There are likly more wires on new stat because it is suitable for different applications. If the package say's it's suitiable for cooling only applications,other connections besides yellow,red and green are simply ignored. Screws/connection points on both stats have letters next to each. Before disconnecting wires on old stat,make a note of what color wire go's to which letter/screw then reconnect to new stat accordingly.

Simple wiring - cool, power and fan. Most inexpensive T'stats should work without any problem. You'll need a battery powered thermostat if its digital/electronic.

Thanks for your comments.

I purchased the above mentioned thermostat from HD. After going to my brothers house to install it and opening the package, I found out quickly how soon it will be returned to HD. I read the instruction manual first. It provided no info on how to separate the thermostat from the backing plate. I had great difficulty in separating the two halves to do the installation. I called Honeywell to express my displeasure with this product. Went home, project cancelled.

After doing a search for this model thermostat, I found other people have had the same problem as I. I have own other Honeywell thermostats over the years that have been built with quality. In my opinion, this stat is not one of them. I will return this stat, trying to purchase another Honeywell stat that was not built like this one as mentioned.

Here is a suggestion that may help. Select another thermostat that Home Depot sells in the store. Then go to YouTube and see if someone has posted a video installing that thermostat model. This may help you determine if the installation is easy or difficult.

I recommend a non programmable, you just set the temperature and its done. Programmable requires your life to be on a tight schedule for it to be useful. And, non programmable is easier to change the temperature.

Red is hot, green ground, and yellow cooling. You can open your furnace panel and follow the wire to the control board and see what the wires are hooked to there for proof of what you are wiring is correct (for future reference and different wires)

The green wire is usually the fan control. The old thermostat shown in photo doesn't require a ground. I would be surprised if the green wire were connected to ground.

It is hard to find a non-programmable thermostat with a digital display. If you buy a programmable one, you can set the program to be the same temperature 24/7.

Here's a reference for installing, it doesn't look hard at all - https://customer.honeywell.com/resources/techlit/TechLitDocuments/69-0000s/69-2448EF.pdf I'm pretty sure the battery is only for backup if power goes out to save the settings.

Non programmable digitals are in every store. Probably wont find a cool only digital easily, im sure it is out there just harder to find. My beef with the programmable ones is if you want to turn the temp down one if you do it with the arrow buttons it is only temporary. If you actually want to change the setting you have to change it for morning, day, evening, night for every single day of the week. Which sucks.

He could use the one I listed just has to hook it up correctly and the heat option wouldn't do anything. Thanks for correcting me on the green wire. ^^

Just thought I would mention on the honeywells, they have a hinge on the top and you lift from the bottom and it pops off.

Most programmable thermostats I've seen have a "hold" function that makes it act like a non-programmable.