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Hydrocoil system blowing cold air

heynowjerryheynowjerry Member Posts: 3
We have a few hydrocoil systems in the house, and 1 of them stopped working all of the sudden. The air is blowing cold. Thermostat works, fan kicks on as required, but the air is cold.

Could this be hot water not making it to the unit? Something else I can check?

Thanks in advance.


  • Fan Coil

    In order for the fan coil to get hot water from the boiler, there should be a zone valve opening or a pump starting to spin in addition to the boiler coming on. If the zone valve or pump are getting power and not opening or turning on, you may need to replace one of them. If the zone valve and pump are operating correctly, it could be the boiler that's not turning on. The boiler will get a signal to turn on from a relay in the zone valve, pump controller or directly from the thermostat.
    Often wrong, never in doubt.
  • heatpro02920heatpro02920 Member Posts: 991
    Like Alan said

    the air handler needs a zone valve and or a circulator to gets its heat from the boiler... Let us know which you have and maybe a picture of the boiler and its near piping, and we can be more help...

    This time of year I find frozen attic handlers and another issue to keep in mind is an air bound unit or pump, but it can very well be a faulty pump, control, wire, or zone valve...

    Note- if you do have zone valves, then you can manual open the valve that feeds that unit, it should circulate hot water as long as another zone is calling simultaneously. If this is an attic exchanger with no freeze protection additives and your climate is that where the unit is in danger of freezing, I would either drain it down or ensure it is circulating before you run into more trouble..
  • heynowjerryheynowjerry Member Posts: 3
    edited March 2014
    Good advice

    Appreciate the zone valve help.

    I located the valve. It clicks continuously when i turn on the thermostat. I assume it's dead. (Picture attached)

    Easy to replace? No soldering, right?

    Can i just replace the motor?

    Edit: noticed the water inlet is cold, so definitely no hot water getting to the unit. Need to locate the zone valve. Up in the attic with the Hydorcoil unit, or downstairs with all the radiant zone valves??

    For additional data, Boilers (working fine) sending water to an 80 gallon insulated large blue water container, which i imagine disperses the hot water to the radiant system and to each zone when called upon.

    So if i'm reading this correct, my particular problem HydroCoil system's specifc zone valve could be bad, or another unit specific control, as Radiant and other Hydro's are fine.

    Thanks in advance. Ill try and grab a pic, if i can locate the zone valve. I imagine it's close to the unit?
  • heatpro02920heatpro02920 Member Posts: 991
    That eerie zone valve

    will have an manual open lever, push it to manual open and have one of your other zones call at the same time, if your ah starts blowing hot air that is your issue, not sure why you would have another zone valve at the air handler itself?
  • Erie

    That zone valve is a "Pop-Top" model; easy to replace the operator (motor), part number AG13A02A, 24 v., 2 position, normally closed.
    Often wrong, never in doubt.
  • heynowjerryheynowjerry Member Posts: 3
    edited March 2014
    Right part

    Thanks much.

    And you think that 'clicking noise im hearing' indicates that it's only that part, and I dont have to replace the whole valve?

    And no soldering, just pop it in?

    Appreciate it.
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