Generator size

Discussion in 'Energy & Electricity' started by Wiswash, Aug 29, 2010.

  1. Wiswash

    Wiswash Active Member

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    Hi, I am new here so maybe this topic has been covered before but its vital information anyway. I am in the market for a home generator, for emergency purposes but first i want to figure out what size I need. Do I look for a gen according to watts, volts or amps??

    Here are my needs. In the case of a long time outage of a few months or more I have plenty of wood fuel for heat and propane for cooking and a few lanterns for light. I live in a semi rural area and use a well pump (220 volts) and an injector pump in my septic system. My largest need for a generator is to power the well pump. Powering the refigerator and chest freezer would probably be essential too. At this point I have all my basic needs for my family including food, water and shelter. Electricity for anything else would be nice but is essentially a luxury.
    I would look for a quiet engine. Ive noticed Honda engine gens seem very quiet. And I would probably run this gen a couple hours per day at most, just to get enough water and chill the refer and chest freezer for the next 24 hours, or so. Many thanks for your advice.
     
  2. ZoomZoom

    ZoomZoom Rookie Prepper

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    Welcome to the forum.

    For your needs, it sounds like you'll need something in the 5KW range (5000 watts). You may be able to go a bit smaller but you may have a hard time finding something smaller with 220v. You also don't want to overload the generator. It's best to run them at about 50-75%. They can take surges but they're not going to like running at 100% all the time.

    I have a similar setup with well and septic.

    For your well pump:
    A well pump is normally 3/4 to 1 HP. 1 HP = 746 watts. It takes about double that to start the motor so you'll need a surge capability of 1500 watts for that.

    Sewer pump:
    Normally 1/2 HP. Let's plan 750 watts for that.

    Fridges/freezers:
    Depends on size and age. The older ones have larger HP motors but don't run as long. Newer ones have smaller motors but run for extended periods.
    Let's say 1/3 HP each. Let's plan on 1000 watts for that.

    OK, lets tally.
    1500 for well pump
    750 for sewer
    1000 for appliances

    3250 watts. Now, that's figuring surge but after things are running, that will go down to almost 1/2 of that amount.

    You still have plenty of power to run lights and such. Depending on the situation, you may want to have a TV or radio running. If you don't have a large microwave, you could probably run that as well.
     

  3. NaeKid

    NaeKid YourAdministrator, eh?

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    I agree with bczoom about that minimal power requirement but I would like to toss another idea into the mix.

    My buddy just bought a generator for his acreage that does more than just create power for the house - it is also a stick-welder, mig-welder and tig-welder all rolled into one. He can run his entire shop off of the welder/generator (grinding tools, air-tools through compressor, etc). Driving the truck (with welder mounted to the back) allows him to repair his drilling-pipe fences, run the whole-house and head out to neighbor's places to fix-up their little projects (and get either brownie points or cash).

    A dual-purpose system might do you a little better, especially if you have ever needed to fuse two pieces of metal together.
     
  4. Wiswash

    Wiswash Active Member

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    Thanks guys, for getting me started. I eventually went to the Honda generator web site. Theres a lot of info there to sort thru and its educational, too. It is also possible to use 2 generators of the same model to supply the power Looks like I would have to spend 2-5 grand, eesh!! I also found a Craigslist ad for a Ram Power generator, for much less money. I wonder what the quality of Ram Power is? There is certainly lots to consider when picking a generator, besides power demands. Decibels, fuel efficiency, transfer switch, unit weight and portability, affordability all need to be looked at. Some people believe stealth (decibels) is an issue and at this point I would agree. If anyone has any opinions on differnet brands/models I would love to hear them. Thanks

    NaeKid, I dont know my mig from my tig so i will have to forgo the welding needs. Thanks anyway.
     
    Last edited by a moderator: Aug 30, 2010
  5. NaeKid

    NaeKid YourAdministrator, eh?

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    Not a problem about not knowing welding, it is a skill that not everyone needs.

    As for your comment about stealth-running of the gen-set, there was a post about that here. Someone commented that putting the gen-set into an insulated shed (sound insulation) and then running the air-intake through the wall (pre-filtered) and then running the exhaust through rain-barrels full of water so that the only sound is a wooshing of air going into the gen-set and a "bubbling-brook" sound from the exhaust.

    I haven't tried that, so, I don't know how well it works, but, it is a thought for you to consider.
     
  6. nj_m715

    nj_m715 www.veggear.blogspot.com

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    Read the tags on the thing that you need/want to run. Only you know what you how much power you need. Remember that they don't have to run all at once. you can unplug the fridge to run the water pump etc. and that will let you get away with a small, cheaper, more portable genset. It doesn't need to run all day either. turn it on, pump the water, take showers, fill drinking jugs, chill the fridge then turn it off for a few hours. The food will stay good, just watch the temp. Your fridge doesn't always run anyway, it turns itself off and on.

    Think about charging some batteries for lights, laptops or other small items while the gen set is off through the night.
     
  7. Wiswash

    Wiswash Active Member

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    Yeah, I saw that thread on generator noise. I think its a good idea to keep a low noise profile, if possible. What would provide better sound insulation than a dozen of those 75# hay bales? except those 75# hay bales are hard to find now. It seems farmers are baling hay in multi-ton rolls
     
  8. ZoomZoom

    ZoomZoom Rookie Prepper

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    We have tons of those square bales around here. Farmers have too many.

    BUT, I sure wouldn't put them near the exhaust of a generator. Sounds like a fire waiting to happen, even with a spark arrestor on the exhaust.
     
  9. sailaway

    sailaway Well-Known Member

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    I have an 8500 watt Elite Gennerator from Tractor Supply, Bought it the day after Hurricane Ike came through Ohio. It was the only one around,( 85 miles away) and does more than I need it to do. It does burn alot of gas though, about a gallon every 2 hours. I am now looking at a 1000 Watt generator at Cabelas, made by a company called Champion. It is $100.00 and only burns 1.2 gallons every 5 hours. (probably made in China and will only run for 1.2 gallons.) My thinking is that it would be nice to have a back up that would burn minimal gasoline and run the bare neccessities in an all out emergency. This particular gennerator is normally about $160.00 not on sale. I have had better luck with Brigs Engines than Honda so I tend to lean toward them. I don't know anything at all about Champion, but have alot of Cabelas points to use.
     
  10. ZoomZoom

    ZoomZoom Rookie Prepper

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    Sailaway,

    I too have redundancy in my generators and base their use on the need at hand. Still haven't figured out if I'll ever need my 225KW but since it burns 11 gallons an hour at no load, I doubt I'll ever use it at the house...

    Let me throw something out for your consideration. Have you considered an inverter and battery setup? I'll run a bigger generator (like your 8.5KW) on-and-off during the day to run the well, septic, hot water, fridges/freezers, cooking... but come the end of the day, I find myself using an inverter instead of a smaller generator. I put the battery in a marine box and strap the inverter to the top of the case. I now have portable, silent power that can run for many hours right inside the house. I run some lights and if it's cold, the blower on the wood stove. Run-time is based on the battery itself but I've had no problems running them all night. The next time I fire up the generator, I just put the battery on the charger and it's then good to go for the next evening. BTW, you would want to use a deep-cycle battery for this application. They're made to be charged/discharged over-and-over with affecting the battery. A regular car battery wouldn't last very long.
     
  11. Wiswash

    Wiswash Active Member

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    Honda is bragging that they make NO BRUSHLESS generators. Reason being that brushless gens do not respond well to changing loads and thus causes equipment damage. Is there a longevity difference in brush vs brushless?
    I always thought brushless lasted longer.
     
  12. Country Living

    Country Living Supporting Member

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    I realize I'm a little late coming to the discussion. I'd like to add my one cent.

    There are a few critical things to think about when purchasing a generator. First and foremost is fuel. Gasoline and diesel may be in short supply and can/will be confiscated by the authorities. A natural gas line could be compromised and fail you when you need it the most. That leaves propane. The majority of reliable propane dealers have numerous geographically separated supplies. They know to fill their large tanks prior to a known event. They have propane-fueled delivery trucks. You need to ask your propane dealer how they operate in case of an event.

    The majority of the portable generators run on gasoline and a few on diesel. This means you have to have a lot of the 5-gallon fuel containers on hand (or larger storage containers) and to remember to keep them full at all times. A run on the gas stations is the first thing that happens in an event.

    The next consideration is the size of the unit. Size does make a difference in more ways than one. It’s pretty easy for a thief to have your portable generator in the car before you even know it’s gone. It’s exponentially more difficult to steal a residential generator. We have a propane powered 16kw whole-house generator with an automatic transfer switch. It seems a lot of the residential generators come with transfer switches that force you to hard-wire what the generator will run in case of a power outage. We didn’t use the switch that came with our unit. We bought a 200 amp automatic transfer switch so we can run anything we choose, within reason (we don’t run the clothes dryer; the stove and on-demand water heater are propane). It’s pretty much life as usual for us when we’re running on generator.

    The biggest benefit of having the automatic transfer switch is the generator stays on until the co-op power is fully restored. This virtually eliminates power surges that can damage appliances. The second biggest benefit is we don’t have to worry about being away from the ranch for several days and losing everything in the fridge or freezer. It takes about 20 seconds from the co-op power going out until the generator comes on.

    A portable or one of the new “quiet” residential generators would be your choice if sound is your primary consideration. The only way I even know our generator is on is the clock on the microwave blinks and the ceiling fans make a little noise (they don’t like dirty power). It’s not that our generator is that quiet - we have a buffer between it and the house. You can hear it running in the other buildings; but, the noise is just not that that intrusive.

    We have two propane tanks. We use one and leave the other full as a part of our disaster preparedness plan. This may be a bit of overkill on our part since our propane dealer will keep the propane running and has guaranteed a fill when we need it regardless of the type of event.

    Portable generators are good for short-term use as long as you have the fuel. We chose not to take the chance. After all, this is about being prepared for whatever comes your way.
     
  13. Wiswash

    Wiswash Active Member

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    Thanks for posting Country Living. it reminded me to come back here and look at the thread. I think its cool that you have 2 propane tanks. great idea.

    I did finally get a portable gen. BCZoom recommended a minimum of 3250 watt so I went the next step higher just to be on the safe side. I got a Honda 5000 watt. Not as quiet as I like, its around 70 db, like a lawn mower, noisy. Weighs in over 200 pounds but has wheels and handles to move it. I had an electrician com out and put in a transfer swith and box for about 350$. Then I did a dry run. At first a couple of the circuits didnt work but then the next day I tried again and every circuit worked like it was supposed to. I have no explaination for why they didnt work at first. My 220 well pump works. Kitchen outlets work. Septic pump works. All the important stuff.

    I built a 4x8 tool shed next to my house inlet so as to protect gen during rain and snow. Duh, I cant run the generator in the rain! I still have to drill a 1 or 2 inch hole in the tool shed for exhaust. Does anyone have any advice on hooking up some kind of exhaust port between the gen and shed wall?

    I went with the Honda mostly because I needed a way to get rid of my motorcycle. And this one dealer was the only one I could find that would work with me on this. This was still a hard trade since he really didnt want my bike. No one is buying motorcycles these days! Even at steep discounts! So I traded my bike for a new generator.

    Thanks for everyones input.
     
  14. Country Living

    Country Living Supporting Member

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    You might want to find some way to secure the generator to the shed.

    Back when we lived in the city there was rampant theft of Harleys for awhile. They were even breaking in garages. I had a local contractor come out and drill out a 6" diameter hole about 6" deep in garage slab - off to the side where it was out of the way. I got huge eye bolts that large chain would go through and cemented them in the hole. We used the hardest chains the local hardware store sells and we got good commercial padlocks from our local locksmith. There was not going to be any "snatch and run" with our bikes.

    Where I'm heading with this is you still need to find some way to secure your generator - as well as your gasoline - even if it is only a time deterrent. Where are you storing your gasoline? Is it in the same shed as the generator? If so, you may want to rethink that when you're running the generator.

    What is the construction material for your shed? One thought is running an extended exhaust pipe through the opening. I'd be a bit concerned about that unless you have someway to "fireproof" - maybe with a thimble of some sort - where the pipe goes through the wall. I'm not an expert on this so wait until someone a lot smarter than me comes along with better ideas.

    On another note: Processes are very important to preparedness. We also have a portable generator. We keep 10 gas containers full at all times (as soon as one is empty it goes in the car to get filled with the next fill up). As soon as we bring a full container back to the ranch, we put gas stabilizer in it. There is nothing more frustrating than not having enough fuel or having bad fuel just when you need it the most.

    If I could impart a little more wisdom on the importance of processes: Be sure to perform annual / scheduled maintenance on your generator. Always keep enough supplies on hand to cover at least two scheduled maintenance cycles. This includes oil, air filters, spark plugs, etc. We keep a case of oil on hand for the portable generator as well as the other equipment that uses that kind of oil. You don't want to be in line at the local auto parts store before, during, or after an event and find out they've sold out of whatever you need because everyone else waited to get their supplies.

    Do your annual maintance on the unit prior to your bad weather cycle. No one wants to be out in the snow / rain / hurricane / tornado weather trying to figure out why the generator won't work.

    Run your generator at least once a month.
     
  15. ZoomZoom

    ZoomZoom Rookie Prepper

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    Congrats on getting your generator and getting it all setup.

    Most car parts stores or muffler shops carry flexible exhaust pipe which should work for you. A reducer may be needed on your generator and a couple set screws should be able to attach it. Make sure you put a collar when it goes through the wall so the pipe doesn't touch anything flammable.

    On you shed, what's available for air intake? You may want to consider a small blower to blow air into the shed for positive pressure. A CO detector may be a good idea as well to assure you're not building up exhaust gasses.
     
  16. Ponce

    Ponce Well-Known Member

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    Have six generators, all gas, from 150W to 5,000W......my favorite one is the 1,000W two strokes.....I live alone so that my needs are very low.....my 5,000 I will start every day for one hour for my frig and freezers.

    One 120W solar panel with two 12V deep cycle batt.