Honeywell TH4210D1005 Electronic Programmable Thermostat with Pullout Instructions

We chose this thermostat to control a new installation of a heat pump coupled to a new LPG furnace, replacing my old oil furnace. It works great on the cooling cycle, and also on the heating cycle via the heat pump (haven't installed the LPG tank yet so that part hasn't been tested, but will no doubt work fine. Great to have central cooling, rather than fussing with my old window units. Just in time for the July heat wave here in Indiana. Installation was done by a certified HVAC technician, so I can't speak to the difficulty of installation, other than knowing the tech had no problems.

This is a great functionally equivalent replacement for the Honeywell 8100 series heat pump thermostat. The terminals aren't exactly the same but I was able to figure out what went where by looking at the installation manuals for the old unit and the new one and lining up the functions.This unit is not billed as a homeowner installable (consumer grade) unit but I had no trouble installing it myself on my 2 stage heat, single stage cool heat pump. You'll need to know what kind of system you have, gas heat, electric heat etc but once you have the information you need, this is an easy install.

Replacement for the original thermostat. Exact same model. Plugged it in the wall and it works perfectly.

I had a Lux programmable thermostat before this one, but it had some issues with my heat pump system... so I purchased this as a replacement. I've used it for roughly a month or two now, and it has worked flawlessly.Like the Lux t-stat I had previously, it has four daily programs. During the winter, I have mine set to warm the house before I wake up, keep the house cool when I'm at work, warm it back up before I come home, and cool it down when I'm sleeping. Unlike the Lux t-stat I had, this allows you to have a nighttime setting after midnight. For example, I have my latest setting to bring the house to 65 at 12:30am. The Lux t-stat wouldn't let me do that, because it's technically the next day, but this one accounts for that... which is helpful. You can choose a different set of programs for the weekend. Unlike some programmable t-stats, this one forces you to use the same program for Sat and Sun, instead of having separate programe for each of those days. It's not an issue for me, but it may be for some people. There are other t-stats that allow you to set Sat and Sun separately.If you change the temperature manually, it will override the program until the next time interval that you set. If you decide to take a vacation, you can set the temperature manually, and press the 'hold' button to override the program until you release it yourself.The screen is backlit when you change a setting, so you can see what you're doing at night.Also, a really cool feature that I liked is that the t-stat learns how long it takes your house to change temperatures. Instead of toggling your heat at the time you set it to, it will toggle the heat earlier, so your house reaches the temperature you set by the time you specify. This means if you come home at 6, you don't have to set your heater to turn on at 5.... you set it to 6, and the heater will turn on at the time it learned it needs to turn on to get your house warm by 6.The only issue I have with this is the aux heat. I wish there was a way to fine-tune how the auxiliary heating works. I'm not even sure how it works now - it seems to turn on at random, and not when it makes sense (ie when it's extremely cold outside). I'm not a heating expert, so there may be a reason for this, but my old thermostat seemed to manage it better.In any case, I definitely recommend this if you're looking for a heat pump programmable thermostat - this works on both the heat pump and air conditioning side of things. Haven't tried the AC features yet, but I'm sure it'll be fine :)

Exactly what was needed, with good, speedy delivery. Had it professionally installed as my heat pump has auxiliary heat which kicks in when outside temps. get too low for the pump to work normally. Prospective buyers ahould be aware of this when choosing a thermostat. Difference seems to involve eight wires, instead of five, and makes installation a bit more complicated.