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Home generator size?

Rob01

Rob01

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Minuteman
Jul 9, 2001
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Need a little help from you guys who have portable generators for emergency use. I am looking to buy one for the house. Not looking to fully power the house but just the sump pump in summer, TV some lights and fridge and in winter the oil fired furnace for heat. Been looking around and it seems like a 3500 watt would do it. Anyone have any help for me?

I will say I am not looking to put in any permenant auto system. We don't lose power that much and have city water so no need to pump a well. Just something to take a little of the hardship off.

Thanks in advance.
 
Re: Home generator size?

I would get a little more generator than what you need. A 4500 watt Honda is what I would run. We run several 4500 watt Hondas on our fire engines and they work great, are extremely reliable, and are not obnoxious like the contractor style generators.
 
Re: Home generator size?

Personaly I would go with a top shelf model. A little more wattage than 3500 would do you a little better, it will leave you more flex in what you needed to use. I'm sorry to say but any generator with a Honda motor and power plant will give you great service. I have a DeWalt ind. grade 5500 watt unit.It has a 10 hp honda motor and will start with 1 pull every time. It's not the quietest one out there but I didn't buy it for that. I bought it after Charley hit here in '04 and used it for several weeks while power was being restored.
The one big thing no matter which unit you buy is to run them often,that way when you need it for power it will start.
 
Re: Home generator size?

I run a 5kw here and power a boiler, water well pump, TV and lighting. It works but it's just enough.
 
Re: Home generator size?

Most folks around here have been pleased with the 5500's in the aftermath of Irene.
 
Re: Home generator size?

Other things to consider.
How long will the fuel sit in the tank? Gasoline will go bad quickly. You can treat it with Stabil or other treatment to extend the life of the fuel, but it will still go bad if not used.
Diesel will last considerably longer, but is susceptible to bacterial decay.
Propane will last indefinitely.
The difference in cost depending on the fuel used can be appreciable, with gasoline power being the cheapest.
My 6500 watt generator will run everything in the house EXCEPT
the air conditioner/heat pump, Hot tub, and dryer.
There are automatic systems that will kick in when the power goes out, with only a few seconds interruption, or you can go manual.
Lots to consider, but as is so often said here on the Hide, buy once, cry once. Do the research.
 
Re: Home generator size?

Don't go less then 5kw start ups is where you get killed with electrical stuff.
 
Re: Home generator size?

I bought a 8750W Honda for my house, as well as a switch panel that ties into my main breaker panel. The Generator is enough to run all the 120V circuits in the house and I have a room A/C (window unit kept in the shed) that plugs into a wall circuit.

The Honda is a portable unit and not unwieldy with extension handles and good tires. I roll it to the panel and plug it in, fire up the generator and then throw the DC breakers on. This panel prevents back feeding the utility company's lines and possibly injuring or killing someone repairing the lines!

I have Natural gas so the water is heated and the cloths dryer runs. Not enough ass for the central air or the oven, but we have other means to cook and fans coupled with Room unit for the sleeping area will do fine until the power comes back up.

I ran our house during Hurricanes Francis and Jeanne in '04' when we lost power for 7 days (4 with Francis, 3 with Jeanne).

There's good reason to think about how far you want to go in this as I know of folks who spent upward of 10K on a Guardian System and have never used it! Also, one must consider the possibility of the storm making your house uninhabitable.

My costs:

Generator -$1000
Panel --$300
Labor to install it -$250
I want a Standing room a/c unit but haven't bought one yet. Haven't needed it!

Good luck Rob.
 
Re: Home generator size?

I would go with a min of 5000w, and that might be cutting it close to what you need. As I am sure that you know it is always better to have a little more than to not have nearly enough...

And if power is down for a while it is nice to have a small a/c unit in a bedroom to make it a little more tolerable to sleep at night.
 
Re: Home generator size?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ElCoyote</div><div class="ubbcode-body">Amps x Volts = Watts </div></div>

Big watts sound good, but amps will sap the watts real quick.
We've got an 8000.

 
Re: Home generator size?

rob, look at the honda eu series. I bought one and they're worth ever penny.
 
Re: Home generator size?

Potential brown out on the starting of inductive loads is a factor. All of the major appliances are controlled independantly of one-another so potentially multiple major loads could initiate at once.

Another factor is how your going to plub or connect the generator to your apliances or loads of concern. IR losses (keep it to real power, current * resistance, like was posted) from 30ft+ extension cords is very significant. Peak load at generator will increase (in current and time) to make up for lossy distribution.

If the system is temporary...for example you run the sump when needed, you have load shedding capability and the peak dynamic load is potentially reduced.

Using common generic specs and assumed distribution your looking at 6kW Surge minimum IMO. Given the class-stucture of generators per cost, that's not a big deal.
 
Re: Home generator size?

Just make sure you have a way to disconnect your house from the utilities . Transformers work in reverse as well and you don't want to be responsible for frying some poor utility worker because your back feeding voltage back into the system .
 
Re: Home generator size?

I agree with Lazy, the Honda EU series are the way to go. You can buy a small(er) one and if you need more power later, buy another and run them in parallel. I run the parallel 2K watt versions with auxiliary fuel tanks. An added benefit of buying two smaller versions is that you may use them for other activities since they are so small and quiet.

To determine how much power you need, buy one of these. Don't forget about the surge power to get things started.

http://www.northerntool.com/shop/tools/product_200321255_200321255

Or just use a calculator.

http://www.northerntool.com/catalog/buyersguides/wattage-calculator.htm

One thing to keep in mind is how much fuel you will need.
Most generators quote fuel consumption and run time at half power capacity. The eco-throttle on the EU series is a nice feature that helps keep fuel consumption down.

I would try and get one with a run time of at least 6 hours (so you can get some decent sleep at night). If you cant, make sure it has a fuel pump so you can use and auxiliary fuel tank.

Two is one...
 
Re: Home generator size?

There is much good advice here. A few things to take into consideration are:
How exactly you're going to connect the generator to power the house. There are various ways, some of which are NOT to code.
Are you going to power one side of your panel, or both?
Diesel is far 'efficienter' than gas, as well as the stored fuel definitely does last longer.
Security of the generator. If you need it, so does everyone else.

Good luck on your quest, you're opening a can of "hmmmmm".
 
Re: Home generator size?

Some good info here, and as normal for SH, an about generators,... bullshit as well.

Inrush and a leading or lagging power factor is your biggest issue when dealing with 1 phase 3600 rpm rope start, fly-a-part, unit. Most all big box store units show you the resistive load rating only. They are cheap for a reason.
Fact, when you apply a reactive load to a rope start, the set's electrical rating drops like a rock. Also any area you operate it where the enviro or fuel is not "standard day" or "correct octane numbers" it drops as well. No one whats you to know any of that through.
Buy Generators, like trust worthy glass an sticks, buy once/cry once.

When the sky's clear, there will be lot's of quality an junk units for sale, an many more returned as "Defective".
If your wanting a quality, quite, robust long lasting unit, find a 1800rpm or (lower rated speed) RV unit. Look for names like Onan, Kohler. Another place to find quality is the marine industry. Anything that has a USCG seal will be good quality as well, although it will most likely be water cooled an will require some mods for on shore use. Make sure if you go new or used it is a 60hz unit, lots of military 400hz stuff is getting out there, an some folks are trying to pawn it off as 60.

When it comes to my family's health an safety, money is not the issue. After retiring from the Power Generation Ind, I can tell you this. There is more B/S relating to generators on/off the net, than truth.
KW an quality costs, just like hay, you can buy it before the horse or after it goes threw it, the choice is yours.
 
Re: Home generator size?

Guys thanks for all the info. It looks like I will get a larger generator. I was thinking that was a little small but it looks like closer to a 6500 or 8500 would be better.

I appreciate the help and hopefully it will help some others too.
 
Re: Home generator size?

Rob,
Which ever unit you choose be sure after initial start up you have a way to check output voltage as each generator output can run higher than standard residential voltages. My AO is generally 208 phase to phase. If you try to run a computer or something sensative to voltage fluctuations/spikes you could have a problem...
 
Re: Home generator size?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: queequeg</div><div class="ubbcode-body">Manual Transfer Switches are the easiest safe way to directly wire in a generator to run one's home. This is what I had done.

Here's a link to some options;

http://www.lni.wa.gov/tradeslicensing/electrical/files/currents/elc0706.pdf</div></div>

+1

You can purchase a manual transfer switch from home depot and they are very easy to install.
 
Re: Home generator size?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Guys thanks for all the info. It looks like I will get a larger generator. I was thinking that was a little small but it looks like closer to a 6500 or 8500 would be better.

I appreciate the help and hopefully it will help some others too. </div></div>

Are you planning to use natural gas for fuel? I just ask because generators of that size will burn about a gallon of fuel and hour. During IKE, our power was out for over two weeks and getting fuel was not easy during the first week.
 
Re: Home generator size?

I use a 5500W with 8500Surge. I backfeed through the welder plug in my garage and have a manual disconnect in the basement to not cause any backfeed issues to the lines. I runs everything in the house except the garage heat (electric) the heat pump or central air. It runs both fridges, a freezer, lights, TVs, sump pump.. just about anything I want. I have a Yamaha ev3000 also. Super quiet and runs a long time on a tank of fuel.

keep in mind the load on the generator will effect the fuel consumption. Get one with at least a 5 gallon tank.
 
Re: Home generator size?

Rob,

I have a 5550 (running/8500 starting) generator. I have it wired into a 6-circuit panel of which only five will be used at a time: summertime will run the sump pump, winter the furnace. It's a little overkill for my needs, but always better to have a little too much than not enough. It's rare I lose power, but once was during a harsh winter...never again.
 
Re: Home generator size?

Well I got a Husky 5000W unit at a local home depot for $539. Got really good reviews on their site and I know 4 people with them. I do plan on hooking up a manual transfer switch as well. Will make life easier. Thanks again for all the comments and suggestions.
 
Re: Home generator size?

That is a good choice. If you are just running the sump pump and some incidentals you will be fine. After Katrina I did fine with a 5500w. I ran it for an hour three times a day and only had 3/4 load at any one time. I would plug in or turn on in sequence so as not to surge the generator.
When we built I went with a 40kw automatic set on natural gas. It has really come in handy. It looks like we will need it again this weekend.
 
Re: Home generator size?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lazy21</div><div class="ubbcode-body">rob, look at the honda eu series. I bought one and they're worth ever penny. </div></div>

+1
 
Re: Home generator size?

With generators be mindful that to gain the best out of them they like to run near to full capacity to be the most efficient.
I would work out what you would like to run and match the genset to that load.
Being mainly used for emergency use and running only essential appliances you could get away with a smaller unit.2.5-3kW
However to run the majority of your house as stated 5-7kW would be the minimum. I would avoid the use of high draw start up appliances, pretty much anything with an element.
Having used a few systems I would rate the honda units as being the best with regards to small portable units otherwise something like the fg wilsons for a fixed one.
When connecting to the house make sure you use a switch that is run in parallel with the main switch and parallel'd from the load side that way you can isolate the normal main switch from the grid and then use the genset switch as the main switch.
 
Re: Home generator size?

You should run your generator once a month for at least 15 minutes with a load on it. The generator can go bad if it just sits for months on end.
 
Re: Home generator size?

Rob,

Congratulations! You have your genset.
I have a Honda 6.5KW and have "been down the road". I use it for house back-up, remote site power, and powering my Miller 251 mig for portable use.

Some Tips:
o Set up a transfer system.
o This unit is probably a 250v only w/ 125v taps. Since you will be powering 125v devices, get a clamp-on ammeter (unless the transfer has one) so that you can monitor the "legs" to maintain load balance on the generator.
o Always use StaBil in your fuel.
o Drain the carb after every use. Drain the fuel tank periodiclly or after every use (preferably).
o Use a good quality synthetic oil in the engine.
o Conduct a periodic load run. (In telecom, we required weekly starts, monthy 1hr, and annual 8hr runs.) The main thing is to ensure "it works when you need it".

Kevin
 
Re: Home generator size?

Thanks for the advice. Definitely plan on using stabil, actually bought a big bottle the other day for that and my Galaxie, and getting a transfer switch so the wife can just plug in, flip switches and get power and heat when I am at work.

I will start it periodically also. What do you recommend running off it to put it under load?
 
Re: Home generator size?

Rob,

There are commercial load boxes available, but can be expensive. Use the transfer and run what you would be protecting in the house. If that is not feasible (ie fridge or sump pump not running), use some high-wattage (500-1000 w) security/work lamps for the load. I have a couple 1500w and eight 500w work lamps if I need to do a "test run".

Kevin
 
Re: Home generator size?

Cool. Thanks Kevin.
 
Re: Home generator size?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Thanks for the advice. Definitely plan on using stabil, actually bought a big bottle the other day for that and my Galaxie, and getting a transfer switch so the wife can just plug in, flip switches and get power and heat when I am at work.

I will start it periodically also. What do you recommend running off it to put it under load? </div></div>

Run a battery charger on it. That will be a decent draw.
 
Re: Home generator size?

I've got 6200 and 5500 watt generators and can hook either one of them to the house transfer switch. Currently I only have the switch feeding eight circuits but am planning to go whole house minus 220 this fall. This requires coservative use of the points of draw. I'm also setting up another switch for my shop that's on a separate panel.

I use an old 1/2 hp electric leaf blower that a guy gave me for excercising the generatorws. I only put a 1/2 gal of fuel in both my gennies at a time and run them about a half hour every two or three weeks for 20-30 min at a time. I turn the fuel valve off and let them shut down on their own.

I've been using Stabil but I'm gonna switch to Sea Foam to help with water issues. I store about 30 gallons of high test and don't keep it any longer than a year. As I use a 5 gal can up I go refill it and keep the newer gas separated.

At the next oil change I'm switching to synth oil also. Heard very good things about it.
 
Re: Home generator size?

If you are planning to get a larger generator, you may want to look into Lincoln or Miller engine driven welders, they hold lots of fuel, 12kw output, and you end up with a portable welder that you might use more than just a generator. I just did not want to dump the money in a generator that I would really not use very much, but the welder gets used all the time.
 
Re: Home generator size?

here's my suggestion. food plot tractor ebay transfer and your good to go.


346935510_photobucket_1452_.jpg
 
Re: Home generator size?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: procovert45</div><div class="ubbcode-body">here's my suggestion. food plot tractor ebay transfer and your good to go.


346935510_photobucket_1452_.jpg
</div></div>

For the win on this one.

I was going to suggest getting a nice 10Kw Genset with 100gal propane tank and have it permanately installed. Burning 10-20k right now may seem tarded but when the time comes you'll thank yourself. It most likely will not be enough to run your whole house but it will be enough to keep the heat on and food warm. I have done a few genset installs here in the states on houses and plan on doing one on my own home after the next trip over. I have installed a shit ton of gensets overseas and have lived for years off nothing but gen power. Things get a bit more complicated when running full time.

Another option you may consider is Solar and Wind. Even during the winter time the sun is shining most days and wind is blowing. I have a friend from WI who lives completely off the grid using Solar and Wind. House size is 2000sf and has the option of electric or fire stove for heat. Again its quite the investment but you can backfeed unused power to the grid and get them to pay you. I also think you can get some kinda tax cut or rebate for going green as they call it.

I have a system setup at my FIL's house that he can plug in his small portable genset he uses on his RV at the deer camp if power goes out. Was a simple plug, breaker, and transfer switch with a cable built to link the two.
 
Re: Home generator size?

rob,

i can help if you'd like. i used to sell gen sets from 12KW to 3.25MW...

for what you describe, there are some real easy ways to do this.

the best would include a transfer switch on your home, but you don't have to go to the expense of doing it that way if you don't want.

for example, you could buy a 'subpanel' and move the breakers out of your main panel into the small subpanel... you feed the subpanel with a 40amp (depends on gen set size and what you want to run) 240 VAC breaker. this panel is wired to an external socket on the side of your house.

you experience a power loss. find your main panel and shut off the breaker (the 40amp one from above) that feeds your subpanel. the circuit is now open and isolated from your main panel. fire your little set up, plug the set into your exterior plug in and now your subpanel and the circuits you have in it are being run by the gen set. the other cool thing is that the minute you regain power the balance of your home (still unchanged in your main panel) starts up and you know you're gtg. then just reverse the order of start up on your gen set and you'll be golden...

something in the 6KW to 12KW will work like a champ for you. pumps require a bit extra power upon starting but then taper off quickly. same is for your fridge and freezer compressors. blower fans on a forced air furnace would be the same. some folks simply rotate each of those i listed above by turning the breakers for these circuits on for an hour or so, then back off so another appliance can run for a while. that usually will do fine if you aren't trying to watch a movie inside of your fridge (door open joke i lay on my wife periodically since she likes to stand there and stare at the fridge contents routinely)... just leave the stuff like pump on all the time and possibly any 120VAC smoke/CO alarms you may have on full time.

i might be able to find you a source or two for a nice set. <span style="text-decoration: line-through">those cheap pieces of shit from home depot are worth skipping.</span> ((<--- woops, didn't see that you already bought one. my bad.)) the premise of a back up gen set is to operate when nothing else will. thus, if you go cheap you'll regret it.

motor choice and maker are big differences as well as the muffler... i wouldn't sound like it, but a nice muffling package is worth it. so look at the decibel rating of the running unit under load. they aren't created equally...

if you haven't picked anything up by the time you come to my place at the end of the month we can discuss it. hope this helps.

-michael
 
Re: Home generator size?

I work on generators as a hobby. I buy used Onan and Kohler generators and return them to service. You would be amazed at how many high end generators simply don't get used, or exercised, and fail to start when called to duty. I wouldn't own a generator sold at retail outlet other than a generator made by Honda and fueled by LP or NG. The gasoline made today is not friendly to carbs and doesn't store well at all.

I use a 10kw Kohler (powered by Kubota diesel) to run my whole house. I have diesel car, tractor and mower so the fuel makes sense for me. I can power my well, furnace, A/C, lights and entertainment no problem. Heating and cooking appliances are propane fueled.
 
Re: Home generator size?

For what you want a 5500 ot 8500 watt should fit the bill nicely. My power goes out quite often and I purchased a Troybuilt 8500 watt. I just turn the main breaker off and plug this into a 240 volt outlet with a neutral to backfeed my electrical panel. It is enough to power my water heater, microwave, a burner on the stove, tv, fan, and 2 refridgerators. I would also strongly recommend something with an electric start. They cost a little more, but well worth it. Some even come with a float charger to ensure the battery stays charged up when needed.
 
Re: Home generator size?

We actually lose power a lot. Ice Storms, wind storms, thunderstorms and lightning strikes all knock out our streets power. We live out in the country and I wanted to make sure my wife and kids were warm in the winter and cool in the summer months. I went over board but I did a 10,000 watt propane fueled generator. Its mounted to a concrete block about 15ft from our in ground propane tank. Since almost everything we have runs off propane I thought the generator was a no brainer when I saw it was offered to run on something we already have.
 
Re: Home generator size?

Good info guys. Since I bought my house 11 years ago I can count on one hand the times I lost power for more than a couple of hours so a big, expensive generator wasn't what I was looking for but hopefully the info helps others here.
 
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