Gas and Oil Home Heating Furnaces - thermostat

Hello. The rental mgr of my home had the thermostat replaced. The Coleman gas wall heater requires a milli thermostat, which was installed. I just read in one of the posts that the volts in thermostat and heater should match. The heater wasn't even looked at, a new thermostat was just put in. The new thermostat is very erratic and comes on, goes off in a minute or two. Comes on when the temp it shouldn't and stays on after it should shut off and vice versa. A White-Rodgers, type 1C20-102, Rel.A, E1 0234 was installed. Could the thermostat be installed incorrectly or the wires attached to the temp measurement things (sorry) be incorrectly attached? I see that there are what look like two ground wires attached to two of the screws holding the thermostat on the wall. There is a white wire which goes from the bottom left corner to a circle that looks like it has something like "Longer cycles" (can't read all of it) and some numbers on it and a metal arrow like arm. Then there is a yellow wire that goes from the top left corner to this same device. I think I understand that the white wire is sending the room temp to the 'whatever' while the yellow wire then sends a message to the furnace (or turns it on). What is circle with the numbers and words for? I hope this makes sense. Thanks you.

the heat anticipator. it gives the tstat a false signal (heat) to prevent excessive temp swing. search previous posts for more info

By milli I think you mean a millivoltage thermostat? A lot of gas fired wall heaters use a 750 millivolt [3/4 of a volt] Powerpile system to operate the gas valve and they need a special thermostat for that application. The Honeywell # TS86A is the one to use. It has a fixed heat anticipator; you can't use a thermostat with an adjustable heat anticipator on a millivoltage system. The new thermostat is the wrong one. Print this post and show it to your landlord.

Thanks Big John,
I don't think my landlord will really care too much, it was difficult just getting a new thermostat. If I buy the one you recommend, would it be simple enough for me to install? Personally it doesn't look to hard. Sadly I had a retired "expert" put in my milli thermostat (you were correct). I wondered how he could buy a new one without ever looking at the present one or checking out the heater. Oh well. Life's interesting.:)

Your landlord won't care if you have heat? I'll bet there is a government agency or newpaper reporter who will. You could install the thermostat yourself if you want, not difficult at all. To see the installation instructions in advance, go to http://hbctechlit.honeywell.com click on agree, then on the next page select model & all literature, type TS86A into the search box. You can download the installation instructions from the next page.

Thanks again Big John,

It isn't that I don't have heat, it's the fact that I either have too much or not enough. Just now the heater kept running and running. I checked the thermostat and the temp was about 74, but it is set on 68. So, to turn it off, because it was pretty hot, I had to turn it down even more. In consequence, it has to get pretty cold before it kicks in. Just a lot of running back and forth to either get more heat or less. Maybe I should move to Hawaii. Their coldest day ever was 52. Sounds good to me.