Ward 5700 Floor Furnace on the the Fritz!


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Old 12-29-12, 10:46 PM
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Ward 5700 Floor Furnace on the the Fritz!

Have a 1950's Ward model 5700 Floor furnace that has been giving some trouble over the years. House was built in 1950 in Los Angeles County along the foot hills

At first it would not light unless the T-stat was set 15-20 deg higher than the current temp. Would fire up if the two wires were jumped to make contact and over all worked as needed but of course with the temp set higher than needed would get a little to too toasty on some nights.

This week, could not get a response from the furnace, so jumped the wires and it would ignite. The old T-Stat had been replaced about 12 years ago, but was looking a little beat up and since it had been giving problems for the last few years, figured it was time to replace.

Installed new one and set the temp and furnace ignited with in a seconds. Figured the problem was solved.

Today I noticed that someone had turned the T-Stat all the way up and was not lighting. moved the T-stat through the range a couple of times but no ignition. Pulled the T-stat from the wall to check the wiring, and got the furnace to ignite. Cycled the T-stat 2-3 times and it seemed to work. I re-installed the T-stat on the wall. Went to cycle the T-Stat to ignite again and no dice.....

Pulled the T-stat off the wall yet again and checked every thing, but still no fire. I jumped the wires and was able to get the furnace to ignite. Jumped a second time and no fire. A couple of more tries, ignition and has been intermittent (however slight) with a direct jump. I fear that the valve is shot.

Where to find replacement gas valve for such an old beast?
Thanks in advance for any help anyone can provide.
 
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Old 12-30-12, 01:52 PM
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Does the floor furnace have 120 VAC powwer to it? A lot of floor furnaces do not.

They use power generated from the heat of the pilot burner flame to generate thye power needed to operate the gas valve. In such a furnace, the most common reason why the burners wont light is that the pilot burner and pilot orifice are dirty and not providing sufficient heat to generate the electricity needed to turn on the gas valve.

Describe the appearance of the pilot flame. It should look like a small blowtorch and engulf the pilot generator that should be in the flame.

A dirty pilot burner will have a flame with yellow tips, or a lazy blue flame easily blown around like a candle flame.
 
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Old 12-30-12, 01:59 PM
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I can't find any info on that furnace.
Are you sure it isn't time to replace that 60+ year old furnace

As a guess based on older systems like yours....it's either a gas valve problem or a weak thermopile.
 
 

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