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Help with purging air radiant heat system

Hi all,

I am looking for some guidance on how to purge air from my radiant heat system. I am new to this and basically have no experience doing this. I have attached the pictures with numbers of items I recall technician touched a year ago and hoping if someone can give me step by step relative to pictures what I can do to purge air out of system. Also the red handle is for the radiant heat loops to which there is 3 more that I recall technician was flushing

It is worthy to note, the system was working fine for as long as I remember. Then 3 days ago I heard water gurgling in system and today. I hear no gurgling but I also hear no water in any of radiant heating loops, any idea what could have happened? An air lock? I only hear noise in the red pump in pictures and holding the tubes the water flow feels weak.

Thanks for your help


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 6,736
    edited December 2022
    Not enough context to the pictures. The system that is connected to the pipes that are outside of the photo need to be part of the diagram

    For example here is a diagram of 4 different systems that have different ways to purge air from them. but they all have the same "out of context" design in the boiler room. (See the violet circled section of the system) Not knowing what your pipes are connected to makes it difficult to tell you what to do.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Ironman
    Ironman Member Posts: 7,223
    You need to determine the CAUSE of the air in the system, otherwise, you’ll soon be right back at the same place.

    Is the water heater your heat source? Does it have an internal coil for space heating or is it using domestic water?

    As Ed mentioned, better and more comprehensive pics are needed, including around the water heater.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • hot_rod
    hot_rod Member Posts: 20,790
    Looks like high pressure on the gauge, is this a combined hot water / radiant system?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream