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Difference between main vents and radiator vents?

Im new to steam and as i wrap my head around how things work im wondering about radiator vents . What makes them close ,is it temperature ? If so what is that TEMP ? Main vents, are they similar inside and if so ,when and how do they close ? thanks


  • Snowmelt
    Snowmelt Member Posts: 1,415
    The steám pushes the air out and closes on temp. The vents have different size holes to let the air out.
    The main gets the air out quicker then the rad vents take care of itself. That's the simple way, keep in mind your steám is traveling slow, so venting correctly makes the boiler work in your favor of energy efficiency
  • Fred
    Fred Member Posts: 8,542
    Radiator and Main vents are basically the same internal construction. They close on heat, typically somewhere around 140 to 150 degrees. There are two popular types, float and bi-metal. The float type has a float in it that is filled with alcohol or other fluids that expands when heated and causes the float to push a needle type device up into the airway and close the vent. The bi-metal types, have a metal strip in them that expands when heated and that spring action pushes the needle into the airway, closing the vent. In both cases, as they cool, the float drops and the bi-metal strip contracts, opening the airway.
    Hoffman vents use the float technology while Gorton uses the Bi-metal approach. Both are very reliable.
  • misterheat
    misterheat Member Posts: 158
    I have a 1 inch tapping that is currently capped. There is only 1 radiator behind it . Would putting a vent in the tapping help or hurt the last radiator in the run ? I DO NOT have a short cycling problem. Just looking for ways to get the air out even quicker and the steam moving . thanks