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Powering OPS-300?

amxhobbyistamxhobbyist Posts: 90
in AMX Hardware
Does anyone know if I can power an OPS-300 thermostat off something other than 24 volts AC?

I have an RV with four heating zones (4 thermostats running 4 separate heaters) currently using some old mechanical thermostats. I want to switch to digital, communicating 'stats so I can sync all zones from a single touchpanel and quit running around to manually adjust 4 different thermostats.

I have several OPS-300 thermostats laying around. I need to be able to power them on 12vdc. I've had zero luck finding inexpensive, small 12vdc to 24vac inverters. Does anyone know if I can run one of these thermostats directly at 12vdc, or even 24vdc (dc, not ac)? What are the electronics actually using for power - do they step it down internally?

I know it's a long shot to get an answer to this question, as I doubt anyone has actually used these for something other than what they were intended, but thought I'd try, anyway. :)

Comments

  • viningvining Posts: 4,368
    Have you looked for a standard 12vdc - 120 ac inverter and just buying a standard 24 v 40va transformer?
  • amxhobbyistamxhobbyist Posts: 90
    I have, but that's going to be very inefficient. I have inverted power on board, just don't want to rely on it to run the heat if I can help it.

    I'm of the understanding that some thermostats just take the 24vac and convert it to dc on board and that you can often just feed them 24vdc and they work fine. Would be great if the OPS-300 was like this, I can go 12vdc to 24vdc easy, it's the 24vac conversion that's the issue. Maybe someone around here knows whether a 24vdc feed will work. I could just try it, but would rather not fry a thermostat.
  • DHawthorneDHawthorne Posts: 4,584
    Somewhere along the line, they must be converting it to DC. There was a day you could tell where the rectifier circuit was and how it was wired, but in these days of SMD's, I couldn't tell you from looking at one if feeding it DC would be harmless or not. But, chances are it is. They almost always run it directly to a rectifier, and generally they don't care if it's AC or DC. Just give Aprilaire a call and ask them. Worst that can happen is they will say, "I don't know, but I don't recommend it ..." and you won't be any worse off than you are now :).
  • Joe HebertJoe Hebert Posts: 2,159
    amxhobbyist wrote:
    I have an RV with four heating zones (4 thermostats running 4 separate heaters) currently using some old mechanical thermostats. I want to switch to digital, communicating 'stats so I can sync all zones from a single touchpanel and quit running around to manually adjust 4 different thermostats.
    You have an AMX system in your RV? Cool. :)
  • alexanboalexanbo Posts: 282
    More impressive then an AMX system in the RV is needing 4 thermostats to control the HVAC system of the RV....
  • John GonzalesJohn Gonzales Posts: 609
    alexanbo wrote:
    More impressive then an AMX system in the RV is needing 4 thermostats to control the HVAC system of the RV....

    My thoughts exactly! A four zone HVAC system in an RV?! Cool!

    --John
  • alexanboalexanbo Posts: 282
    John Gonzales wrote:
    My thoughts exactly! A four zone HVAC system in an RV?! Cool!

    --John


    .. Or warm depending on the weather outside
  • John GonzalesJohn Gonzales Posts: 609
    :)


  • amxhobbyistamxhobbyist Posts: 90
    LOL... Yes, I have a 40 foot coach with 4 HVAC zones, believe it or not. No AMX system in it yet, but I'm installing one. I'm going to start with HVAC control. I actually have 4 air conditioners and over a dozen heaters (each zone has separate electric, propane & engine heaters, except the bathroom which only has 2 heaters, so 14 heaters total throughout) and I'd like to control 'em all from the driver's seat. So I figure I'll replace my backup camera monitor with a touchpanel and overlay "pop-up" controls on top of the image.

    Eventually I'll add a couple more panels and integrate tank fluid level sensor displays, maybe lighting control, etc... But for now, I just want my heaters to be on communicating thermostats. I'll use one OPS-300 per zone (if I can run 'em off 24vdc) and use relays to determine which heater is switched on, depending on available resources (electric if 50 amp service is available, engine if engine is running, propane if neither).

    So, I guess now I hook an OPS-300 up to 24vdc and hope I don't let out the magic smoke. :)
  • joelwjoelw Posts: 175
    The OPS-300 is an Enerzone/Aprilaire 8840.
    The newer VST is an Aprilaire 8870.

    If the site allows this is the install manual for older communicating stats:
    http://www.aprilairecontractor.com/pdfs/DP10004345.pdf

    Depending on the rectification circuit your DC level will want to be higher 32/36 volts.
    The best method short of contacting the manufacturer is measure the circuit post the main DC filter cap. I would look at using a adjustable DC/DC converter to run the stats.

    If you don't get anywhere with Aprilaire let me know, I have a few of the 884x stats in inventory I can do some measurements on.

    The key is the DC/DC converter.

    I've done quite a bit of engineering/programming for high end motor coaches and movie trailers over the years. Bruce Coach and Country Coach to name a few.

    The 8870 or the 8570 stats would be recommended over the 884x series, especially on a new install.
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