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I have to manually power cycle air handler to get zone to provide heat

dhoskyns
dhoskyns Member Posts: 3
in Thermostats and Controls
2-zone AC/hydronic heat system:

2- Zone system AC / Hydronic heat

Buderus boiler

Taco SR-502 relay

ADP Air handlers

Zone 2- works perfectly

Zone 1 - A/C works and manual fan control works. But when I call for heat on my thermostat nothing happens - No red zone 1 light on Taco relay, circ pump doesn't run and air handler doesn't blow. HOWEVER if I flip the power switch on the side of the air handler off/on and wait 5 seconds, the red zone 1 light comes on on the Taco, circ pump and air handler turn on and I get heat. This works every time...Issue happens 2-3 times a day.....does anyone have any idea what the issue is? I have already replaced the thermostat. Is the the Taco relay bad or possibly the 24v relay inside the Taco? Any thoughts appreciated.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,856
    Much more likely to be a problem with a switch in the air handler than something with the Taco. Figure out how the air handler tells the Taco to turn on, and trouble shoot from there.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    dhoskyns
  • dhoskyns
    dhoskyns Member Posts: 3
    Thanks Jamie. I will start with the air handler. Not too much inside to troubleshoot..


  • HVACNUT
    HVACNUT Member Posts: 6,332
    Do the Red and White wires herego to the Taco relay? If so it's probably faulty contacts in the sequencer. Get the numbers off it and order a new one.
    dhoskyns
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,477
    Can you turn the fan to constant "on" at the thermostat will the thermostat start the heat? This could get you going until you can troubleshoot. It could very well be the sequencer as @HVACNUT mentioned.
    dhoskyns
  • dhoskyns
    dhoskyns Member Posts: 3
    Yes, the red and white wires go to the Taco.....ordering a new sequencer.
    Thanks @HVACNUT and @EBEBRATT-Ed

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