CT87K1004 The Round Heat Only Manual Thermostat,Large,White,Large

Very easy to install

Easy to install work great very happy

POS!!!!! DO NOT BUY THIS!!!!! I bought one, followed the instructions and installed it. Seemed simple. Didn't work, ok, it faulty, returned it for another one. Didn't work. Went to the local hardware store, bought the same model, didn't work. Honeywell is not the same company of 50yrs ago and sells crap. Installed another brand and works perfectly. My system is gas, steam heat only. Two wires. The old unit is Honeywell from 50yrs ago, murcury system. Should be simple, do better Honeywell.

Love this. So much easier to use. Can be more accurate with temperature control.

See the review by John, 2-17-13 for an explanation of the (rare..) use of the 10+ year-life battery inside, as is there to 1) reset after a power failure and 2) initially after install: to charge up a capacitor which actually feeds the internal electronics and which is constantly replenished by the 24-28 V. AC power delivered usually by the furnace electrics when its own power is on (24/7.) Those 24~28 Volts A/C come via a small step-down transformer usually located within the furnace box. That said, recently I did have an -87K unit fail after some 4-5 years (I have no *reliable* info on the failure rates on the hundreds of thousands of these units in service, and individual guesstimates are useless/just gossip.) As I “do electronics” I naturally performed a necropsy on unit. The nominal 3 V battery in that was near-new at 3.22V on a Fluke prof. meter; it did not die via “battery failure”—see above, again—the few occasions where its small power input would actually be missed. I still wanted the natural simplicity of the glass-sealed mercury capsule, but I do realize that the mission of a thermostat/in 2018 is trivial to design and I Saw that the circuit board in my failed unit is comparable quality to that seen in prof. grade test equipment: so I was just unlucky in this early failure (most failures happen on initial turn-on, then ..during first days/weeks until: they go a long….time and then fail for complex reasons.) Four or so years IS … unexpected. Hence the 4-stars, pending.. I just bought another -87K unit from Amazon. It was a 3-second “drop it in and carefully press down till it latches” operation (no wiring had to be done.) I left it alone with temp turned all the way down for 5 min. or so: letting that capacitor charge up to its working voltage from the battery. While it’s only been a couple days, it is doing exactly what you want it to do: silently switch on the permission for furnace to take over. Note that: the manner/temperatures at which the furnace decides finally *to turn OFF* its blower motor is Not anything to do with the thermostat’s ON/OFF decisions: a variety of means are engineered within furnace controls to cover this so-called “hysteresis” time + temp process. Your thermostat is an ON/OFF switch ONLY. I’ll drop in and modify this report should this new unit fail shortly (unless, of course: many are already in caves, say? No reports then. No furnaces either.)

Works properly. Decent price. Very easy to install. Looks great. Would purchase again.

Easy install and works fine - steady temp in my rooms.

It’s losing a star because the other one was only two years old and broke. It’s easy to install. Manual, so no programming. The price is on the low end and temperature control is self explanatory. But I’ve replaced two of them to date and both were approximately 2 years old. So, a bit annoyed.