How does my office thermostat work?
November 6, 2014 2:14 PM   Subscribe

Is there any guide for best practices on setting a 2-dial thermostat like the one pictured here and here? And what do the two dials represent?

I won't embarrass myself with the various things I've been told the two dials are for.

Whenever I or an officemate tweak our thermostat, nothing good or predictable seems to come of it. Maybe nothing happens, or sometimes odd condensation effects on our windows.

I'm quite sure it's active and connected, not just a vestigal box on the wall.

posted by spbmp to Technology (10 answers total)
It looks a little like a T-4000 series thermostat. There are dual dial ones in that line that use one for day and the other for night, but there are also some that use one dial for heating and the other for cooling. (I guess maybe in that second case the whole HVAC system switches depending on the season?)

If you can find the model number, you can probably find a product page for it that says what it does, and possibly even a manual.
posted by aubilenon at 2:26 PM on November 6, 2014 [1 favorite]

I have heard (from a company that designs heating/cooling systems) that it's pretty common for companies to deactivate controls, so they don't actually work (and just come on automatically) that is a possibility. Can you check with an office manager or building manager?
posted by three_red_balloons at 2:31 PM on November 6, 2014 [1 favorite]

Yes, I've heard the same thing: if you can access the controls (as opposed to it being under lock and key) they're just there to make you feel like you have control over the temperature. See also, "push to walk" buttons that are really on timers. Exceptions exist of course, but your own experience seems to point to this.
posted by Room 641-A at 2:41 PM on November 6, 2014

Thermostats in large offices are often just for show, but there's still a good chance your thermostat is connected, especially if the overall classiness of the environment is kind of low.

I'd start by reassuring myself that the box actually does something. Turn both dials all the way to the left and wait for one hour. Did anything happen? Then turn both dials all the way to the other right and wait for one hour. Did anything happen? When evaluating if anything changed, be sure to walk around the building just a bit. You're looking for ways in which your office is now a different temperature from the nearby hall, but also checking to see if somehow the thermostat controls your whole section and 3 neighboring offices. Confirm that there are vents in your space, and that they're outputs not inputs.

Also, just email the building facilities supervisor: It's really cold in my office. Can you fix that for me, or am I supposed to use the old dial thing on the wall?
posted by aimedwander at 3:11 PM on November 6, 2014

Response by poster: Let's assume it's working, because I'm sure they're working! (Tried to address that in the question, but I'm glad you included the links for others.) How can I find the model number and manuals?

Ah, the T-4000 guess led me to this info sheet, which looks like a match! (There's also some other irrelevant T-4000 thermostat in google-land that's digital.)

I guess perhaps it's a heating-cooling thermostat like the T-4600 listed there, since that one has "set points for heating and cooling"

Not sure what these model-types refer to: "Available in dual direct, dual reverse, or direct and reverse action models, the independent set points can result in a deadband to encourage energy conservation and prevent energy waste by eliminating heating and cooling overlap"

Does this all mean simply that one dial is irrelevant? Is there something else the two dials might mean? And is the top dial for heating (based on my unimpeachable logic that you "heat up")?
posted by spbmp at 4:33 PM on November 6, 2014

Response by poster: Uh oh, there are also dual-temperature day/night models listed in the table there, like the T-4506.
posted by spbmp at 4:35 PM on November 6, 2014

Uh oh, there are also dual-temperature day/night models listed in the table there, like the T-4506.

Right, it looks like it varies from model to model. I couldn't tell whether it also depends on how the rest of the system is configured, or if you have to get the model that matches your configuration.

As far as I can tell, the "direct" and "reverse" stuff is about how the thermostat interfaces with the system, but I don't really know; I'm just looking this stuff up like you are.

It's dumb that there's no markings on the housing labeling the dials.
posted by aubilenon at 4:51 PM on November 6, 2014

My first guess was that one is a lower temperature bound and one is an upper temperature bound (both for heating).

My understanding is that Johnson Controls made a lot of incredibly complicated HVAC control systems for the 60s and 70s, with central control computers and all kinds of other stuff, so it really could be almost anything.
posted by miyabo at 6:49 PM on November 6, 2014

Response by poster: I found the model number on the blue tab on the top (it was blocked by a shelf).

It's a T-4506. Unfortunately I'm not sure that totally clears up what the two dials are set up to do. "designed to provide individual day and night or two set point temperature control..." Still not clear to me how to use it from the spec sheet I linked before, and it may depend on how the rest of the system is configured, like aubilenon suggested.

At least I'm pretty sure this model can't have the dials set for heating versus cooling temperatures.
posted by spbmp at 8:57 AM on November 8, 2014

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