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Single-pipe woes

FizzFizz Posts: 468Member
Recently insulated back-side of parallel flow system, changed main vening, switiching-out MOM 1's on each main to Gorton#2 on back-side, and 2 Gorton#1's on front. Result, faster steam getting to end of main, but increased pressure and heat swings. Realizing we're in the middle of cold snap, single digits at nite, system seemed more manageable with no insulation and less venting. Thinking a 3cph t-stat might be appropriate. Currently have t-822d, and no matter where anticipator is set no improvement. Current setting is at lowest setting, which is higher than control unit Genysis 7505 amp rating of .1

Comments

  • FredFred Posts: 7,727Member
    edited March 6
    - Have you rebalanced the radiators since you insulated and put the new vents on?
    - - How over sized is the boiler? If it is considerably over sized, the insulation has caused less steam condensation getting to the radiators and that may contribute to the increase in pressure.
    - Do you have the Pressuretrol set at .5 Cut-in and 1PSI differential?
    - Are you sure the pigtail is clean?

    I would set the anticipator back to where it was before you started adjusting it and rebalance the radiators and check the other items on the list above. It is also possible that you are going the wrong direction with the anticipator.
  • JUGHNEJUGHNE Posts: 5,439Member
    I had this happen on a larger single pipe system.
    2 mains totaling 220' of 3" pipe.
    Used to run 3-7 oz. cycled by t-stat only.
    After insulation would run up to more than 1 PSI, leaks showed up at valves etc.
    Added vapor stat and more G2 main vents on each main, total of 5 on each.
    After that it would seldom cycle on pressure.
    EDR was a close match.
  • FizzFizz Posts: 468Member
    Fred, haven't re-balanced since other side insulated, boiler is SGO-3, 354sf EDR, attached rad is 220; yes to p-trol question. As for anticipator, shouldn't it match or close as possible to boiler control amps?
  • FizzFizz Posts: 468Member
    EDR is 220, boiler 354, mains are 2" of about 25 ea side, and 11/2" of 30' ea side.
  • FredFred Posts: 7,727Member
    edited March 6
    Fizz said:

    Fred, haven't re-balanced since other side insulated, boiler is SGO-3, 354sf EDR, attached rad is 220; yes to p-trol question. As for anticipator, shouldn't it match or close as possible to boiler control amps?

    Sounds like the main venting is ok. As for the anticipator, that's typically the instructions provided for forced air. I'm not sure that always holds true though, especially for steam:

    "Many non-programmable mercury switch thermostats have a heat anticipator switch to help operate the furnace. The heat anticipator cuts off the furnace, but not the blower, in "anticipation" of the heat left in the furnace that has not come through the vents. This allows the furnace to operate efficiently. When the furnace is cutting on and off too often or the room is not reaching a desired temperature, it is necessary to adjust the anticipator. "
  • FizzFizz Posts: 468Member
    I'm wondering if the fact that the boiler is oversized has anything to do with issue?
  • ChrisJChrisJ Posts: 9,506Member
    edited March 9
    If your boiler is oversized and you insulated the mains you want as much main venting as you can do and short thermostat swings.

    2-3 CPH might work well, or on a mechanical thermostat a shortened anticipator setting, I.E. lower number.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • FizzFizz Posts: 468Member
    Thanks Chris!
  • FizzFizz Posts: 468Member
    Yesterday I re-vented mains, moving G2 and MOM-1 to front, and 2 MOM-1's to back, resulting in back getting steam to vents quicker! Timed steam from cold start, with steam full at header, took steam 10' to get to back vent, and 15' to front. It seems the less I vent the quicker getting to main vent. Rads start heating soom after steam gets to their feed. Another anomoly is steam starts down drop to boiler drip before heading to vents. Vents are on antlers. This anomoly has been present from moving in to house back in 3/18. Strongly considering a MOM-1 or G1 on each main and going to mechanical t-stat with lower anticipator setting, either White-Rodgers 1E3ON-910 with settings from .15-1.2 or Robershaw 986-1 with settings of .1-1.2. Current t-stat is mercury T822D, with .18 as low setting. Current control unit Genysis 7505 amp rating of .1. Any thoughts? Jamie, I know this violates the bible of mercury t-stats.
  • nicholas bonham-carternicholas bonham-carter Posts: 7,763Member
    Time the steam from a hot start, and see how long it takes. The Gorton 1 is good for only a 10 foot length of main, so you may need some Big Mouth vents on each one, which will do for 50 feet of 2 inch pipe.--NBC
  • FizzFizz Posts: 468Member
    The side with 2 MOM1's vented 4' quicker than with the G2 and Mom1; and when reversed, the slower side with smaller vents got to vent about 10 sec sooner.
  • FizzFizz Posts: 468Member
    I was thinking of plugging main vents which have approximately 50' of wasted steam, and letting rads vent supply main, and keep return mains closed thereby not having to vent needlessly. When I had a G1 on each side the steam never got to vents but rads heated quicker.
  • FredFred Posts: 7,727Member
    You don't want to let small radiator vents try to do the job of main vents. You are not wasting steam by heating the main pipe that has no radiator run outs on it. That's the way your system is designed and, like it or not it will use some steam to heat that main. You can minimize that by putting your main vents as close to the last radiator run-out as possible but it isn't a priority. The question/issue that needs to be resolved is why does your main heat faster without main vents than with them or with smaller main venting than with larger ones. The answer may be that you have such large vents on your radiators that the steam starts down the radiator run-outs before it fills the mains. That leads to uneven heating in the living spaces and you will never get all the spaces balanced.
  • FizzFizz Posts: 468Member
    Here is venting for rads: back side-wall type 9sf gorton5, collumn 30sf MOM5, coll 24sf G5, iron tube21sf MOM4; front col42sf MOM5, col33sf GD, It 21sf Heat timer 1/2 setting and col38sf MOM6. I used table from Gerry Gill and Steve Pejak as guide.
  • FredFred Posts: 7,727Member
    That Heat Timer alone at 50% vents faster than a Gorton #1 Main vent. You are making the steam flow far easier to go to those radiators than to get to the end of the Mains. When the larger radiator vents close from steam, then the steam flows to the end of the main (next easiest path).
  • FizzFizz Posts: 468Member
    Actuallly I have it at about 1/4, it's 2nd floor and the last run on front main and last to heat.
  • FredFred Posts: 7,727Member
    Fizz said:

    Actuallly I have it at about 1/4, it's 2nd floor and the last run on front main and last to heat.

    I stand by my original comment. Based on the way you have the radiators vented, the steam will not fill the mains before it starts to flow out to the radiators. No way to balance the system. The Heat timer is too fast, a Gorton D vents at the same rate as a Gorton #1 Main vent, A gorton C is not much slower that a Gorton #1, Steam can easily go all directions and eventually end up at the end of the main, if the boiler runs long enough.

  • gfrbrooklinegfrbrookline Posts: 359Member
    There are very few steam systems that benefits from heat timer vents. They were a good concept but they vent way to fast and only add to balancing problems. Try a Vent-Rite #1 that can be easily adjusted and see how you make out.
  • FizzFizz Posts: 468Member
    Thanks guys! Here are numbers I got for each radiator's cubic feet of air using Gerry Gill's chart for balancing a steam system:
    Front side- 1.05; .825; .525; .94 =3.339
    Back side: .252; .75; .60; .525=2.13
    What would be proper size rad vents?
  • FredFred Posts: 7,727Member
    Fizz said:

    Thanks guys! Here are numbers I got for each radiator's cubic feet of air using Gerry Gill's chart for balancing a steam system:
    Front side- 1.05; .825; .525; .94 =3.339
    Back side: .252; .75; .60; .525=2.13
    What would be proper size rad vents?

    Try the Vent-Rite #1 that @gfrbrookline suggested. They are very reliable and can be adjusted to address the spectrum of needs from "off (or near off)" to 0.083 CFM at 1 ounce of pressure (in eight incremental steps). A far more appropriate venting range for radiators.
  • FizzFizz Posts: 468Member
    Ok, thanks Fred!
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