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1 pipe steam temperature control valves

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tkos115
tkos115 Member Posts: 94
So with the heating season on the horizon here in the northeast, I was wondering if they make a temperature control valve for a 1 pipe steam system. What I'm talking about is, control valve that takes the place of the normal twist valve at each radiator. I heard someone talking about "thermostatic" valves that you can set to a desired temperature that will only allow steam to flow into the radiator if the room is cooler than what it's set at. Is this a product that is offered for a one pipe steam system, and if so are they a decent item to install at each radiator?


Thanks for your time and help all!

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  • Jamie Hall
    Jamie Hall Member Posts: 23,323
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    Yes. They are called thermostatic controlled vents. Like this:
    https://www.supplyhouse.com/Honeywell-V2042HSL10-1-8-One-pipe-Steam-Radiator-valve?utm_source=bingad&utm_medium=shopping&msclkid=baa927fe85a3191725a478b970621afc
    the valve screws into the vent opening, and the vent screws into the other opening.

    Whey will work to turn off the heat if the room is too warm. They will not turn on the heat if it's too cold.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    STEVEusaPA
  • ethicalpaul
    ethicalpaul Member Posts: 5,704
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    > What I'm talking about is, control valve that takes the place of the normal twist valve at each radiator.

    Just to be clear, the valve on your 1 pipe radiator is not a control valve to modulate how much heat is produced. It can be used (if it's not failed) to completely shut off the radiator from steam, but it only has two valid modes: fully open, and fully closed
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    STEVEusaPA
  • tkos115
    tkos115 Member Posts: 94
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    Thanks! My other question I forgot to mention is, can this be placed on the radiator thats located in the same room as the boiler thermostat? My guess is no because it would cause the boiler to turn on but not necessarily heat the room if the radiator isn't receiving steam.
  • tkos115
    tkos115 Member Posts: 94
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    > What I'm talking about is, control valve that takes the place of the normal twist valve at each radiator.

    Just to be clear, the valve on your 1 pipe radiator is not a control valve to modulate how much heat is produced. It can be used (if it's not failed) to completely shut off the radiator from steam, but it only has two valid modes: fully open, and fully closed

    Yeah sorry I didn't word that correctly, but yes thats what I'm talking about. Those are either all the way on or off.
    ethicalpaul
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,846
    edited August 2020
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    To better understand the way a thermostatic radiator valve (TRV) operates on a one-pipe steam system, you need to understand how steam and air work in a steam system. Steam and air don't mix. Like oil and water don't mix. If there is air in the radiator the steam can not get in. So if you want to keep a room from overheating, shut off the vent opening to the radiator in that room. The air can't get out of the radiator, so no steam can get into the radiator. No steam ... no heat!

    If you put the standard TRV on the supply opening of the radiator, the valve may close with some steam in the radiator. Once the steam cools and condenses, the water will be trapped inside the radiator until the next time the room needs heat. When the TRV opens the water will find its way back into the steam main. If the steam main is charged with steam at that time... then the water may flash into steam causing a very loud banging in the pipes.

    These tiny steam explosions can be very violent at times. To put into context. Dynamite will increase in size by a factor of 900 to 1000 times its original size when exploded. Water will increase by 1700 times its original volume when converted to steam. That is why steam systems that are poorly designed or have pipes that have settled over time, will sound like someone is banging the boiler with a very large sledgehammer when the condensed (water) hits a hot steam pipe trying to find its way back to the boiler.

    I hope this helps @tkos115
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
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    If you are having problems with unequal heating in some rooms, it may be due to bad main venting, and/or over pressure.
    Check your main vents, and your pressure gauge, , and post a picture here.—NBC
  • retiredguy
    retiredguy Member Posts: 906
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    The thermostatic valves that everyone commented on will work very well on most applications. When I used these valves I would install the thermostat in the coldest room with no control valve on the rads in that room unless there was a separate boiler cycling device that was long ago called a "weatherman". To get these devices to work properly the boiler has to cycle on and off
  • tkos115
    tkos115 Member Posts: 94
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    I've heard of potential water hammer with these but i'm hoping it won't cause any issues. I don't have any unbalance in the heating on this system. Last year I went through it and got it "tuned" pretty good. It's been a very quiet system except for one of the header pipes that runs upstairs. While the pipe is heating up it makes a popping noise because where it runs through the first floor it's tight. I have to try and cut the hole it goes though a tiny bit bigger.

    My main reason for wanting to use these is to try and gain some more efficiency this heating season.
  • dopey27177
    dopey27177 Member Posts: 887
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    If you use a control valve (not recommended) you must use a normal open control valve,

    The reason for this is when the valve closes to stop steam from entering the radiator some water is retained. When the valve opens to supply heat that small amount of water will drain and steam will enter the radiator for that heating cycle until the vent valve close and steam stops. The control valve remains open and will allow the condensate to drain until the heating cycle is over.

    Typically, if the thermostat is in the proper location the radaitor is sized a bit smaller than the rest of the radiators. If you use a trv or control valve you may lose control of the heating in the rest of the house.

    The installation of temperature controls on radiators is not recommended unless you want to keep much lower temperatures in rooms not used or in some cases lower temperatures in a bedroom where sleep can be disrupted if the room gets to hot.

    My recommendation is to use a Danfoss trv at the vent valve. Make sure the trv comes with a built in check valve. The check valve is needed to prevent a vacuum from forming in the radiator.

    Remember one pope steam systems breathe, air out ti make heat, air in to allow condensate to return to the boiler.

    Jake
  • jumper
    jumper Member Posts: 2,259
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    Blankets on radiators are pretty fool proof. If rads are two pipe and you're quite handy then study the jj wilson fitting on this site. An issue to consider is that air may be driven down into supply instead of out radiator's vent.
    ethicalpaul
  • gennady
    gennady Member Posts: 839
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    The room with thermostat can’t have trv installed. Just air vent.
  • ChrisJ
    ChrisJ Member Posts: 15,704
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    Something that needs to be mentioned and it may have been, is that TRVs work well and they can even slow down venting allowing a radiator to heat less than normal. It's not a simple on/off device.

    However, the vent you use with it must be close to correct otherwise it will still over heat or, heat too little no matter what.

    A TRV on single pipe steam will also not stop a radiator from heating if it closes during a cycle. Meaning if the boiler is firing and the radiator is getting steam it will continue to do so until the boiler shuts down.

    It's been my experience more cycles is better with TRVs. With a Honeywell thermostat I would recommend trying 2 or 3 CPH and let it run for a day or two to settle down.

    I have TRVs on 5 out of 10 radiators in my house, including both in my kitchen so they do not heat when the oven is on, or, if the sun has warmed the room as it's on the south side of the house.

    Both Danfoss and Macon make good TRVs for single pipe steam and I have both in my house but I prefer the Macon's.

    https://www.supplyhouse.com/Macon-Controls-MAC-OPSK-W-EVO-1-8-Threaded-One-Pipe-Steam-Straight-Valve-Assembly-with-EVO-28-Operator
    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
    ethicalpaul
  • Gordo
    Gordo Member Posts: 857
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    My 2 cents on single pipe steam radiator TRVs. Hope it helps!
    https://www.youtube.com/watch?v=hjS5slMqtuA
    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.
    https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
    ethicalpaul
  • dopey27177
    dopey27177 Member Posts: 887
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    Outstanding educational demenstration of how TRV's work.

    Jake
    Gordo