Yesterday, a gas wall furnace was removed and is being replaced with a gas fireplace. Is it possible to hook up the thermostat that was used for the furnace to this fireplace? The only writing on the unit is "Insta-Flame CFM.

As far as I know, there will be a regulator switch, sort of one and of flame adjustment. I don't think it is thermostat controlled.

I hope you didn't let that first post discourage you. The fireplace may not have come with a thermostat, but you can add one. You will have to put back all the parts from the wall furnace or new, similar ones. Likely it had a milivolt gas valve powered off the tiny voltage produced by the thermocouple in the pilot light. The thermocouple connects to the thermostat. The thermostat also has a pair of wires going to the gas valve. Power flows from the thermocouple through the thermostat to the gas valve. When the room is above the set temperature, the contacts in the thermostat open, breaking the circuit, shutting the gas off.

You need to rescue the thermocouple and gas valve from the furnace. If you can't, then buy new. I am not sure how common millivolt systems are now. It may be tough finding new parts.

Northern Heat, T-Top, and Acetc should know more about millivolt systems than I do if you need more help on some of the details. I would be just as happy to leave all these questions to those knowing more than me. Unfortunately, I often feel I need to jump in after somebody knowing less than me misleads somebody.

Why was my post discouraging, misleading and when will you stop villifying me labman, this was not a dog post after all? I wasn't talking 'out of my hat', I used to have one and that is how I used it. My neighbour has one and uses theirs the same way, for comfort heat and not necessarily a heating source as she has a gas furnace. Their gas fireplace is a lovely addition to their family room.

I will leave it to others to judge.

Do not feel bad tickle good old labman just has a few strange thoughts. Someday one of his non listed and labeled repair answers will hurt someone. You are not supposed to modify/change the operating safetys or controls on equiptment because UL/CSA has not tested it with the modifications. That makes it lawsuit heaven especially when you are telling a homeowner who has no idea what you are talking about does the work. labman does help many people but sometimes he feels that we do not go far enough to tell people how to hurt themselves. LOL I am off my soap box now. LOL

I too use a thermostat on my fire place and would like to add some input. I have found that the milivolt of electricity that is produced off the electronic thermocouple in the fire place is so tiny that the thermostat or switch you use can make a difference and beware keep the wire run as short as possible or better yet go with the manufacture recommended wireless remote stat. I say these things because I have seen so many failures due to dirty contacts or bad connections and or to small / to long of wire runs/ the recommended parts will have like gold contacts and ways to improve better communications in a low voltage condition to your fire place. Long wire runs over small wire will cause bad voltage drop in a already low voltage condition .
So to make a long story short I would say buy the wireless remote , hang it next to the old remote.
If that is too far from the fire place to work you will have to relocate the remote.