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Riser venting

I have and 1909 condo building in Brookline MA with a one pipe steam parallel flow system with two mains, both have step returns so four returns. I have the returns vented with big mouth's, three have one and the slow to heat return has 3. The mains are roughly the same length but the slow main feeds all of the large radiators in the living and dining rooms. Since I am venting on the returns, not the mains, would it make sense to vent the risers as well to get the air out of the system faster? It is a corner building I have Hoffman 40's on most of the radiators, the coolest unit has Ventrite No.1's. Heat is fairly even except on stormy days with a strong wind out of the east.

3 story building with a Burnham V904A, slightly over sized. Vaporstat set to 1.25 cut out 4 oz cut in.

I am just looking for ways to make the system more efficient.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 17,060
    Sure won't hurt to vent the mains... they should both have vents at the ends. It also won't hurt to vent a riser. I might ask, though, are the vents on the radiators properly sized? Sometimes on one pipe steam the problem isn't so much that some areas aren't vented enough as that others are vented too fast...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • gfrbrookline
    gfrbrookline Member Posts: 683
    Can't vent the end of the mains since they terminate in the ceiling of our basement unit. That is why the main venting is tapped on the dry returns.

    Since I am only using Hoffman 40's and Ventrite #1's in the cold rooms, two rooms out of 18, I don't think the radiators are over vented. My mains are roughly 40' of 2 1/2 inch so I think the big mouths should be adequate but would like to know if adding riser vents would help vent the air out and make the system more efficiently.
  • Jamie Hall
    Jamie Hall Member Posts: 17,060
    Riser vents will help. Probably a lot. But they won't cure the imbalance problem. Make sure that the cooler rooms have adequate radiator venting, appropriate to the size of the radiators -- and then try slowing down the rooms which get too hot. Also make sure the thermostat is in a reasonably neutral spot.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • gfrbrookline
    gfrbrookline Member Posts: 683
    Thanks, I have Vetrite #1's on the cool side and Hoffman 40's on the warmer side. I don't think there is anything that will vent slower than the 40's. The thermostat is a VisionPro 8000 with four remote sensors, one in each unit and the temp is averaged.
    When its not windy we are all within one to two degree of each other. Replacement windows helped a lot.
  • "When its not windy we are all within one to two degree of each other. Replacement windows helped a lot."
    What is the temp difference when it is windy?
    Are the sensors in any of the cooler apartments, with no setbacks?--NBC
  • gfrbrookline
    gfrbrookline Member Posts: 683
    It is a corner building with half of the building facing east and the west side sharing a wall with the next building on the block, circa 1915 typical urban Boston block. The east gets clobbered during coastal storms and can experience a 5 or more temperature drop which is much better than it was before the new windows. It is a brick building so I have always assumed the east side cools down much faster during storms because they are getting the brunt of the wind/weather while the west side is insulated by the building next door.

    It is a six unit building, three on each side. We have sensors in all but the top floor units.
  • Jamie Hall
    Jamie Hall Member Posts: 17,060
    There really isn't much you can do about that wind cooling. If you can live with it... leave it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • gfrbrookline
    gfrbrookline Member Posts: 683
    Thanks for replying.

    I am trying to increase the efficiency of the system on normal days. So you would recommend adding Gordon D's to my risers to vent the air out?