Gas and Oil Home Heating Furnaces - No heat
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hkanda
08-03-02, 12:42 AM
I have a central AC/Heat unit. The A/C works fine but the heater does not. When turning on the heater, there is no heat coming from the heater. Any help would be appreciated...
bigjohn
08-03-02, 05:46 AM
Youcould try resetting he power to the furnace and see if that restes something. Could you give us an idea of what type of heating unit [gas, oil, electric, heatpump, boiler??] you have and how old?
hkanda
08-05-02, 01:25 PM
I have a gas heater and the furnace is 4 years old...
kaybyrd
08-05-02, 02:01 PM
I turn off the gas to the furnance during the summer, maybe the gas got turned off, or the pilot light is out.
Kay
Kay
bigjohn
08-06-02, 07:22 AM
Great suggestion! It's easy to overlook the obvious. A furnace as new as yours won't have a standing pilot. It most likely has a Hot Surface Ignitor [HSI for short] and an integrated furnace board. When furnaces first started to get complicated, they had a circuit board for each function. Now, all the operating & safety functions are combined into one board or module. Here's the sequence of operation:
1. When the t-stat calls for heat, the inducer motor starts
2. The pressure switch closes
3. The ignitor glows red hot
4. The gas valve opens and the burners lite
5. The buner flame is proven
6. The burners continue to fire as long as the t-stat calls for heat
7 When the t-stat is satisfied, the gas valve closes shutting off the flame
8. On some models, the inducer motor continues to run for a post prurge and on some it shuts down when the gas valve shuts down
Some where with 5 and/or 6, the indoor blower starts. On most models, the indoor blower runs for a time period after the burners shut down. The modules usually have a little light which will flash a fault code. The code explanation should be on label on the inside of the cover or inside the furnace. Assuming the gas is on and the t-stat is not malfunctioning, look for a fault code and/or check for this sequence of operation. Most common failed parts?- the ignitor and the pressure switch.
1. When the t-stat calls for heat, the inducer motor starts
2. The pressure switch closes
3. The ignitor glows red hot
4. The gas valve opens and the burners lite
5. The buner flame is proven
6. The burners continue to fire as long as the t-stat calls for heat
7 When the t-stat is satisfied, the gas valve closes shutting off the flame
8. On some models, the inducer motor continues to run for a post prurge and on some it shuts down when the gas valve shuts down
Some where with 5 and/or 6, the indoor blower starts. On most models, the indoor blower runs for a time period after the burners shut down. The modules usually have a little light which will flash a fault code. The code explanation should be on label on the inside of the cover or inside the furnace. Assuming the gas is on and the t-stat is not malfunctioning, look for a fault code and/or check for this sequence of operation. Most common failed parts?- the ignitor and the pressure switch.