Top critical review
169 people found this helpful
Easy install and setup, but lacks some user-control of temperature cycle.
on November 16, 2014
I bought this at a local Menards store with assistance of the staff. I replaced an old round Honeywell mercury-switch model. Have the typical 2-wire setup for a very ancient (40 years old?) natural gas forced hot air furnace. I decided to squeeze some savings on the gas bill by lowering the temperature during the workday when I'm never home for 9 hours, and also drop temperature overnight as I like it cooler while I sleep.
Installation was a breeze. I work as an office equipment service tech, so I did not expect any trouble figuring it out, your mileage may vary in that regard though. I had the required small screwdrivers on hand. The mounting template perfectly matched the old round thermostat, so I just reused the old screws in the original holes in the wall. As I customarily do, I did read the installation and setup directions prior to installation.
Programming was also fairly easy. What you have to understand here is that there are 4 adjustable times of the day where the temperature can be allowed to change. Exactly what the amount I needed for my purposes. If you wish for fewer adjustments, just set 2 or more of the consecutive time events to be the same temperature. This is how I handled the weekend program, as I only wanted to lower the temperature at bedtime and raise again in the morning. I left the "away" and "home" at the same temperature as the "wake" setting to accomplish that. Again, you can adjust the time of day for these events in 15 minute increments. I did not see anything confusing about this other than I would forget to push the set button and think I was adjusting the temperature, and instead was changing the time. The numbers being adjusted flash, so that was just me not being observant.
The reason for me giving 3 stars is this: there is no adjustment for temperature on/off cycle. That old mercury-switch mechanical thermostat was designed to turn on the heat a couple of degrees below the set temperature, and turn off heat a couple of degrees above. That allowed the furnace to cycle on fewer times, and not waste fuel warming the heat exchanger each time. This cheap Honeywell digital thermostat turns on the furnace with only a dip of 1 degree F, off after warming to set temperature. My furnace in my 100+ year old home with little insulation started cycling on every 12 minutes for short bursts of heat. Turns out that the temperature cycle is factory set and cannot change. The only way to gain some control of this is to go into the advanced programming features and adjust the "cycles per hour". Default setting was 5 (maximum) cycles per hour, thus the furnace turning on every 12 minutes (5 times per hour). I dropped this setting to 3 (20 minutes wait between cycles) and may readjust to 2 in the future. Naturally, the manual does not explain the cycles-per-hour setting other than generic recommendations for different types of heating systems. I can see this becoming a potential problem with actually causing me to use more fuel than with the mechanical thermostat. I'll just have to monitor my fuel use and re-evaluate later in the winter. I may need to bite the bullet and spend 2-3 times more for a different brand thermostat that will allow me to adjust the heat cycle to something that approximates the old thermostat more closely. Wish I had researched this prior to purchase now. Cycling the furnace on-off more often can also lead to it failing, and I do not see how taking a 3-5 year loan to pay for a new furnace saves me money. Everybody I know that replaced furnaces with higher-efficient models during the 1990's are replacing their expensive furnaces again. Mine keeps chugging along.
11-23-2013: I bought the Honeywell trim kit http://www.amazon.com/Honeywell-50002883001-50002883-001-Coverplate/dp/B00096JC72/ref=cm_cr-mr-title
After installing, I am noticing that the temperature is tracking more correctly compared to a mercury thermometer on a nearby wall. I suspect that the trim plate is isolating the theromstat from the wall surface temperature (which is cool to the touch usually). The temperature is not fluctuating so badly. Furnace is not turning on at regular intervals this weekend. It's also a lot warmer outside, so again time will tell on this.