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Hydronic system blowing cold air

a_tebo48 Member Posts: 1
I have a oil fired boiler with and air handler with a hot water coil. The boiler comes on and comes up to temp and shuts off. Both zones circulators are working and water is circulating. I have hot water going into the coil and coming out of the coil but it's still blowing cool air out of the vents.


  • Jamie Hall
    Jamie Hall Member Posts: 22,924
    Three possibilities. Too low a water temperature going in. Too much air flow. Not enough water flow.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Ironman
    Ironman Member Posts: 7,350
    There could be an internal 3 way valve in the AHU. It could simply be bypassing the coil and sending hot water back out.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.