Concealing a Thermostat
NICK KEENAN
| Posted in General Questions on
I have a room where there’s no good place to put a thermostat. It’s a “great room” and the whole room is its own zone. Basically all of the walls are really nice surfaces, wood wainscot, stone veneer, or big windows. So the question is, has anyone ever concealed a thermostat? Is there a way to cover it so that it still gets sufficient airflow to register?
I’m thinking maybe a nook in the stone veneer with something over it? Like speaker grill cloth? Just spitballing.
Thanks.
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Replies
I haven’t covered up a thermostat but wonder if you could more easily hide a remote sensor. I understand some thermostats support this type of add-on.
Yeah, I'm thinking it might be easier to put a remote sensor in the big room and then tuck the thermostat somewhere else. But that just shifts the question to how to hide the sensor.
Thermostats come with so many different looks and styles, maybe one could be found that would hide in plain sight. If the wainscoting is painted or the stone a neutral color that helps. Speaking just of the minimal look I'm a fan of the Nest, Mysa or the new Amazon smart thermostat, even if the project doesn't call for the 'smart' feature.
Anything you do to restrict airflow of the thermostat will tend to make it read incorrectly -- it will more read the temperature of the surface it's mounted on than it will the temperature of the air around it the way you want. Anything you do that adds thermal mass (sorry DC, I know you don't like that term) around the thermostat will tend to slow down it's response to temperature changes.
Your best bet would be something like a speaker grill -- something with low mass, and something that is very open to airflow.
I think it would be easier to do as others have suggested and use a thermostat with a remote sensor, since the remote sensors tend to be small. Many commercial building automation systems have features like this, but in the residential world your options are more limited. The Ecobee thermostat has a very small remote sensor about an inch square (it mounts with a single screw), and it can also do occupancy sensing with the remote sensor. The big downside is that the remote sensor is powered by a coin cell, so you'll need to replace the battery periodically (about once a year or so in my experience, maybe slightly sooner).
Bill
You want something with a simple hard wired NTC remote temperature sensor (ie Honeywell Visionpro). Since the sensor does not have electronics in it, it can be somewhat covered as long as there is still enough airflow to pick up the room temperature.
The best would be to put it behind a raised trim panel that sits say 1/2" off the wall and is open on the top and bottom. I've done something similar to this, it does work but slower response than fully open. The bigger gap you leave the faster the response.
The thermostat can than be mounted somewhere else, inside a closet or in a cabinet. Be careful as there are length limits for hard wired passive sensors.
Thanks, this is what I'm looking for.
I think open top and bottom an covered on the front gives the right balance of concealment and sensitivity.
Next question I have to figure out is whether the cover needs to be removable.
Note that in regards to the length limits, NTC just means "Negative Temperature Coefficient" -- they are thermistors, devices that read temperature by varying their resistance. That means the resistance of the wire effects the accuracy of the measurement (although it can be calibrated out if you have that option). You can use heavier guage wire to go longer distances.
The commercial enclosed versions of these sensors are pretty small. If you use just a thermistor alone, then Akos' idea of a raised trim panel would work pretty well. I'd use some trim on the left and right sides of the panel, leaving the top and bottom open to allow for convective airflow through the hidden space behind the panel, and over the sensor. Mount the sensor so that it's in the middle of that air space with no rigid connection to either side (so that you don't connect it thermally to either surface). The easiest way to do this is to attach the wire to the structure as far from the sensor as possible, leaving the wire supporting the sensor in the air space.
I would make the cover removeable, just in case you ever need to service the sensor. Just use some small stainless or brass screws, whichever best fits your decor, to make it a sort of access panel. If you want to put in the time, you could make the cover slide into a recess in a trim piece so that you have no fasteners visible.
Bill
NTCs are pretty reliable, but like any sensor it can fail. So at least some provisions for access is a good idea. Also do the future a favor and tag the sensor with the location of the thermostat and the thermostat with the exact location of the remote sensor.
P.S. If you want to get fancy with these, you can wire a bunch of them in an array (2x2 or 3x3) to get temperature averaging in a larger area.
There are a few companies that make linear bar grills with a hinged section, for things like what you're doing. They would normally be integrated into a longer section of bar grill through, to make a visually continuous length of grill that happens to have a hinged access panel along the length somewhere. The bar grills have a lot of open area that should work well for a thermostat, (I'm speculating; I've never tried). So there are ways to obscure something and still provide airflow.
If you want to fabricate your own removable cover for a thermistor or thermostat, counterbore a few holes at the corners of the cover (or wherever makes sense) and epoxy small rare-earth magnets flush into the holes, then add something metal in the wall to mate with the magnets. Or reverse that order, and put magnets in wall, steel on the cover, etc.
Same concept that people use for flush mount speaker grills and many other types of cover plates. Magnets work great for attaching cover plates without fasteners.
Honestly though, if the temperature sensor looks decent (a sensor with a round bezel or whatever, instead of a bare resin-dipped PTC element), integrating into the veneer would probably look perfecting fine if bonded into a round hole. Thermal isolation between the sensor and the surrounding material would be key though, so the transient response of the sensor doesn't become the response of the wall covering material.
I think a small round hole would likely be less noticeable than a cover plate (cover plate plus airgap, etc.), but what I see in my head and what your wall looks like may be completely different animals.
....or get yourself a wireless T-stat.