I haven’t move the settings on my very old rectangular Honeywell thermostat since I bought this house. The temperature was comfortable for us, or our guests. The litle arms on the right are set fot 64F, both for day and night, the temperature in the house is 68-69F, according to the thetmostat needle. Recently I touched the case of the thermostat and it felt minimally lukeworm. I, being a skeptic, touched it again with my lips: it was lukewarm.
So, I put two thermometrs next to it, a classic Farenheit kind with red fluid and a needle kind (what’s its name? thank you). They both showed 66F.
So, my thermostat, like any electric device, gets warmed up. That’s probably normal. But then, what does it measure? Its own temperature? Slightly influenced by room temperature?
As I said, we are comfortable, do not wear sweaters at home, and I actually do not care what that little needle shows. But is this how they all function?
All thermostats are adjustable to correct for errors.
None I’ve ever had at the hardware store read the same as the next one of the same brand. If it reads a few degrees off, you can correct it, or like most people just set it to whatever number makes you comfortable.
This number would change from place to place within the house anyhow.
This is usually a minor screw on the number dial, if it’s a bi-metalic strip, or a slide on the coil.
They shouldn’t feel warm. Modern thermostats operate on milliwatts.
Not usually, no. Most low voltage (24 volt) residential thermostats operate a gas valve or a relay that will be rated to draw from about .2 to 1 amp, with the majority in the .3 to .5 amp range. This means most operate in an 8 to 12 watt circuit.
Now having said that, the main purpose of a thermostat is to switch something off and on, and isn’t a load at all, which doesn’t use any wattage, milli or otherwise.
However, most thermostats also have what’s called a “heat anticipator”. In non-electronic stats such as described in the OP (If its a rectangular low-voltage Honeywell, it probably some variation of a T834, the model numbers are printed inside on the base or the cover) the anticipator is a small heating coil that winds up in series with the main load when the stat is on.
The anticipator heats up the inside of the thermostat a little faster then actual air temp in the room. This helps to overcome the mechanical lag in the stat and the latent heat in the heating unit, and makes the stat respond a little faster then it would otherwise. It “anticipates” the heat that will be added to room after the stat turns the main heat source off.
Now IIRC, the heat anticipator only drops a volt or two. At .5 amps, that would give you between a half and one full watt dissipated inside the stat.
I don’t ever recall a stat actually feeling warm to the touch, but I guess half a watt over a long time might do it.
All this from the “more than you ever wanted to know about thermostats” department.
Ugly
Tx, guys. Half a watt or whatever, it’s warm. At least it’s warmer than the air around it. And it does no harm: as a stat, it does its job. The house is comfortable, the heating system is OK, my heating bill is at the bottom of my expenses, even this year. It’s still less than taxes (is the government going to provide some tax-relief as it did for fuel prices?. It would be easier, just release some money from Strategic Defence Programs), food, medicines, etc.