# does my furnace require 240 volts to start/run?



## yuri (Nov 29, 2008)

Look at the electrical specs/rating which is below the model #. If it has a circuit board they can get damaged by the varying hertz/hz cycles of a generator. Normal power is 60 hz/cycles and generators fluctuate between 56-62. Not a problem for power tools/drills/saws but no good for furnaces. I bought a clean power supply filter for close to $200 from an electronics supplier which smooths out the power and is guaranteed to maintain 60 hz and hook it up between the furnace and generator. You also need to remove the wire to the furnace when the power fails and tee in a plug so you don't backfeed power into the utility and kill a lineman/repair person and be SUED. That is why they have transfer switches for permanent generator hookups in houses and commercial apps. Furnace uses about 10 amps (max) x 120 volts = 1200 watts so a 5000 watt generator is fine. Motors draw 3 to 5x as much power on startup so I am not sure a 2000 watt generator would be a good idea or sufficient, even with the clean power supply filter. They are good for saws/drills/lights/construction tools which is what they are meant for.


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## MajorC (Jan 1, 2021)

yuri said:


> Look at the electrical specs/rating which is below the model #. If it has a circuit board they can get damaged by the varying hertz/hz cycles of a generator. Normal power is 60 hz/cycles and generators fluctuate between 56-62. Not a problem for power tools/drills/saws but no good for furnaces. I bought a clean power supply filter for close to $200 from an electronics supplier which smooths out the power and is guaranteed to maintain 60 hz and hook it up between the furnace and generator. You also need to remove the wire to the furnace when the power fails and tee in a plug so you don't backfeed power into the utility and kill a lineman/repair person and be SUED. That is why they have transfer switches for permanent generator hookups in houses and commercial apps. Furnace uses about 10 amps (max) x 120 volts = 1200 watts so a 5000 watt generator is fine. Motors draw 3 to 5x as much power on startup so I am not sure a 2000 watt generator would be a good idea or sufficient, even with the clean power supply filter. They are good for saws/drills/lights/construction tools which is what they are meant for.


Not a decent reply for the person asking his question. Look up specs on Honda Eu2200i *Inverter *Generator. It offers "cleanest" 60 hz power in the industry. Reads right on box: _"Powers sensitive electronic equipment"_ Tens of thousands of these Honda* Inverter* Generators are powering furnaces and computers all over the world. No clean power filter needed whatsoever, one already installed in the Honda. SMH


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## Self Taught Handyman (Jan 27, 2021)

MajorC said:


> Not a decent reply for the person asking his question. Look up specs on Honda Eu2200i *Inverter *Generator. It offers "cleanest" 60 hz power in the industry. Reads right on box: _"Powers sensitive electronic equipment"_ Tens of thousands of these Honda* Inverter* Generators are powering furnaces and computers all over the world. No clean power filter needed whatsoever, one already installed in the Honda. SMH


Instead of calling someone’s reply not decent maybe actually pay attention. 
That conversation took place in 2011. The Honda Eu2200i Inverter Generator wasn’t available till 2018.


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