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Tamper proof tstat

I'm looking for a tamper proof tstat that fits the following criteria: Inexpensive (read that less than $150, but $50 would be nice), non electronic or possibly battery operated. This would be for an apartment building. The current tstats only control a Taco ZV which is in their space. If I went with remote sensor I'd have to run new wires down to the basement. If I go with a lockout screen type like the MH 8000 series, the tenants will probably destroy it. I've never seen a lock box that really keeps people out.The landlord is looking for an inexpensive way to keep the tenants from cranking the stats.

Accustat used to make a stat with a snap in mercury bulb that was pre-set for a temp, but no more mercury.


  • Brad White
    Brad White Member Posts: 2,393
    Good, Fast or Cheap. Pick any Two.

    Well, maybe "fast" does not enter into this equation... I think lock boxes are your safest bet if they are the welded wire cage types (JCI has these among others). But as you note, the presence of a cage screams, "Challenge!" and ingenuity on the part of the vandal takes over.

    Short of a 480V or a 13,800 V line voltage thermostat, I cannot think of a conventional application to suit you. ;)

    That said, a discrete sensor with remote setpoint adjustment might be your best bet. A Ranco type controller (if all you need is an on/off output) or a thermistor sensor with proportional output might be your best bet. Tekmar, Honeywell Centra (if they are still in business), Danfoss and others come to mind.

    The actual adjustment can be under lock and key in the building management office and the space might see an embedded button, painted over or in a discrete location. A remote sensor can also monitor the space temperature without subjectivity.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,557

    Thanks for the input Brad.

    This location has 40 buildings. Each building has 4 apartments and one residential boiler feeding them. Currently no outdoor reset. When it gets cold enough outside, the boiler fires to high limit and the circulator runs. When a tenant needs heat, the tstat opens the ZV to let the hot water through. Primitive to say the least.

    I think there would be a lot of labor time to go the remote sensor route which is why I was looking for something stand alone. I may look into something a little more industrial like a Ranco type. These places aren't nice. Even a Ranco may be a step up.
  • Glenn Harrison_2
    Glenn Harrison_2 Member Posts: 845

    Accustat is showing on their website that the mercury stats/sensors are still available, as well as their new E-Accustat electronic version.
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,557

    I saw the mercury stats on their site, but haven't called. Can't imagine they're still available. The electronic need power. That would mean running more wires.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    Here are some possibilities, but I don't believe there's really such a thing as a tamper-proof thermostat--at best you get tamper-resistance but they can get awfully expensive...

    White Rogers 1F85-275 Looks like just a 3-digit code is required to unlock, so not too difficult to crack by a determined person...

    Temp Proof Temperature Limiting Thermostat Presuming this is for heat only, I suspect the cost will be quite reasonable with such a large quantity.
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,557

    THanks, Mike. I'll do a little more research on those.
  • carol_3
    carol_3 Member Posts: 397

    How about the old fashioned T822 with a limited range? There's the T822D1255 with a temp range of 35 to 65 (too cold?) and the T822D1719 with a range of 38-72
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,557

    But aren't those mercury bulb stats? Are they still available?

    The other problem would be that these stats have to operate Taco ZVs. Do the Honeywell heat anticipators go up high enough for those valves?
  • John Cockerill
    John Cockerill Member Posts: 94
    remote t stat

    To use the same therm wores unshielded you can go with a battery operated Danfoss 7000 remote t stat
  • carol_3
    carol_3 Member Posts: 397

    The 1255 goes up to 1.2A. The 1719 goes up to 1.0A. I don't know what the Taco is, but it seems this oughta do it. I don't think Honeywell sells any mercury bulb stats anymore.
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,557

    The Taco head draws 0.9 amps so that would be fine. The T822d stat is mercury and is obsolete per Honeywell. The replacement stats are T822k or T827K, both have a max of 90 degrees. I looked at White Rogers and it's the same thing.

    Why does anyone make a heating only tstat that goes to 90 degrees. Is there another common use that I don't know about. Shouldn't they all be limited to a max of 75, and even that is too high. We keep our house at 62 in the winter which I realize is cooler than most.

    At a previous company we had a 100 unit apartment building for a customer. The apartments were so hot in the winter you couldn't be in there for more than a few minutes. Many of the tenants were originally from the islands and they liked it hot all year. Since the utilities were built into the rent they would just bury the stat at max and walk around in t-shirts and shorts through the winter. Is it any wonder we use so much energy.
  • carol_3
    carol_3 Member Posts: 397

    Sorry about misleading you. I too am perplexed about the 90 degree max. Can't think of any application for that. Well, let's see what responses you get on your Wall posting.
This discussion has been closed.