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  1. #1
    Join Date
    Jan 2007
    Posts
    10

    controls for freeze protection

    I have a system with three air handlers,one of which is in the attic.We are putting in a new boiler with tekmar control. Is there a way to set up a contol of to protect the unit in the attic against freezing. I know the loss of electricty is a liability, but we have a PV system to cover that end of the equation.

  2. #2
    Join Date
    Mar 2005
    Location
    Pacific Time Zone
    Posts
    4,228
    1. Put glycol in the system.

    2. Put a freeze stat in the supply duct, if you have supply duct that runs inside the building. If you only have ductwork in the attic then this won't work as you'll get nuisance trips.

    3. Put in a programmable controller with the logic that it will only shut down the fan if the outside air and mixed/supply air are both below 38 deg. F for 5-10 minutes and the indoor blower is proofed on. Here you would also want to turn the pump on if it cycles off and open the mixing valve/hot water valve to the ah heating coil so you have full flow. Then also have an alarm generated to someone that can take care of the problem in a relatively quick manner. Send it out via phone call, email, text message, and/or alarm with red light and a buzzer to where someone would likely be in the area to notify someone to handle it.
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  3. #3
    Join Date
    Apr 2007
    Location
    Sierra Foothills
    Posts
    20
    Which air handler manufacturer? I ask because most of them have a freeze stat as an option.

  4. #4
    Join Date
    Jan 2007
    Posts
    10
    The units are First Company units, two are 36vdx-3hw,one is a 24max-3hw. Older units that have been in use for about 17 years.

  5. #5
    Join Date
    Jan 2003
    Location
    USA
    Posts
    1,770
    Spring return actuators and a freezestat. Wire freezestat to kill power to the fan / econ dampers / heating valve. Freeze condition then closes OA damper, shutdown the fan and spring open the HW valve.

  6. #6
    Join Date
    Apr 2007
    Location
    Sierra Foothills
    Posts
    20
    For units, that old, you will have to contact them directly
    firstco.com

  7. #7
    Join Date
    Jun 2006
    Location
    Des Moines
    Posts
    287
    I agree with this. Just make sure the freezestat is correctly installed and that there isn't severe stratification in the unit, and you'll be good to go!

    Quote Originally Posted by orion242 View Post
    Spring return actuators and a freezestat. Wire freezestat to kill power to the fan / econ dampers / heating valve. Freeze condition then closes OA damper, shutdown the fan and spring open the HW valve.
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