Auto pilot won't light


Old 11-13-02, 05:07 AM
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Unhappy Auto pilot won't light

Help. My gas furnace has been working just fine for the last two months. We woke up this morning, and discovered the pilot has gone out. I have followed the automatic pilot ignition instructions and nothging happens.

I have a Ducane multi-poistion gas warm air furnace. Model #MPGA100B4.

It was last serviced on 5/14/02. The technician pulled and cleaned the burner and ignitor assembly. He also checked the blower, and gave the furnace a good bill of health.

I don't know how to tell what type of ignition system the furnace has. The installation manual calls it a "hot-surface ignitor" and says it will heat up to an orange glow and ignite the pilot. It says if the flame sensor detects a proper pilot flame, the main burners will ignite.

The user's manual tells me to call a service technician if I can't get the auto pilot to light. What do you think?
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Old 11-13-02, 06:29 AM
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Hello j_wall60 and Welcome to the Heating and Cooling forum and our Do-It-Yourself Web Site.

Chances are the hot surface glow ignitor is too weak to provide a positive source of ignition. Simply because it glows does not ensure it's hot enough to provide ignition. Replacing it may help.

The most likely cause is a weak glow coil. If it's orange in color while glowing, then it is not glowing hot enough to function correctly.

A hot glowing ignitor working correctly will glow an intense bright yellow orange in color. Too much orange, any reddish color or a dull orange means the glow coil is weak. Replacing it should solve the problem.

You can replace the coil yourself. But first unplug the heater. Install the new ignitor bar exactly as you found the existing part.

Glow bar hot surface ignitors are fragile. Handle and install the new part carefully. These parts are a non returnable electric componet.

For more detailed information etc. read the recent postings within this forum. Many questions already asked describe like or similarly related problem descriptions as your question.

These prior postings and any or all the replies offered within them contain almost all the required information needed pertaining to the many potential and or possible problems with the heating unit like your describing.

Additional Suggestions:
Read the manufacturers online web site for product information, problem possibilities, causes and solving methods, part locations, disassembly, reassembly methods, repair procedures and instructions, pictorials and schematics, all or part of which may be available online.

An excellent source for orginal replacement parts is your local retail appliance parts store. Parts dealers are listed in the phone book under appliances.

Retail parts dealers can also help determine what the possible problem may be. Bring the make, model and serial numbers. The information will help to determine the possible problem causes.

Several other resident heating professionals on this type of heating system, replying within this forum, could have additional helpful information, suggestions, advice.

Check back on your question several times for additional replies.

If you need further assistance, use the REPLY button to add any additional information or questions, etc. Using this method also moves the topic back up to the top of the list automatically.

Regards & Good Luck, Forum Host & Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultants & Gas Appliance Diagnostics Technicians.
Old 11-13-02, 12:59 PM
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that model

has a honeywell smart valve if i am not mistaken. have seen the points inside the valve get weak, and found that "wiggling" the connection on the valve itself will make the points and ignitor will then light. this unit has a very small hot surface ignitor, and should be looked at very closely, it may be obvious that it is bad. also, doesn't this model have a 5 year all parts warranty? i believe so, how old is it?

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