come to temp and shut off and I would have more steam going up the the 3rd floor.  The larger radiators would provide more heat where I need it.

I have replaced all the valves with adjustable valves and opened up the valves on teh 3rd floor and turned the ones on the 1st and 2nd way down.  This helped but did not solve the problem.

Other info:

1 The pipes have no isulation on the verticals (visible in the apartments) or the manifold that runs around the basement.

2) the HOT 1st floor living room / dining room are right above the boiler so they get the steam 1st

3) 50 year old oil fired boiler with updated maintenance

4) total sq footage approx 3500 sq ft

5) Hot water is off the boiler

6) Location Massachusetts

Long term I would like to install 3 separate gas fired heating systems and have the tenants pay for thier own heat.  Unfortunatley I do not have the budget for it today.  Hoping to cut down on teh oil consumption as I am burning about 3500 gallons a year.




  • Paul48Paul48 Posts: 4,158
    edited September 2012

    Have you looked at thermostatic radiator vents?Is gas available to the home?
  • main line venting and a vopourstat

    If you get the fire rate down to match the load and you use a vapourstat to keep the pressure low you most likely will get a more even distribution of steam. Thermostatic valves also help. Incase you were wondering, yes I service your area of Mass.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Uneven heat

    When first installed, your system was evenly heating all floors. Don't switch the radiators around before checking the main venting, and pressure. Your task is( should you decide to accept) to bring your system back to its original state of operation. The original installers would have made those radiator switches if they were needed, and they were not.--NBC
  • Balance the venting.

    Moving larger radiators upstairs, apart from being dangerous, won't do you any good unless the supply pipes are adequate. I'm guessing they're not, because they weren't there when the system was built, and it's probably not just because they didn't want to lug the all that way.

    My hunch is that, at some point, someone replaced radiator vents and put the same size vent on every radiator, or they could have just been arbitrarily replaced with the wrong sizes over the years. At any rate, venting is the easiest thing to screw up. The dead men who designed and built that heating system probably knew what they were doing. The same can't be said for every Tom Dick and Harry who has replaced a radiator vent over the years.

    As you know, the vents on one-pipe radiators allow the air to escape to make room for the steam to enter. The second and third floor radiators may also need to vent the air from their long supply pipes too, so they need more venting. The farther you get from the boiler, the more air you need to vent, and pay particular attention to any radiators that are located near a thermostat. If there is a large radiator near a thermostat, the heating cycle ends once that radiator heats up the air in that room. You need to make sure that every other radiator is full of steam before that happens, so use the slowest vent you can find on this one.

    A good place to start might be to post pictures of your radiators showing their vents and indicating where each is located. We can help you identify them and recommend which ones to replace or exchange. You'll find moving vents around a lot less backbreaking than moving radiators.
    1983(?) Peerless G-561-W-S
    3" drop header, CG400-1090, VXT-24
  • vents

    I replaced all the vents with adjustable vents.  I have all the vents on the 1st floor almost off, the 2nd floor at about 30% and the 3rd floor wide open.  When that did not fixe it, I drilled the hole larger on the 3rd floor vents to allow for more airflow.  The vents are the adjustable ones available from Home Depot.  I also shut the valve on the radiator near the thermostat just to slow the heating of that room.

    Thanks for the advice on not moving the radiators.  I am not going to do that as I was dreading moving the 8 section up 2 flights of stairs and I found the pipe / shutoff to be sized smnaller so the connection tot he radiator would need to be changed and I am not up for that again.

    Regarding the design the 3 floors are identical so the only way I see that they could be different is in the vents.

    Thanks for all the help!
  • Paul48Paul48 Posts: 4,158

    Bringing Charlie in would be paid for in savings this heating season, and everyone would be comfortable.
  • Scrap or return your vents

    Driling will do nothing except wreck the vent. You need Brand name vents. After you get either Gorton vents sized for the radiators or Vent Rite 1A's on all the radiators then you can start looking at the rest of the system. Can you post a few photo's of the boiler and piping around it?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Vents

    If your adjustable vent is a USAV 884, that's just an 883 with a variable shutter that lets you throttle it down. The orifice is about .115–.116", which puts it somewhere between a Gorton #6 and C. I'm not sure if drilling out the outer hole will increase the venting rate. When they get clogged you normally won't see scale obstructing the hole, but soaking the in white vinegar overnight clears them out, which suggests that the real orifice is inside. I also don't believe the shutter is capable of completely closing the vent.

    I think the fastest vent Home Depot sells is the Maid-O-Mist D, which is comparable to a Gorton D, but not quite as fast as a Gorton #1.

    Don't try to make sense out of the model numbers, but the Gorton vents are, from slowest to fastest, #4, #5, #6, C, D, #1 and #2. (#2 is for main venting only.) If you start with #4s on the first floor and work your way up to a #1 on the most remote third-floor radiator you'd be exploiting the full range of available venting.

    Regarding the supply pipe sizes, this would not just make it necessary to change the fittings on the radiators. A 1" supply pipe should only be used on 24 ft.² EDR or smaller radiators. The bigger the radiator, the faster it turns steam back into water, and in a one-pipe system, the steam and water rub elbows at the valve and all the way down the supply pipe, so you might find that lugging those big mamas upstairs just gives you more noise instead of more heat.

    By the way, I assume you checked to make sure that all your valves are turned fully on.
    1983(?) Peerless G-561-W-S
    3" drop header, CG400-1090, VXT-24
  • SteamheadSteamhead Posts: 11,161
    Main Vents?

    do you have any? If so, what kind? How long is each steam main, and what pipe size?
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • I'll second that.

    Charlie and the other pros on this site have been such a big help to me whenever I needed it. Clearly they would not be here if they didn't truly love what they do and care more about helping people than making a quick buck.
    1983(?) Peerless G-561-W-S
    3" drop header, CG400-1090, VXT-24
  • Have any radiator valves been change?

    I see more frequent use of water radiator valves on steam systems here in Mass. Central Mass is the epicenter for this right now.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • RodRod Posts: 2,067
    edited September 2012
    Enhanced photos

    Hi- I tried to enhance the photos a bit so that the piping was more visible. I did a blow up  a section of the second shot where it seems there may be Main Vents (?)

    - Rod
  • vents

    Yes, those are the vents, there are 2 of them. The manifold runs in 2 directions around the basement and that is where they come back to the boiler.
  • nicholas bonham-carternicholas bonham-carter Posts: 6,482
    edited September 2012
    Main venting

    Try putting on some gorton #2's in place of what you have there now and see if there is a difference in the speed with which the steam fills the mains. The main vents do all the work, and cannot be replaced with r adiator vents modified with home-brewed drilling out. This one area in which saving money will cost you plenty in the long run!

    You should have the steam arriving at the radiators on each floor simultaneously, with th e top floor not lagging appreciably behind the lower floors. Bigger radiator vents, such as gorton d's may help get the steam up the risers more quickly.

    A good low pressure gauge will tell you how many ounces of back-pressure are produced during the main venting phase (2 ounces is good).

    When you economies on main vents, the money saved will immediately be taken by your fuel company, in the extra fuel burnt to squeeeeeeeze the air out of the constipated little openings of cheap main vents. You may need a menorah of several vents for each line if your pipes, and boiler steam chest are large.--NBC
  • Vents

    OK so now I am more confused. are we talking about the 2 vents in the basement on the manifolds or on the radiators themselves?

    Last winter I removed the vents from 2 radiators on the 3rd (top) floor and still the 1st and 2nd floor filled up and the boiler shutoff before I got steam to fill the 3rd floor radiator. I get 2 of 6 sections to warm up but by then they 1st floor is a sauna and the 2nd floor is at 75 and the thermostat (on 2nd floor)shuts off.

    I am sure you are correct that the vents I bought are not working because they do not seem to slow the 1st floor at all. I need some other work done so I think I will have the system evaluated in case there is another problem.

    The house is in Clinton MA, are any of you close?
  • RodRod Posts: 2,067
    Steam Vents

    Hi Chuck-

    On venting there is an old steam adage- "Vent your mains quickly and your radiators slowly!"  A steam system has two type of vents.

    1. Main Vents - which are high capacity vents. They allow air to escape quickly from the steam mains so that the radiators all receive steam at approximately the same time.

    2. Radiator Vents- While they may work on the same principle, these vents are made especially for radiators. They control the speed at which air is able to leave the radiator.

    Controlling the speed of the air leaving the radiator controls the speed of the steam entering the radiator.  The whole idea is to achieve ."balance" which means all the radiators heat to the same percentage at the same time. For one reason or another your system is way out of balance. Having rooms overheat is tremendous waste of fuel!

       As others have suggested, it he is available, it would be an good idea to get hold of Charles Garrity. He is a very experienced steam pro and would be able to straighten your system out so that it would heat evenly which means it would be more comfortable and more economical.

    - Rod
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