We have an old Airco forced air gas furnace, model #HBS2-100/90. We've been having a few issues lately, so I'm looking for some opinions. I haven't found a date stamp on the furnace, so I'm assuming that it's at least 20 years old.
The furnace has two wires going to the thermostat (red & black). There are more wires available in the wall, but are not connected at either end.
Our thermostat was a battery powered 7 day programmable unit and did the job, although I didn't really like it. Recently we were finding that the heat was staying on longer than expected and the house was warmer than we had the thermostat set. After new batteries and trying a few different programming settings we decided that the thermostat was failing.
At this point we installed a mechanical (mercury switch) Honeywell thermostat that our father had stored in the garage. With this installed, the burners come on for about 45 seconds, they shut off then the blower comes on for about a minute, then shuts off. This repeats every couple of minutes. Definitely NOT what we want.
I just jumpered the red/black wires today and the burners and blower ran the whole time without shutting down, so the furnace isn't overheating or anything like that.
At this point I figure we just need to buy a new thermostat. Since I'm doing this I'd like to use one of the wires to allow the blower fan to be controlled by the switch on the thermostat - currently I need to open the furnace and push in a button. I'd also like to run a 24v(?) line from the furnace to power the thermostat instead of depending on batteries.
Sounds doable so far, right?
Now my questions...
- On the inside of the mechanical thermostat there is a dial, or heat anticipator. Adjusting this didn't seem to make any difference to our issues. Would an issue at the furnace affect this and throw the mechanical thermostat out of whack? Would the same have happened with the original electronic thermostat?
- There are no terminals on the fan controller in my furnace. It's just a metal box with Honeywell stamped on it and three wires coming out (Red, Black, Blue). Is there a simple way to add wiring to this to control the fan from my thermostat fan switch?
- Finally, to bring the 24 volts up from the furnace, what wires would I use? There is a black box attached to the side of an electrical box inside the furnace. I assume that this is where the power goes from 120v to 24v. The wires coming out of here are black and yellow. The yellow wire here connects to the gas valve and to the black wire going up to the thermostat.
I can provide photo's or other info if necessary... just not sure what is important and what isn't.
Can someone provide some help?
The furnace has two wires going to the thermostat (red & black). There are more wires available in the wall, but are not connected at either end.
Our thermostat was a battery powered 7 day programmable unit and did the job, although I didn't really like it. Recently we were finding that the heat was staying on longer than expected and the house was warmer than we had the thermostat set. After new batteries and trying a few different programming settings we decided that the thermostat was failing.
At this point we installed a mechanical (mercury switch) Honeywell thermostat that our father had stored in the garage. With this installed, the burners come on for about 45 seconds, they shut off then the blower comes on for about a minute, then shuts off. This repeats every couple of minutes. Definitely NOT what we want.
I just jumpered the red/black wires today and the burners and blower ran the whole time without shutting down, so the furnace isn't overheating or anything like that.
At this point I figure we just need to buy a new thermostat. Since I'm doing this I'd like to use one of the wires to allow the blower fan to be controlled by the switch on the thermostat - currently I need to open the furnace and push in a button. I'd also like to run a 24v(?) line from the furnace to power the thermostat instead of depending on batteries.
Sounds doable so far, right?
Now my questions...
- On the inside of the mechanical thermostat there is a dial, or heat anticipator. Adjusting this didn't seem to make any difference to our issues. Would an issue at the furnace affect this and throw the mechanical thermostat out of whack? Would the same have happened with the original electronic thermostat?
- There are no terminals on the fan controller in my furnace. It's just a metal box with Honeywell stamped on it and three wires coming out (Red, Black, Blue). Is there a simple way to add wiring to this to control the fan from my thermostat fan switch?
- Finally, to bring the 24 volts up from the furnace, what wires would I use? There is a black box attached to the side of an electrical box inside the furnace. I assume that this is where the power goes from 120v to 24v. The wires coming out of here are black and yellow. The yellow wire here connects to the gas valve and to the black wire going up to the thermostat.
I can provide photo's or other info if necessary... just not sure what is important and what isn't.
Can someone provide some help?