Thermostat all for heat induce draft fan starts glow coil lights and flame up and the blower kicks in heats the house for 3 minuts blower shuts down flame is stiil present for 2 min and blower starts back for 2 minutes and then stops. 30 minuts later it repats the sme procedure again.
This just sounds like a couple of problems. First, your blower is designed to only turn on once the heat exchanger heats up, so the flame will be on for a minute or two before the blower starts. it sounds like your blower is cooling down the heat exchanger too fast and causing it to shut off so it can warm up again...check blower speed for heat, it should be the lowest speed (black wire). Blue=medium speed, red= high speed. second problem could be your flame sensor rod is calcified, you just need to locate this and clean it off with some fine sand paper.it is located in the flames near the burners. Also change your filters, for proper air flow through your heat exchanger.
1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or rubber tube senses the negative pressure produced by the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small metal probe about 1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops with no ignition of gas to heat your home. Your furnace shuts down and goes into a lock out condition until you turn your power switch back off and on again. Then the sequence starts all over again with no ignition of the gas.
Solution:You probably need to purchase and install a new ignitor. I would suggest that you inspect your ignitor closely for cracks.Make sure you do not touch the ignitor with your bare hands. If you do not visually see a crack, then you could have a furnace control board problem or a limit, rollout switch problem. Please see "limits, rollout switches & furnace control boards" further down on this page. The furnace's control board might not be supplying the voltage to the ignitor. If your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then you need to clean your flame sensor with light sand paper or steel wool. You might need a new flame sensor, but most of the time they can be cleaned an will work well after cleaning.
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Ok so here is a sequence of the heater lighting and the solution for your problem...
1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or rubber tube senses the negative pressure produced by the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small metal probe about 1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops with no ignition of gas to heat your home. Your furnace shuts down and goes into a lock out condition until you turn your power switch back off and on again. Then the sequence starts all over again with no ignition of the gas.
Solution:You probably need to purchase and install a new ignitor. I would suggest that you inspect your ignitor closely for cracks.Make sure you do not touch the ignitor with your bare hands. If you do not visually see a crack, then you could have a furnace control board problem or a limit, rollout switch problem. Please see "limits, rollout switches & furnace control boards" further down on this page. The furnace's control board might not be supplying the voltage to the ignitor. If your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then you need to clean your flame sensor with light sand paper or steel wool. You might need a new flame sensor, but most of the time they can be cleaned an will work well after cleaning. Please see the pictures below to help you identify a flame sensor.
Thanks and I hope this helps. Feedback apprec.
1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or
rubber tube senses the negative pressure produced by
the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute
before you hear a gas hissing sound. The ignitor did
not glow, the flame sensor (a small metal probe about
1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops
with no ignition of gas to heat your home. Your
furnace shuts down and goes into a lock out condition
until you turn your power switch back off and on
again. Then the sequence starts all over again with no ignition of the
gas.
Solution: You
probably need to purchase and install a new ignitor. I would suggest that you
inspect your ignitor closely for cracks. Make sure
you do not touch the ignitor with your bare hands. If
you do not visually see a crack, then you could have a furnace control board
problem or a limit, rollout switch problem. The furnace's
control board might not be supplying the voltage to the ignitor. If
your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right
back off, then you need to clean your flame sensor with light sand paper or
steel wool. You might need a new flame sensor, but most of the time they can be
cleaned an will work well after cleaning.
1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or
rubber tube senses the negative pressure produced by
the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute
before you hear a gas hissing sound. The ignitor did
not glow, the flame sensor (a small metal probe about
1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops
with no ignition of gas to heat your home. Your
furnace shuts down and goes into a lock out condition
until you turn your power switch back off and on
again. Then the sequence starts all over again with no ignition of the
gas.
Solution: You
probably need to purchase and install a new ignitor. I would suggest that you
inspect your ignitor closely for cracks. Make sure
you do not touch the ignitor with your bare hands. If
you do not visually see a crack, then you could have a furnace control board
problem or a limit, rollout switch problem. The furnace's
control board might not be supplying the voltage to the ignitor. If
your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right
back off, then you need to clean your flame sensor with light sand paper or
steel wool. You might need a new flame sensor, but most of the time they can be
cleaned an will work well after cleaning.
1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or
rubber tube senses the negative pressure produced by
the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute
before you hear a gas hissing sound. The ignitor did
not glow, the flame sensor (a small metal probe about
1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops
with no ignition of gas to heat your home. Your
furnace shuts down and goes into a lock out condition
until you turn your power switch back off and on
again. Then the sequence starts all over again with no ignition of the
gas.
Solution: You
probably need to purchase and install a new ignitor. I would suggest that you
inspect your ignitor closely for cracks. Make sure
you do not touch the ignitor with your bare hands. If
you do not visually see a crack, then you could have a furnace control board
problem or a limit, rollout switch problem. The furnace's
control board might not be supplying the voltage to the ignitor. If
your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right
back off, then you need to clean your flame sensor with light sand paper or
steel wool. You might need a new flame sensor, but most of the time they can be
cleaned an will work well after cleaning.
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