Thermostat wiring?

[joshhudm]

So boiler is having a problem and it keeps turning on and off. Had a guy out to look at it and he also noticed that our thermostat isn't showing the temp correctly. Since this is a relatively easy project i decided to take the old analog one off and put a digital one on. Well i took the old one off and found this mess. When i looked up installation directions i read there should be a green, blue and yellow. Well only the red and black were attached and i also see i thicker gauge black and white wire tucked away. Could someone make sense of this for me?

i attached a picture i took with my phone

[paul52446m]

So boiler is having a problem and it keeps turning on and off. Had a guy out to look at it and he also noticed that our thermostat isn't showing the temp correctly. Since this is a relatively easy project i decided to take the old analog one off and put a digital one on. Well i took the old one off and found this mess. When i looked up installation directions i read there should be a green, blue and yellow. Well only the red and black were attached and i also see i thicker gauge black and white wire tucked away. Could someone make sense of this for me?

i attached a picture i took with my phone

Well i don't know if we can make any sense or not but lets start working on it. The two large black and white are there because they used to have a line volt stat for elect heat? or they used a switch box and converted it to a stat box. You will have to read your new stat info , some stats need 24 volt coming to them. other wise all the stat does it makes a switch to turn the heat on which is just two wires. Does
the stat go to the t&t post at the boiler. You do not have zone valves ?
If your stat only makes t&t at the boiler then you only need two wires, but if your new stat need 24 volts to it then you will have to run a new wire so you can get a transformer common to the stat. When you turn your stat all the way up did your boiler keep going? You might have a problem with your boiler
and not your stat. Put those two stat wires together and see if the boiler keeps going? Let me know. Paul

[joshhudm]

There is definitely a problem with the boiler but i would like to put a newer stat up since this is an old analog one. Im guessing it used to be a switch box. If the new stat just get power from batteries i should be fine and it will be used just for heat. As far as i know this place was always heating with hot water baseboards. I shouldnt have a problem putting up a digital stat right?