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Discussion Starter · #1 ·
New to this generator talk so take it easy on me. :)

I am looking to purchase a generator for backup power for my house. I live in the country, so sometimes it takes a few days to regain power after a hurricane. I do not have natural gas available.

I would like to run my A/C (4 ton, I believe it runs at 5kw?), lights, 2 fridges, freezer, tv, and water pump.

What size would I need? What are the brands to look at?

Thanks so much for the help. I have been driving myself crazy trying to decide on a unit.
 

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Discussion Starter · #2 ·
Also, someone just said that you can pair 2 generators together? Is this safe to do so?
 

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New to this generator talk so take it easy on me. :)

I am looking to purchase a generator for backup power for my house. I live in the country, so sometimes it takes a few days to regain power after a hurricane. I do not have natural gas available.

I would like to run my A/C (4 ton, I believe it runs at 5kw?), lights, 2 fridges, freezer, tv, and water pump.

What size would I need? What are the brands to look at?

Thanks so much for the help. I have been driving myself crazy trying to decide on a unit.
Look at the LRA (locked rotor amps) rating on your 4-ton AC condensing unit. Without a soft start installed, this will be the current it will draw upon each startup cycle. Most portable generators won't give you more than 30-50 amps at 240V.

I have the Honda EU7000is which is rated to supply about 5500 watts continuously, which is about 23 amps at 240V. I have a 4-ton AC unit, but it won't be running during an outage. We have a smaller mini-split unit in the basement we can use to cool down.

You can parallel two inverter generators together to get more power, but that will also use more fuel. Storing a lot of gasoline isn't ideal, so you may want to look into generators that can run on propane as well.
 

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Welcome.

Good questions.

I am looking to purchase a generator for backup power for my house.
....
I do not have natural gas available.
.....
I would like to run my A/C (4 ton, I believe it runs at 5kw?), lights, 2 fridges, freezer, tv, and water pump.
.....
What size would I need? What are the brands to look at?
I would look at 15kw and up units.

With no natural gas your two options are propane and gasoline. Do you use propane for heat/cooking already? If so - it may be easier adding a generator. If not - not a huge issue, just something you have to plan for.

Please keep in mind that in a disaster scenario - such as the post-hurricane back-up power situation you allude to - acquiring fuel is going to be an issue. What fuel can you get - if any? If you can not get fuel and you dont already have it then your generator is a giant paperweight.

With that having been said - if you can do it - get a large propane tank set up for your generator. Propane won't go bad like gasoline will.

A 15kw class generator will run in the range of 4 pounds of propane an hour. So for 24 hours of operation that is 96 pounds of propane per day of operation. Speaking of propane tank sizes - the typical grill size tank is 20lbs. You can get those "portable" tanks up to about a 100lb size (there are larger ones, but they are not generally considered portable or common). 1x 100lb tank, as big as it is, will get you 1 day of generator run time. So do the math. If you loose power for a week that is 7 days, or ~700lbs of propane, or 7x 100lb tanks.

Conversely, propane weighs about 4.2lbs per gallon. So if you had a 250 gallon installed tank on your property that would equate to 1050lbs, 262.5 hours run @ 4lbs/hr, and just shy of 11 days run time.

Installed propane tanks you can have filled by a truck also. That might be the easiest way to get enough fuel to get you going for days in a disaster scenario - if you can get the propane delivery company to fit you in to their swamped schedule.

Before you select what kind of generator you want think about how much work you want to do as an owner. Are you mechanically inclined? Or do you want to open your wallet and pay money for what you don't want to do? If you want to pay money to have things done for you then you will be at the mercy of all the services you require. If you are mechanically inclined and are willing to do the work yourself you will be able to work to your schedule and what is important to you and your family when it is important. If the main circuit breaker fails on your set up during a power outage and you have to call for service - how long are you going to be out of power before the service dude - who is going to be swamped with calls before you - can get to you and help you out? Or if you have the part in your garage ready to throw in and are mechanically/electrically inclined to do the repair you may be out of power for only the time it takes to diagnose what the issue is.

Something else to keep in mind is there are different classes of generators. Are you wanting only emergency power? Or do you want reliable primary power for long periods of time? Your usual portable and home back up "screamer" generators use engines that run at 3600 RPM, are air cooled, splash lubricated (bigger units are likely pressure lubed), and use carburetors as opposed to fuel injection. "Prime use" generators - think building back-up units like what a hospital would have - run at much lower RPM's, like 1800, are liquid cooled, pressure lubricated, and likely have fuel injection. This is like the difference between a lawn mower engine and a car engine. A car engine will last, with proper maintenance, much longer than any small engine will. Then again, you aren't running your small engines around the clock. Except for a generator... When you are out of power for a week can you trust that intermittent-duty engine to run around the clock during that week? What maintenance is going to be required on that engine - and when? Will you have the parts and materials on-hand to maintain that engine so it can survive the constant beating? Or are you going to rely on a service company - who is going to be swamped during the same period everyone else and their brothers are out of power also - to make sure your intermittent duty generator engine is going to survive? If they can't fit you in to their schedule - how are you going to do your own maintenance so you don't blow up your generator and are permanently without power until the grid comes back up?

Lots to think about.

Also, someone just said that you can pair 2 generators together? Is this safe to do so?
Most "Inverter" style generators you can do this. The application is called "parallel operation". The "paralleling" comes from tying the two inverters together so they synchronize the AC outputs together - doubling the power.

You CAN NOT "parallel" rotary alternator/conventional style generators because there is no way to syncronize the AC output. Only inverters can do that because the AC is computer controlled - the computer is what does the synchronizing.
 

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and water pump.
I assume that "water pump" is a "well pump"?

We have a Jaccouzi that runs on 120v at the cabins. That is a pretty hard starting/hard running load. I want to say it is a 15 amp rated pump motor.

In any event, the larger load for you is going to be the central AC. As was previously mentioned - you can get soft-start kits that will decrease the start up load. The "water" pump will add a lot more load to the system, but if you have a generator that will power the AC you will have the power to run the pump - maybe not at the same time. If your AC is running and the water pump cycles that would be a lot of power.

Something else to consider is if the water pump is 120v that is going to pull on 1 leg of the generator. Your AC unit is 240v so it is going to draw power from both legs.

For example - if the water pump is 15a on 120v like the one we have - lets say the AC unit runs 34 amps. That 34 amp draw from the AC unit is on both legs of the generator alternator. If you add in the 15 amps from the water pump (not counting starting load here) that is 49 amps on one leg of the generator (34 + 15). You would need a generator - just for these 2 loads - with a running wattage of (49 x 240)= 11,760 watts*, or round up to 12kw. That will put you right at the 15kw class generator requirement because the generator classes are largely spec'd by peak/starting wattage with lower continuous running wattage ratings.

*You have to factor the amperage together across BOTH legs of the alternator, not one, because the amperage is your limiting factor on the generator - not the wattage. If you were feeding an RV or boat, for example, that only had 120v - a single leg load center as opposed to a split phase dual leg load center like what you have in your house - there is no way to draw the rated wattage of a generator from the 1 leg. You would have to split your loads and "balance" them across both legs. So when you factor loads together to figure up the size of a generator that is required you have to use the amperage combined across 240v in the calculation, not simply the "wattage" added up because the wattage is not the limit of the generator - the amperage is and that affects each leg individually the same as it does both legs combined. When using the amperage in the calculation against the 240v voltage you cover your bases and get the right "wattage" number you need for your sizing. Again, using "wattage" is not entirely accurate to sizing a generator because that in and of itself does not answer the balancing issue. For that you need amperage - most across 1 leg then calculate that against both with 240v.

An example - my 15kw unit is 13,500 watts continuous, not 15,000w.

The higher the running wattage, to a point, the better. If you are at 75-80% of your running wattage rating that would be an ideal range. That way you aren't at full bore on the ratings - it will help the longevity of the alternator and engine.
 

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As you describe, you're looking at some big $$ to satisfy all your requirements. IMHO, review duration and frequency of previous outages to provide a point of departure on what your real needs would be. The central air is going to push you into a large, fuel guzzling unit. Perhaps put a small window unit in one location, fans, or just sweat. If you don't have propane getting a tank delivered, filled, line run to generator location ain't cheap. Gasoline is problematic as to storage but can be dealt with by adding fuel preservative and then yearly using that gas in your vehicle and replacing. How much gas to store goes back to duration of outages. Don't assume you can just refill gas cans locally as widespread outages affect gas stations too. Do you want an automatic system, e.g. the power goes out, generator starts, and power is back? That's the most expensive. Are you able to wheel out a portable, connect via a generator disconnect and only power select circuits, well pump, frig, freezer, etc.? That's the least expensive, but will probably require an electrician to do the wiring. There are connections that use the meter socket and don't require an electrician but are pricey.

A lot of folks get by with a 5KW generator as only the absolutely critical things are powered. Personally get by with a 3500W. The smaller the generator the less fuel consumed. Also, smaller generators should only be run "steady state" at half load to increase their life and minimize fuel consumption.

Ask your neighbors what they have for generators and how they get through outages.

Good luck
 

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If I wanted to power my 4-ton AC unit, I could parallel my generator with a second one and get a soft starter kit for the main AC, but that would mean replacing and rewiring the inputbox and breaker from 30A to 50A.

It would ultimately be cheaper for me to just get a secondary, efficient AC unit for use during an outage.
 

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As Exmar noted, rather than run the whole-house a/c unit, you could run a couple of window a/c units instead if you want to use portable generators. I live in an area that's prone to hurricanes and power loss afterwards. The goal is to have the equipment in order to be reasonably comfortable for the days of power loss that can happen, realizing there will be compromises when using portables. If you want to run everything in the house full throttle, you're probably going to need a whole-house generator in the 15-20kw range. Those are very nice, but also quite spendy.
 

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yea you are better off using a portable room ac unit when on smaller gens.
and using a large bladder tank setup for the well water so you can run for a days worth of water then turn off the power to the pump and run the rest of the house.
make sure to use good quality check valves on that system.
 

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I recommend you buy a Sense product or something similar to get you an idea of how much electricity you use. It's peanuts compared to picking the wrong generator.
 

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yup
best to have a good inventory of the exact power consumption and when!
pm me for a meter panel idea.
i came up with a good cool solution on my system...
easy to read and see what is going on live!
 

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My 2 cents... Its budget vs convenience. A 15-20kw standby unit, will power everything in your home at the cost of ~$15,000. And it will do it automatically. Generator, ATS, 250-500 gallon propane tank.

If $15,000 or more sounds a bit steep the. A smaller portable generator with Appropriate house connection can be had for as little as $1,500. Then it’s just sizing and fueling logistics. As the unit gets bigger and better the price goes up.

Central AC is the biggest monkey wrench in a generator plan. If you disregard central air a 5kw unit with careful load management can handle the home with minimal issue and ease of fueling. 7-8kw reduced load management but complicates fueling.

Personally, I have an eu7000 and a soft start on my Old Tired 3.5 ton central AC. It CANNOT start my unitby itself... If I pair my eu2000 with it, the pair easily starts the AC. This is a last resort ace up my sleeve. I have a 15k btu portable AC unit tht is my plan A.
 

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Discussion Starter · #13 ·
Thanks for all of the info! I am dumb when it comes to this, mainly because I just have zero hands on experience in it.

I have been looking at the following portable generator.




I am assuming these would be safe to run electronics on?

My thought process is to store gasoline at the beginning of season and use by the end of season.
 

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All those are Chinese clones. I'm not saying that's bad, but it could be (especially for spare parts). But the cost of admission to get a Honda EU7000iS is very expensive. The dual-fuel ones are nice for sure.

There is a big difference in noise between the closed inverter models and everything else. Only you can answer if that matters.
 

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Discussion Starter · #15 ·
All those are Chinese clones. I'm not saying that's bad, but it could be (especially for spare parts). But the cost of admission to get a Honda EU7000iS is very expensive. The dual-fuel ones are nice for sure.

There is a big difference in noise between the closed inverter models and everything else. Only you can answer if that matters.

I agree, but these will probably be used MAYBE twice a year.
 

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That Harbor Freight 9500 looks pretty good. There is a dual fuel variation of the unit by a different company for a bit more $$.


If I were to buy a big inverter generator that’s not a Honda, I’d lean more toward the powerhorse 7500.


Remember that all these Chinese generator have very loose guidelines to their power ratings All of which are embellished.
 

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Discussion Starter · #17 ·
That Harbor Freight 9500 looks pretty good. There is a dual fuel variation of the unit by a different company for a bit more $$.


If I were to buy a big inverter generator that’s not a Honda, I’d lean more toward the powerhorse 7500.


Remember that all these Chinese generator have very loose guidelines to their power ratings All of which are embellished.
I see Duromax ads pretty often. I never heard of them. Are they good generators?
 

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None of them are good and all of them are good. :)

There isn't much difference between the quality of the Chinese generators. Champion might be one of the few exceptions. Other than this forum, YouTube probably has the best reviews.
 

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Discussion Starter · #19 ·
None of them are good and all of them are good. :)

There isn't much difference between the quality of the Chinese generators. Champion might be one of the few exceptions. Other than this forum, YouTube probably has the best reviews.
Champion being one of quality?
 

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I can't say for sure that Champion is better than the rest, but they are well respected here. They also stand by their products. The QC should be better.

Someone else may correct me, but I view (portable/inverter) generator quality to go like:
  • Honda
  • Yamaha
  • Champion
  • Clones that use genuine Honda or Yamaha engines
  • Everyone else to varying degrees
 
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