# How much current should my gas furnace be drawing?

**URL:** <https://boards.straightdope.com/t/how-much-current-should-my-gas-furnace-be-drawing/386660>\
**Category:** Factual Questions\
**Created:** [January 4, 2007, 7:24am UTC](https://boards.straightdope.com/t/how-much-current-should-my-gas-furnace-be-drawing/386660 "2007-01-04T07:24:20Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\
**Post date:** [January 4, 2007, 7:24am UTC](https://boards.straightdope.com/t/how-much-current-should-my-gas-furnace-be-drawing/386660/1 "2007-01-04T07:24:20Z")

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I’m not paying a stupendously high amount for electricity ($8 for administration fees, $14 or so for the actual juice last month) but I’ve noticed that my furnace seems to draw quite a lot of current, at least compared to anything else I own.

I was checking that little spinning wheel dealy on my meter, and with my low-end Linux box, dual Xeon PC and 21" CRT (300 - 400W together I’d guess) running, plus a bunch of CFLs turned on, it made one revolution every 40 seconds. When the furnace kicked in, it turned once every 20 seconds or so.

I’ve only been here 4 or 5 months so far, so I really don’t know what ‘usual’ useage is, but does that seem normal? I have a clamp multimeter that I don’t know how to use lying around someplace if anyone recommends its use.

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**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\
**Post date:** [January 4, 2007, 8:11am UTC](https://boards.straightdope.com/t/how-much-current-should-my-gas-furnace-be-drawing/386660/2 "2007-01-04T08:11:52Z")

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Go look at the data plate on the furnace. It should list the normal amperage draw for the fan motor either on the furnace plate, or on a plate on the motor itself.

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**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\
**Post date:** [January 4, 2007, 1:56pm UTC](https://boards.straightdope.com/t/how-much-current-should-my-gas-furnace-be-drawing/386660/3 "2007-01-04T13:56:23Z")

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[Here is a list of power consumption for appliances.](http://www.city.ames.ia.us/ElectricWeb/energyguy/appliances.htm)

It says the average furnace will cost you between $4.20 and $10.80/month to run.  
350watts is equivolent to about a 1/2 hp motor. Furnace motors are not known for being terribly efficient, that’s why some go with DC units that use drives to control the blower.

I would not recommend using the meter on 120 volts unless you were very comfortable doing this and I would still be hesitant to walk someone through it.