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Aprilaire t-stat model 8535

carol_3carol_3 Member Posts: 397
Sorry for the delay--I've been on vacation. Normally you can't use a heat pump stat as a standard stat. It's because of the changeover valve function on a heat pump.

Comments

  • Ted_9Ted_9 Member Posts: 1,718
    Heat pump

    I have some of these t-stats and on the box they say they are for heat pumps, 1-heat, 1-cool.

    I want to use these as heating t-stat. Like to a taco sr or zvc control.

    My question for wiring is this. Can I apply 24 volts to r and c, then use the W1 for the heat call?

    Or connect a white and red from TT on the Taco box, then another wire to common on the transformer?



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  • carol_3carol_3 Member Posts: 397


    Another reason to change the stat is that the purpose of heating is comfort and the industry definition of comfort is +/- 1 degree from setpoint. That means the owner/user can't sense temp variation, which is highly desirable. Just two brands of thermostat can do that--both the "old standards"--White Rodgers and Honeywell. The others have much wider temp swing, which often means dis-comfort. And the temp swing gets bigger as the outside temp gets colder--not a time when you want to be messing around with user thermostat dissatisfaction--"it gets cold in here/then it gets hot in here . . ."
  • Ted_9Ted_9 Member Posts: 1,718


    OK, then can I use them as a "high limit" radiant t-stat? It would not call for heat, but i would wire them to shut down say one of 3 radiant actuators. I would do this so the radiant doesnt stop running, but one loop shuts down so the room wont over heat.

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  • carol_3carol_3 Member Posts: 397


    guess you could.
  • Ken D.Ken D. Member Posts: 836
    Heat pump stat.

    It really depends on the thermostat. Check the stat manufacturer's diagrams. Put a low voltage fuse in the R circuit in case of a mistake, so you don't damage the components. If you are using strictly for heating- with NO cooling- you can probably use it. As long as the stat would normally energize the reversing valve (O terminal)in cooling, hooking up the heat to the Y terminal would work. You probably will not have heat anticipation if using fossil fuels. A zone valve or electric heat would not matter. If you connect to the W or W1 terminal, it would still work, but the set point would be 2 degrees off the actual temperature as this method is usually 2nd stage heat. Using for heat/cool, would most times require a change over relay. If your'e going through all that, why not just get a new stat? Heating only electro- mechanical stats are dirt cheap. Some thermostats have a jumper between Y1 and W1 for heat pump duty. Removing the jumper will allow regular heat or cool with out changeover relay or temp lag, when connecting cool to Y1 and heat to W1. Again, this all really depends on the type of stat. Many stats would not work. Consult the stat wiring diagrams. If in doubt, get new stat.
  • Ted_9Ted_9 Member Posts: 1,718
    12

    I have 12 that I'd like to use and I dont install heat pumps.

    We mainly install hydronic heating. Whats a good application? Or do I just sell them on Ebay.

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  • carol_3carol_3 Member Posts: 397


    Ebay sounds good.
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