Generator Thoughts?

[sixty4]

Hi all. Getting the final plans together for the new garage build. I want to do a standby generator for the house and the new detached garage. After talking with a local generator company they determined that a 30kw propane standby will do the job. The person who came out mentioned that I should purchase one that spins at 1800rpms for noise. I agree with this as my old portable spins at 3600 and can wake the dead! Ok the questions are the following:

What Brand standby generator?

Also for those that have done this the beat place to purchase from?

Thanks for any help!

 

[Sundowner]

30kW?!? That's f'ing nuts.
are you planning on welding together five running room air conditioners in a blackout?

You are going to either a need a huge dedicated gas line from the street or one big-**** tank in the yard to feed that monster, and that's gonna COST in install and when the gas bill arrives.

My house has a Generac automatic standby generator that is 7.5kW and it powers pretty much everything of merit in the house from the fridge to the cable TV box. I even have it hooked up to the ouside lights so I can show off to the neighbors when the rest of the street goes dark.

more is not always more. a huge generator with a light load will gunk up faster and not live as long as one that operates at it's designed 60%-80% load.

 

[russlaferrera]

I'm with Sundowner on this. It's a BACK-UP generator for an emergency. My portable 5500w runs 2 freezers 2 refrigerators house lights and my well pump.

Granted I can not run my heat pump, or arc welder, or make any hot water, but the basics are there.

IMO power outages for days are rare. Can you justify the bigger unit?

 

[Tscott]

Sixty4,
What size home do you have? What do you plan to run off the generator? Sounds to me like the local generator company works off commission and/or they have a glut of 30KW units in stock.

Depending on your utility, you may only have a 15KV or 25KV transformer serving your home. (1KVA = 1KW for the most part. there is a power factor involved but in this case it is probably negligible). If your home has a 200 amp panel, chances are you will never see more than 50 amps or so through it at any one time even with an AC running. The only exception to this is the starting amperage of the AC, LRA (lock rotor amps) on a 4 ton for example can be around 118 amps, but this is for a a short period only while the pump is spooling up. Generators have a separate rating for these high amperage short duration loads.

You need to go through the available loads at your home and really decide what you will need. If you decide you want to run everything, then you can use a load diversity factor. This means that not everything will run all at once. So you can't just add up all the loads. Lights are usually constant, however not all will be on at the same time unless you like that sort of thing. Kitchen equipment is high draw, but is only used a few times a day and during those times you could shut off things like AC or Heat. Water heater can be switched on and off at the breaker and hour before shower time. AC or Heat can be run when all you are doing is watching TV or on the computer.

If you do the math and 30KW is what you need then good luck, and best wishes. However, I would suspect that you are probably more suited for a little smaller generator.

Here at the utility, we can push a transformer past its rating for a few hours with no problems, but generators tend to die in those situations, so being a little conservative is OK, but 30KW seems pretty big. However it will definitely allow you to carry on comfortably in the event of a storm. Hell you could be the most popular guy on the block. I can just see it now, welding party and hair dryer fight next time the power goes out.

Tom

 

[79firebird]

Dam that thing will be huge i was looking at a 30kw one online and they are huge and you will need a huge tank for it looks like ittle burn 6.11 gal/hr. @ full load. Also looks like they put out 150-200 amps depending on brand. I think you should beable to get away with a 15kw one inless you will be running compressors, mig welders, plasma cutters and every thing in the house well the power is out

 

[thammel]

I agree with the guys above on a smaller unit doing the job. I have a 3000ft^2 house with a 220v/200 amp main panel and I bought a Dyna Winco 8kw unit that runs on propane or NG. I run off propane. I did all the installation except I had the propane people connect me up to the propane supply (cost about $250). The generator and ASCO super heavy suty transfer switch cost $3150 2 years ago. I did all the installation myself (pad and wiring). It powers a well pump, propane gas furnace, all the freezers and refrigerators (5 of them!) and all the lights, tv and everything we need to be self sufficient. No, it does not run the a/c. Yes, it spins at 3600 rpm and is noisy if you're next to it. I live on 1.3 acre lot. I have the gen at the end of the house away from my master bedroom and you can not hear it there. Inside the house it's barely noticeable.

I recommend buying a transfer switch as I did which does not limit the number of circuits the generator runs. The big Asco unit simply switches power from the untility or generator and then feeds this out to a subpanel you install. The subpanel normally has utility power fed to it and this is distributed to all the circuits on that subpanel (you can put a subpanel with 20 spots or more on it!). Then when the generator is called into service, this subpanel is fed generator power. Clearly, you don't want more circuits on there than your generator can handle but it allows you more flexibility than the Generac approach.

Tom

 

[must8657]

I just bought this one http://www.norwall.com/product_info.php?products_id
=639&osCsid=11ab16f488dbcd58d7ee5da09d95e405

It is 20k watts and with the switch i can handle up to two AC units (it will only power on one at a time) . When i called them to ask why this was cheaper but with longer warranty than the others, they said they were being made specifically for a big box store (lowes, hd...) and the chain had then backed out.

One thing i would suggest from my research is to buy a switch that goes between your meter and main panel (basically a whole house switch). Less wiring and you don't have to decide ahead of time what circuits you want to protect. Also, if you haven't already installed a main panel, one of gen companies and i think square d now have a main panel that includes the circuitry for the standby gen.

 

[Junkman]

I had a 28 KW Kohler generator, and it had a 6 cylinder Ford Industrial engine to power it. I bought it from a Bradley's store that had closed, but after researching the fuel consumption, I decided that it wasn't practical for my home. I sold it right before Y2K at a good profit. It had a hospital quiet muffler that was about 15" in diameter, and 5' long. There is no way that I could realistically use a generator that was designed to fully power a 30,000 square foot store to power my 3000 square foot home. I have a 8 KW propane Winco generator installed that screams at 3600 RPM that I never use. If I were to buy another generator, I would only consider using a 1800 RPM water cooled diesel unit at this point. I have researched them extensively, and have come to the conclusion that the inexpensive units are not worth buying unless you don't think that you will need it very often. Most are not designed for long term use, such as a major power outage during a hurricane that takes out large areas of service. Diesel powered water cooled generators are not cheap, but the are long lasting. You get what you pay for.

 

[sixty4]

I have, a 5000 sq ft house. 1) 5 ton ac unit that does the main house. Now when speaking with the generator co. I had mentioned that only the vitals were important. AC in summer, Heat in winter (propane fired hot air furnace. Hot water heater is propane and is direct vent so I need this to run. Here is the other things we need, kitchen microwave, stove and a few lights. I would like to have a circuit for the master bath and master bedroom. No sump pump or well pump. The garage doors have liftmasters with battery backups. Seems like a **** load for size as well to me but, I am not sure? I realize you won't run the heat and ac at the same time. He says the ac Compressors will kill me at start up more than anything? I have a 1000gal propane tank.
HELP!

 

[79firebird]

After talking to my buddy down the road he does ac and heating for a liveing and looking on the web a standred 5 ton ac even the old ones pull MAX 12kw on start up. So im thinking a 15kw would be much better for your needs. Also for most ac units you can get a Kickstart hardstart device wich will make it easyer to start on a generator. so you would be fine with a 15 inless you are running the ac, stove,dryer,micro and what not wich would put you over 15 i think. there are online manuals that show you what wattage stuff takes. or is your stove and dryer on propane also?
here is an avrage on propane usage on a fuee diff generators and sizes

Remember that LP tanks are rated in gallons of water capacity. The LP tanks fill is 80% of this figure, so a 250 gallon tank holds only 200 gallons. The chart below gives you some idea of the fuel consumption at 50% load and 100% load. You can expect your generator to average 50% load fuel consumption when properly designed. We recommend having 10 days of fuel storage and at least 4 days as a minimum.

Gillette 12 kW uses 2.3 gallons per hour at 100% load and 1.04 gallons per hour at 50% load - 7 day operation = 174 gallons
Gillette 16 kW uses 3.4 gallons per hour at 100% load and 1.64 gallons per hour at 50% load - 7 day operation = 275 gallons
Briggs & Stratton 7 kW uses .90 gallons per hour at 50% load - 7 day operation = 152 gallons
Briggs & Stratton 10 kW uses .94 gallons per hour at 50% load - 7 day operation = 158 gallons
Briggs & Stratton 12 kW uses 1.13 gallons per hour at 50 % load -7 day operation = 190 gallons
Briggs & Stratton 15 kW uses 1.36 gallons per hour at 50% load -7 day operation = 229 gallons
ONAN 20 kW uses 3.18 gallons per hour at 100% load and 2.00 gallons per hour at 50% load- 7 day operation = 336 gallons
ONAN 30 kW uses 4.0 gallons per hour at 100% load and 2.52 gallons per hour at 50% load - 7 day operation = 423 gallons

hope this helps. =)

 

[sixty4]

Thank you! Yes it does......

 

[wilbilt]

Holy cow 30Kw? For a house?

Our local hospital has a 40Kw generator. They have to calculate for essential loads. I don't think A/C and heat count as "essential".

 

[79firebird]

wilbilt they might have more then 1 generator and also chances are its a 3phase wich you can run more off of. instead of 2 hot lines it has 3. the local hospital 10 min from me has 2 generators that are huge like the size of a semi tractor traliler. If i reamber right there around 100kw each small compared to some. the local home depot has a 80 its self

 

[Stuart in MN]

There are a number of online generator sizing guides and calculators out there, here's a couple: https://www.ch.cutler-hammer.com/generatorCalc/wattshow.jsp http://www.generatorjoe.net/store.asp Do a google search on 'generator sizing' to find others. Generally, if you have a large load (like your air conditioner) to deal with, other small loads like lights, computers, small appliances are almost inconsequential when sizing the generator - the main thing is making sure it's big enough to start that big load.

Another thing to consider is if the motor has a soft start or variable frequency drive, the starting load is much less and you can get by with a smaller generator - I don't know for sure if air conditioning units come with those, but they aren't uncommon on modern furnaces.

 

[Tscott]

wilbilt they might have more then 1 generator and also chances are its a 3phase wich you can run more off of. instead of 2 hot lines it has 3. the local hospital 10 min from me has 2 generators that are huge like the size of a semi tractor traliler. If i reamber right there around 100kw each small compared to some. the local home depot has a 80 its self

40KW is 40 KW whether its 3Ø or 1Ø. It just means that the 40KW of capacity is devided evenly between the available windings in the generator.

And as for the OP. Call your AC guy and ask him to get you information on a hard start kit for you AC. This may reduce your starting current enough to allow a smaller generator. It sounds like they sized the 30KW off the starting draw of your AC unit. If the LRA is too high then you will cause a low voltage condition to other accessories in the house when the AC compressor turns on, which could kill things like computers and TV sets.

Good luck,
Tom

 

[Gummi Bear]

If you want a 30 KW unit, go look at 30 KW units. 30KW at 240V single phase, is 125A of standby power.

Fuel consumption (get your local electrician, or generator contractor to explain these to you, I'm short of time for a lengthy description):

Diesel : .085 x KW = Gal/Hr
Nat Gas : 950BTU / ft3
LPG : 2515 BTU / ft3



It's gonna be spendy, don't kid yourself.

Look at Kohler, Onan (Cummins), Waukesha Pearce and Generac. Caterpillar makes a fabulous product, but it's crazy expensive comparatively so. I don't even price Cat until I'm looking for one that's 1meg (1 million watt, or 1000KW) or larger.

 

[Stuart in MN]

Look at Kohler, Onan (Cummins), Waukesha Pearce and Generac. Caterpillar makes a fabulous product, but it's crazy expensive comparatively so. I don't even price Cat until I'm looking for one that's 1meg (1 million watt, or 1000KW) or larger.

I spec out generators all the time (I'm an electrical engineer), mainly in the 50-500kw range. It may depend on the local dealer, but around here Cat is generally very competitive in price with the other guys. They do have a line of smaller generators called Olympian that covers the residential market.

They did get caught out on the latest emissions requirements for diesel generators so they do have some holes in their lineup at certain sizes where they haven't gotten their units certified yet.

 

[danski0224]

Hi all. Getting the final plans together for the new garage build. I want to do a standby generator for the house and the new detached garage. After talking with a local generator company they determined that a 30kw propane standby will do the job. The person who came out mentioned that I should purchase one that spins at 1800rpms for noise. I agree with this as my old portable spins at 3600 and can wake the dead! Ok the questions are the following:

What Brand standby generator?

Also for those that have done this the beat place to purchase from?

Thanks for any help!

You need to take a class to learn the difference between "essential" and "non-essential"....

30kw? You are kidding, right?

Whan I was in the service, a whole lot of people could plug into a 30kW genset... and it was big... and thirsty... quiet, though

Hell, maybe you have money to burn, so have fun with that.

I will make due with my little 3kW Honda inverter... it will run all day on a few gallons of gas.

 

[sixty4]

You need to take a class to learn the difference between "essential" and "non-essential"....

30kw? You are kidding, right?

Whan I was in the service, a whole lot of people could plug into a 30kW genset... and it was big... and thirsty... quiet, though

Hell, maybe you have money to burn, so have fun with that.

I will make due with my little 3kW Honda inverter... it will run all day on a few gallons of gas.

Just purchased this:

http://www.electricgeneratorsdirect.com/Guardian-QuietSource-5640/p1834.html

 

[Junkman]

LP Consumption (50% Load) 3.0 gallons/hr

Propane is about $3.50 a gallon, so I hope that you can afford to run this monster. If I were going to spend that kind of money, I would have gone for a diesel that will use less than 1/2 gallon an hour at 100%, and will outlast your engine about 10 years to propane's one year. Wait till you find out what size tank that you are going to need to keep that going. My guess it is going to look more like a tank truck than a propane tank. Then consider how much it is going to cost to fill a 500 gallon tank with propane, and the diesel will look much more affordable. The only good thing that I can say about propane is that it burns clean and doesn't go stale... but so does diesel last a very long time... Junk.

 

[sixty4]

I pay 2.89 per gallon.... Its only money, I will make more........

 

[madjack]

my motorhome has a 6500w onan that is very quiet and it powers 2 a/c unit or 2 electric heaters along with all the rest of the standard gear. I have a 6500w Honda for my home in the mountains and had no trouble running all the esentials last winter for 5 days without power due to a monster snow storm. Used about 7 gal. of gas per day, with a 50 gal. back up tank on hand. The Honda is so quiet you forget it's running.
I understand about the propane, The larger units are more trouble free if run on propane or natural gas. but the cost of the switch gear is prohibitive

 

[Havepower]

Disasters, Hurricanes, Wind Storms, We’ve seen the after-effects, entire communities without power!

Here are some tips on how to safely restore power due to unexpected power outages and safely use emergency generators.

How to Choose the Right Emergency Electric Generator
http://www.mainpowerconnect.com/static3/howto.asp

How to Safely Operate a Portable Generator and Transfer Switch
http://www.mainpowerconnect.com/static3/index.asp

Generator Safety Frequently Asked Questions
http://www.mainpowerconnect.com/static3/faq.asp

 

[Ira]

I bought this one...

http://www.electricgeneratorsdirect.com/Guardian-QuietSource-5638/p1832.html

...from my local Guardian dealer about two months ago. 22kW (40kW surge), liquid cooled, 1800 rpm, 2.4L Mitsubishi 4 cylinder, LPG fueled. I paid quite a bit less than the price shown on the website, but I'm sure my dealer made up for it on the installation cost.

My area was hit by Ike. Fortunately, I was on the "clean side" of the storm, but we lost power for four days. The town eight miles south of me had widespread power outages for over two weeks.

The generator powered a 17 year old four ton A/C (i.e., not very efficient), 1.5hp water well pump, two refrigerators, washer, gas dryer, and everything else with no problems at all. I have half a dozen UPS's running various computers, DVR's, etc., and I only heard them beep once or twice during the four days. I have a "whole house" automatic transfer switch, so everything had power. The only thing we didn't use was the electric oven. My dryer, cooktop, water heater, and furnace are LPG.

This model uses the same engine as their 27kW model and th OP's 35kW model, so I am confident the engine has plenty of power. There were several times when the well pump kicked on while the A/C was running and vice versa. The odds of both kicking on at the same time and overloading the surge capacity (even if it would) is so small it wasn't worth worrying about. Remember that the surge for either lasts well less than a second.

I run it off of a 500 gallon propane tank. The generator probably runs at 25% load except when the A/C is on. I figure I can go a week without refilling the tank.

IMHO, if this model proves to be reliable, Guardian/Generac has a real winner in its lineup. This thing should easily power everything in a home with up to 5 tons of A/C. Most of the competition is at least at 25kW, and many start at 30kW, and they are substantially more expensive. Plus, Guardian/Generac seems to have the best dealer network set up for residential installations.

The funny thing is many of my neighbors wanted to know more about it while the power was off, and said they wanted to talk to me about it once everything got back to normal. Four weeks later, no one has mentioned it. Guess they won't until the next time.

 

[NicksTrix]

yanmar 4 cyl diesel wiht 17.5 kw head. power whole house, all electric.
it's been a great investment.