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Power went out about 11AM, got a text from the utility, AEP restoration expected by 430 today. Went out to barn and got the Generac 3750, started it up and connected. Currently running an upright freezer, side by side Frig, two desktop computers, flat screen tv, Roku, router, a few lights, and charging a couple of phones. This is an "open frame," non inverter unit. Looked it up and I bought this in Sept. 09 and it's been powering essentially the same things for ten years during outages with no issues.

Not trying to start any range wars as it seems the prevailing opinion here is inverter units for "sensitive electronics." Just suggesting an alternative to spending big bucks for a much more complex unit when it may not be needed.
 

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...Generac 3750...
I ran a Generac 3500XL in the same fashion from 1998 until it broke a valve in 2017, and I grabbed a PowerMate 6000/7500 off a truck at Home Depot while I waited for parts. Still have both units and they continue to impress me with the quality of the power, but my APC SmartUPS will not run on either of them. Everything else does, though.
 

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Tabora, the APC unit needs a relatively stable and precise frequency. My APC UPS system acted the same until I changed to an inverter generator, which solved the issue.
 

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I think as long as you look after your generator and keep it running smoothly, you shouldnt need fancy inverter generators?

No normal UPS will run through a generator, you need a "generator friendly UPS" and they are great, I have one running all my stuff in the main sitting room, so when the power goes off, I dont really notice it. Then before the battery power dies (lasts about 1-2hrs depending whats running) I just hook the UPS to the generator... A brillient idea to having a UPS and a generator if you want no powerloss or interruption.
 

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The issue with most UPS system is the windows are set for utility power. Those windows can be opened on most UPS systems to except the voltage an Hertz differences, as well as the fluctuations. The UPS end product will be the same. Should the issue be transients do to alternator design, a small unity power factor load can be added or in some cases a Cap will correct the gen set wave form enough the UPS will except same.
 

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When I run the UPS on the generator the input readings on the UPS are nowhere near as static as the mains power.
 

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oh yea keep in mind the ups has a quick battery charger too!!
that needs to be in your plan for the current demand while on generator power..
I have larger 1500 apc units that run well on the honda eu2000i units...
but you need to plan for the charger!!
I use smaller 1000 units on the router and phone system and the hvac gear.
 

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@KRE: Good Point! I forgot about the software configuration option. That software was not packaged with the SmartUPS 1500, but was included with the 2200 unit. Both of those units have operated for 10 yrs now.
 

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When I run the UPS on the generator the input readings on the UPS are nowhere near as static as the mains power.
Assuming you're talking about a conventional generator, this makes sense. The stability of the power depends on the stability of the engine speed. This is where inverters have an advantage. They can adjust engine RPMs based on load while still supplying the correct voltage/current in a more stable fashion.

If everything runs well on your conventional generator, then more power to ya! Unfortunately, UPSs and a furnace warranty requirements have limited me to either an inverter, or a higher end conventional standby generator.

LP
 

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hey that brings up a good point and a idea!!
what is your current demand on the furnace??
how about a #buck boost transformer??
they work for when you get in an area where the current spikes and dips are bad...
kinda like a real good ups...
but they are old school magnetic...
and they work!!
at least for transient spikes etc.
might be a cool thing to try after a gen set!!
note they do power soak... or drop the efficiency … or draw power as power loss in heat...

and another question is that is the make and model of the furnace??
must be a late model computer controlled unit.
 

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Tabora, the APC unit needs a relatively stable and precise frequency. My APC UPS system acted the same until I changed to an inverter generator, which solved the issue.
Yes, I know that... I'm just a little surprised that the sine waves from the PowerMate aren't good enough for the APC. Here's what they look like:
 

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You need a quite a steady voltage and hertz output from the generator for a "non generator friendly UPS" to run off it. My voltages are anywhere between 220-245v on my generator, but I have a "generator friendly UPS" so the UPS takes the voltage fluctuation into consideration from the generator and the UPS outputs a lovely rock steady voltage of 240v that I use for my computer stuff. But everything is run straight from the generator and nothing has gone pop so far.
 
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