It was easy to find reviews for Nest Learning Thermostat (I think because it looks fancier then all other programmable thermostats), but it wasn’t the case for Venstar T5800. I spent some time to collect these reviews for you. Here are the reviews from various customers :
Venstar T5800 ColorTouch Touchscreen Programmable Thermostat, August 8, 2012 (5 stars)
57 of 57 people found the following review helpful
I am an owner of the T5800 and while I’m not a HVAC contractor – I work in a related business. I’m writing this review mainly to refute some of the things stated by the previous reviewer. . . .
The main thing I must say is – if you don’t know what you are doing – hire a professional. I’ve always said “the devil is in the details” and while it may be a breeze to replace a thermostat (all you need is a small screwdriver) there is always a possibility that some little things may (or may not) get in the way of a successful installation.
This thermostat requires a constant supply of 24 volt power, and you must have a wire called a “common” coming from your system transformer and running to the “C” terminal on the thermostat. This “C” wire along with the “R” wire provide the power and they shouldn’t be touched together or jumpered together unless you are interested in sparks, flames, or melted plastic. If you are running a furnace and an air conditioner – and you have 4 wires coming to your thermostat (the most common scenario) – you will NOT be able to use the T5800 out-of-the-box. This doesn’t mean it’s game over. There is a product called “Add-A-Wire” that you can purchase very inexpensively that will allow you to duplex 2 functions on 1 wire and then use the free wire you created as your common. You could also run another wire.
For the reviewer to say that you can just jumper things together is akin to saying you can put a paperclip in an electrical outlet and everything would be fine. Specifically, jumpering “R” and “C” together would most certainly fry your transformer. The fact is – a thermostat installation might not be a DIY project. If you aren’t sure of what you are doing, pay the money to hire a professional, or do a little more research. Don’t criticize the product or the manufacturer because of your own ignorance. It sounds like in this case, Venstar bailed this person out. Kudos to them as they really weren’t on the hook to do anything (IMO).