Furnace Electronic Fuse blew, odd circumstances.

My brother's heat was out. I went over to check it out. He said there was a reshaped coat hangar tied between the gas line and the power feed pipe infront of the furnace door. When he removed it, there was a spark. When he heard the spark, the furnace immediately changed operation. Later we found the 3A fuse on the electronic board inside the furnace was popped. The best we can conclude is the spark blew the furnace. But what is odd is that I can't see static electricity blowing a 3A@24V fuse. The fuse does have 32V limit but still. Also I checked and the gas pipe and wiring pipe are both grounded and at the same potential. We ended up putting a 10A fuse in there since who can find a stupid 3A fuse!?! I think they do that 8hit just to get you to pay $5 for a stupid fuse. a 3A trace can't be that much cheaper than a 5 or 10A trace...
2nd problem was that while we were working, his daughter started taking a shower. That turned on the hot water heater. Then we saw the power exhause fan start turning slowly in opposite direction of the arrow on the wheel. Is that wheel supposed to go in direction of the arrow? We never checked its operational direction so I thought I would ask here. Either the heat was going up the chemney creating a draft and sucking air through the furnace as well, or the exhaust was coming down the chimney and back into the furnace. Not sure which.
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Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
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snipped-for-privacy@ThisOneIsFake.com (dnoyeB) writes:
| We ended up putting a 10A fuse in there since who can find a | stupid 3A fuse!?! I think they do that 8hit just to get you to pay $5 | for a stupid fuse. a 3A trace can't be that much cheaper than a 5 or | 10A trace...
Actually, they probably do this so that the fuse blows before an inherently limited class 2 transformer destroys itself when/if the thermostat wiring shorts. Or possibly the class 2 rating depends on the fuse because the transformer is not inherently limited. Either way, it might really be worth your time to find a 3A fuse...
                Dan Lanciani                 ddl@danlan.*com
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On 20 Feb 2006 21:47:57 GMT, ddl@danlan.*com (Dan Lanciani) wrote:
Either way, it might really be worth

Yep, because now, whatever was causing the 3A to blow is just getting warmer and warmer. Hope the op has his fire insurance paid up since he fixed the symptom, not the problem.
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Al Moran wrote:

Only if its a resistive short. Which is incredibly rare. Either way, the 10A fuse was not intended to 'fix' the situation, its just there because the local store did not have a 3A fuse and it was 8 degrees outside...
I been doing automotive fuseing for about 10 years now so Im familiar enough with them to know the risks.
My main question is about the exhaust fan spinning backwards.
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wrote:

Your an idiot. Do you put pennies behind your screw in fuses in your house panel? You have duct tape holding your sewer line together and a chair proped up against the clothes dryer door? Bubba

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dnoyeB wrote:

Find a stupid 3A fuse. Get a 120V or 240V unit. If no one else has one, go to a television repair shop and they'll probably be able to help you for a buck or two.
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clifto wrote:

This is an ATO fuse, the type in cars. rated only for 32V no where near 120V. Well eventually get one from Radio Shack or ill get one from work... 3A fuse is just silly. Anyway Im concerned about the reverse exhaust fan direction. any opinion on that?
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