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Islandaire hydronic PTAC fan won’t stay off

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KateRomanelli
KateRomanelli Member Posts: 3
in A-C, Heat Pumps & Refrigeration

Hi all - hoping someone familiar with Islandaire / hydronic PTAC units can sanity-check this.

I have an Islandaire EZRM Series unit (model EZRM16A2GAS15AA) with hydronic heat + aquastat. Even when the unit is switched OFF at the wall control, the fan turns on about every 15 minutes and blows air for a few minutes, then shuts off again.

I’ve tried all thermostat/display settings - the behavior is consistent regardless of mode. Feels like fan-only air. Every 15 minutes. Only in winter. Unit has been fully serviced 4 months ago.

My assumption is the aquastat is triggering the fan when hot water cycles through the building, overriding the OFF setting.

There’s also an N.O./N.C. switch on the side, which I haven’t touched. N.O. is on.

Questions:

  • Is there any way to disable or limit the fan cycling (purge / aquastat override / ventilation)?
  • Or is cutting power at the breaker the only way? Would this damage the unit? Or can I just turn it back on in summer when I need AC?

Thanks for any insight,

Kate

old_diy_guy

Comments

  • pecmsg
    pecmsg Member Posts: 6,878

    it’s circulating to sense temperature

  • KateRomanelli
    KateRomanelli Member Posts: 3
    https://forum.heatinghelp.com/discussion/comment/1884137#Comment_1884137

    thank you. do you know if it can be turned off? it's blowing unnecessary air into our living room and gets really loud for a few minutes. Especially since our other, older units don't seem to be needing to do this. thanks so much

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,881

    I am sure this problem can be solved. But to provide any relevant input we would need to see the wiring diagram. I went on the Island Aire web site but could not find this information.

    Maybe you can post a screenshot of this or have the install manual. If not maybe you can locate one from Island Aire.

    It shouldn't be too hard to figure out the issue.

    As far as shutting the fan off and turning it on for AC do't you run this unit for heat?

    KateRomanelli
  • pecmsg
    pecmsg Member Posts: 6,878

    Most PTAC units shut the heat pump off below 40°F and run straight electric.

  • HVACNUT
    HVACNUT Member Posts: 7,305

    @KateRomanelli , can you try tapping the aquastat to see if it stops the fan? They get hung up sometimes.

    Can you see what temperature the aquastat is set to, and is there a differential? You might need to take the cover off.

    KateRomanelli
  • KateRomanelli
    KateRomanelli Member Posts: 3

    Thank you all! If i take the cover off it looks like this: Included in the four pictures is also the wiring diagram. I am not sure how to find the aquastat, does it look like a thermostat? Thank you!!

    https://imgur.com/a/a101UmT
  • mattmia2
    mattmia2 Member Posts: 15,984
    edited January 26

    This is the um…"aquastat". It is just a fixed snap disc thermostat that presumably turns on the blower when the outlet of the steam coil is hot. It might work better on the inlet.

    image.png
  • pecmsg
    pecmsg Member Posts: 6,878

    outlet is perfectly

  • HVACNUT
    HVACNUT Member Posts: 7,305

    Take the disk limit off the pipe and see if it stops.

    All the switch settings are correct?

    mattmia2
  • mattmia2
    mattmia2 Member Posts: 15,984
    https://forum.heatinghelp.com/discussion/comment/1884317#Comment_1884317

    seems like the outlet would only work if the steam makes it to the trap. if as soon as the blower comes on it starts condensing all the steam that is entering the return will cool an depending on the setpoint of the snap disc thermostat it may turn off then the return fills with steam again, turns the thermostat on and the cycle repeats.

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