Editing Openai/6937717f-8ef0-8006-a25e-54ade93fb8a7


{{DISPLAYTITLE:Furnace blowing cold air}}

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== gpt-5-1 ==
=== User: I have a fire chief wood furnace? ===
I have a fire chief wood furnace? Looking for advise. The stove will be burning good and blow hot air for 10-15 mins and start blowing cold air. If I open the stove, it is roaring hot. What am I doing wrong? It’s in a pole barn that is not insulated. Why will the stove not pushout the hot air from inside the stove? I’ve tried everything I can think of.

=== Assistant: Here’s what’s going on — and why your Fire Chief wood furnace is blowing cold air even though the fire is roaring: ===
Here’s what’s going on — and why your Fire Chief wood furnace is blowing cold air even though the fire is roaring:

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4

=== ✅ Your Problem in Simple Terms ===

If the fire is blazing inside, but the blower starts blowing cold air, then the air around the heat exchanger isn’t getting hot enough to keep the blower limit switch engaged.

This usually points to ONE of these issues:

=== 🔥 1. Pole Barn is Not Insulated = Heat Exchanger Never Gets Warm Enough ===

A non-insulated pole barn sucks heat away faster than the furnace can produce it.
Even if the firebox looks like hell itself inside, the metal heat exchanger surrounding it stays cooler than normal.

So:
* The blower turns on when it hits “ON” temperature (usually around 120–140°F)
* The barn steals the heat
* The exchanger cools off
* The blower limit switch shuts the blower back OFF
* But the blower on your model probably defaults into a low/auto-cool mode → cold air

📌 This is the #1 cause in pole barns, shops, and big uninsulated buildings.

=== 🔧 2. Blower Is Turning On Too Early (Limit Switch Problem or Bad Setting) ===

If the blower comes on before the furnace body is hot, it will blow cold air until the metal warms up — but in your situation it never catches up.

Check the Fan/Limit switch (usually looks like a metal box with a dial inside):

===== Typical settings: =====
* FAN ON: 120–140°F
* FAN OFF: 90–100°F
* HIGH LIMIT: 170–200°F

If your FAN ON is too low (like 100–110°F), the blower will turn on way too early and blow cold air.

=== 🌬️ 3. Airflow Too Fast — Blower Is Cooling the Furnace Instead of Heating the Room ===

Some Fire Chief models have 2 or 3 blower speed settings.

If the blower is running too fast:
* It cools the heat exchanger faster than the fire can heat it.
* The limit switch kills the blower → cold air cycle.

Try LOW blower speed if possible.

=== 🔥 4. Wood Type or Fire Condition ===

If the fire is visibly roaring but:
* wood is damp
* too much air intake
* fire is too “flashy” (lots of flame, not much coal bed)

…it produces flame but not deep radiant heat.
That means the firebox surface and heat exchanger don’t get hot enough.

You need a solid coal bed, not just tall flame.

=== 🧱 5. Heat Ducts Are Cooling the Air Before It Reaches You ===

If your furnace is ducted in long runs of uninsulated metal pipe:
* the ducts act like radiators
* the hot air cools rapidly
* blower sees lower temps
* cold air output

=== 🧪 Quick Tests You Can Do ===

===== ✔ Test 1: Turn the Blower OFF temporarily =====

If the stove gets really hot, then the blower is cooling the exchanger → blower premature ON or high fan speed.

===== ✔ Test 2: Look at the Fan/Limit switch settings =====

Are the ON/OFF temps set right?

===== ✔ Test 3: Try burning oak/hickory =====

Does the blower stay warm longer? If yes → fire quality/coal bed issue.

===== ✔ Test 4: Stick a magnetic thermometer on the stove body =====

If it never climbs above 250–300°F on the outside steel, the building is sucking the heat away.

=== 🧠 Most Likely Scenario (Based on What You Said) ===

👉 The furnace itself is working fine.
👉 Your pole barn is stealing heat faster than the furnace can make it.
👉 The limit switch is shutting the blower off and forcing cold-air cycles.

You could burn 24/7 and still fight the same problem unless the structure gets insulated or airflow settings get corrected.

=== 💬 Want to Fix It Properly? ===

If you want, tell me:
* Model number of your Fire Chief
* Does it use manual blower control or automatic fan/limit switch?
* How big is your pole barn?
* Any ducting or does it blow straight into the open building?

I can give you exact settings and fixes.

== References ==
<references />


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