Would like to know if I will be able to install a Honeywell RTH7500D1031 with my gravity furnace. I have upload pictures of my current thermostat and furnace. Please let me know if you need more information about my equipment. I am concerned due to age furnace that I may have better luck leaving it as is. Pictures of them/furnace http://imgur.com/a/uO6kw

There can be several reasons for this, the thermostat may be working fine but the heater or furnace may cause a lapse in response.

Thermostats don't actually blow anything, the heating system might though. Check the breakers for your heat system, then call a heating specialist. They're really not that expensive.

If the thermostat is battery powered you are ok just hook up red and white terminals it doesnt matter which one goes where if it is heat only

hook up the blue wire in the furnace cabinet where the blower section and the other thermostat wires are connected to the furnace. the thermostat you have uses a common wire from the thermostat to the furnace and this needs to be hooked up in the furnace otherwise you will have the problem you are having.

HONEYWELL WEBSITE:
Go to honeywell.com
Under red welcome sign
Bottom red highlighted box literature/image search
Type in thermostat model number
Click on arrow to right
Then click on the PDF files owners manual / installation instructions

the 230 doesnt sound compatable with your system. you are gonna need a t stat that is compatable with Heat Pumps.

check your heat antisipator setting make sur eit matches your tpye of heat. also, do you have a 2 stage heating sys?

I currently have a 2 wire system. I have one red and one white. I hooked the red to the R and the white to the W. I had to go into the system setup using the UP arrow button and the FAN button. The first setting is the 1 setting, and I selected number 2 ( Heating Only ). Then the 5 setting. I selected number 1 ( Gas/oil steam or gravity system ). Then 14 is usually 0 for Fahrenheit. I was just messing around and that is the buttons I used and I tested it. The furnace kicked on and then 10 to 15 secs later the air began to blow through the vents. I hope this works for others who read this.

Sounds like a relay sticking. Possibly in the thermostat or possibly the furnace relay at the furnace. The next time it happens, unplug the thermostat from the wall. If the furnace still runs then it's the furnace relay.

Hope that helps...

Geno