I just installed a power generator this summer. I read a lot of posts on this forum before I made my decision.

What are good brands?
Kohler, Cummins Onan. Kohler is a little cheaper than Onan, Onan is a little better than Kohler. Both very good,

How large a unit will we need?
You need to get the specs for all the items you listed and add up the amps.

What will maintenance costs be?

Could be as low as 25 bucks per year if you buy the right unit and know how to change oil and air filters. Don't chince on the unit - you get what you pay for.

What's the normal lifespan of a generator? That is a tough one to answer - a lot depends on usage. My generator requires a major maintenance at 500 hours of use. I expect to use it about 50 hours per year. That is 10 years before I need to either put some money into it or buy a new one. That doesn't mean the unit will be dead after 500 hours - just a key decision point.

What noise level is there from a gas generator?
It is quiet - no louder than a gas lawn mower running. Juts don't put the thing below the master bedroom window if you can avoid it.

How large are these things? ( general dimensions)
The concrete pad i made was 4 feet wide by 6.5 feet long. The unit I bought (Kohler 12RES) is about 30 inches wide by 48 inches long and about 40 inches high. Weighs 400 pounds. Just rough numbers.

For how long a period can one be in use?
There isn't a spec on that. I know someone who ran their Kohler for 3 straight days with no issues. If you are in a very long outage, i would rest it periodically and check the oil level to make sure it is full.

Any other considerations? Check out Ziller Electric on line. I believe they are located near your area - they sell Koler and other genny's. Great prices and very helpful.

Do not buy a genny from Home Depot or Lowe's. read up on that here on the forum - big mistake if you go that route.

Good luck.

When a generator technician or salesman says "gas", that is natural gas or propane. "Gasoline" means just what it says. Gasoline is nearly obsolete for standby sets, your choices will be gas or diesel fueled units. For residential, non-critical use gas will nearly always be the recommended fuel. Diesels cost more and are rarely seen in residential use.

Any good generator vendor will answer all of your listed questions for free. If you have difficulty getting help before the sale, there is a good chance that you will have similar trouble afterwards-move on to a more supportive vendor. There are 3 major players in the size range you will probably buy-Onan, Kohler and Generac.

Bigger and/or higher quality generators cost more; you get what you pay for.

Winco is another quality brand.

Stay AWAY from "Guardian", even though they are made by Generac.

Another consideration - if you buy a Kohler generator make sure you get the carburetor heater and the battery heater accessories. You will need them in your climate zone.

The Kohler units come configured for natural gas but can very easily be converted to Liquid Propane (LP) which is what I have. All the parts for the conversion come with the unit and it takes about 5 minutes to make the change.

We have a 15KW Guardian by Generac. It is now 4 years old. Up until Ike, its run times had been limited to about an hour or so. Then Ike hit Houston and our neighborhood was without power for 12 days. Other than a once a day planned shutdown so I could check/top up the oil, the unit ran 24/7 for those 12 days. Powered our whole house including central ac, cooking laundry etc. Enabled us to maintain a pretty normal standard of living while the surrounding area suffered greatly.

The Generac was less than half the cost of its nearest competition from Onan or Kohler. THe Onan and Kohler units are built better and should last longer. They might also be quiter. But our Generac works great, service has been limited to one battery replacement and an annual oil/filter change with synthetic Rotella oil.

The unit consumed less than 1 gallon of oil during Ike, starts and runs for 10 minutes every Sunday morning like clockwork. I would not hesitate to buy one again. It is not a prime power unit, its built specific for the home standby market but functions great in its intended application.

LP = Liquid Petroleum, but it is a synonym for propane.

Make that "LiquiFIED Petroleum" gas.

Many thanks to all. I'm feeling more confident that I can read bids with some understanding. Will probably be back for more help after bids!

The electrical engineer that my architect used for my house wasn't the sharpest tack. Rather than designing what I had originally asked for (to split the essential loads on their own subpanel), he just put in two subpanels willy-nilly and sized the generator to power the whole house. The size of main disconnect between the meter and the generator transfer switch looks like it could disconnect the whole neighborhood. At least it makes a resounding clack when I throw it (which should be fine when the generator is hooked up and kicks in shortly there after).

Hi,

Yes we went through the same difficulties as you. 5 days without power, and after that due to ice a broken HVAC system due to burst pipes. So about two years ago we installed a generator.

My data is a little old, but I think still valid-ish. I have posted in the past on this topic, but in general we can class generators into three broad catagories:

1) Petrol / gasoline powered. 3kw to 7kw, Portable. $US 700-4000. Best in class is the Honda EU6500ISA. Inverter technology, means it is more economical to run and uses less petrol. Advantages of this class is cost. Disadvantages are you need to be around to run these, and you need to have an able bodies person to move the generator around, start it up, refill with petrol. Go and get more petrol every 24 hours or so. Max petrol storage in most residential areas is 20 gallons. This lasts maybe 24 hours of generator run time. Install costs for a transfer switch $US 200-1000. Gasoline can only be stored for about a year with stablizers before it goes off. Size of a large lawn mower.

2) Natural gas via mains feed / propane in a tank. Not portable. 5kw to 15kw. No concrete pad install required. $US 2400 - $US 7000 + install costs of $US 1000 to 2000. Advantages, auto start, no need to wheel it out. Propane can be stored indefinately. Most popular route for most people. Lawn mower based engines, running at 3,600 rpm. Size of garden tractor

3) Natural gas / propane tank. Car / truck engine. Water cooled. $US 9000 and up. 15k to 45kw and up. Costs $US 10,000 and up. Heavy, crane / hydrolift equipment to install. Concrete pad required. Size about two car engine compartments. Weight lbs 1200. Install costs $US 5000 and up. Runs at 1,800 rpm.

In the end we went for option three. A Cummins Onan RS 20,000, 20kw. Ford car engine based (For Ranger Engine converted for Propane). Bought from Costco. Installed by local electrician. Total bill of about $US 20,000. Required a small hydralic lift. Lots of digging and rewiring. Very reliable, now on third year, no issues. Instalation of a 500 gallon propane tank. Total project took about 2 months from order, install to passing local code inspection.

We rewired so that our 400 amps supply, is split into two 200 amp sub panels. Only one sub panel is backed up by the generator. Our priorities are:

1) Well water pump
2) (For you sump pumps) we have no sump pumps but have a ejector pump
3) Oil fire furnace electronics and blower
4) Air handlers for heating x 2.
5) Fridge
6) lights
Here on out are optional
8) Kitchen power
9) Gararge doors
10) Air conditioning. This is a major power hog especially at start up.
11) TV
12) Microwave

Not backed up are electric oven and electric dryer. Too much power required.

A good measure of generator quality is weight. The heavier it is the better. Why? More copper in the windings, more steel in the engine. Better chunkier housing. Lower RPM is also good, less wear and noise. Water cooled is better.

Good luck.

All the best, Mike.

Mike, Thank you for all the detail on comps and the tip about weight and RPM's. Very helpful.

We had a quote (including installation) a few years ago but I can't find the paperwork. It was around $10K. I don't recall the make of the generator.

I expect we'll move ahead with this after the holidays. One company has come in to look. Another hasn't returned phone call. Still looking for a 'third'.

Chisue, thanks for starting a great thread.

This is a bit tangential, but I'd like to throw it in anyway because it has greatly simplified our efforts to figure out how many kw we want out of our generator. It's a power cost monitor. It is always transmitting our real-time power usage to a small unit that we keep where the kids can see it. We got it on the cheap with a rebate from our electric company; perhaps you can too.

Anyway, when we wanted to figure how how powerful a generator to get, we simply turned on the appliances we needed to use simultaneously, making sure, of course, that the compressor for our fridge and the power vent for our boiler were running as well, and looked at the reading on the monitor. The monitor can display usage in kw as well as dollars. We then padded that number a bit, and we'll still sit down, go through appliances, and double-check the numbers, but it was so easy to just turn things on and watch the meter.

It's also been a GREAT tool to get the kids to remember to turn off the lights, and to get the adults to switch to more efficient bulbs. We've recouped our unit cost ten times over in terms of modified consumption, which of course is why the power company subsidized its cost. They'll do anything to avoid having to build another plant.

Here is a link that might be useful: Power cost monitor information

I have been looking into the energy monitors. The problem with that one is no computer interface, although the cute idea of watching the meter wheel spin is neat.

There are some out there that are current transformers that you can install around your mains and that I will probably do.

Hi Chisue,

Glad you found the info useful. The $US 10,000 bid las time round I think puts you into the class two gen set area. These are good systems and popular where I live. Auto start and essentially auto everything. Good in that when the power goes out you do nothing and everything comes back on line in about 20 seconds.

These units are lawn mower engine based. Typically air cooled and have two cylinders. They run fast at 3,600 rpm and are noisy. But this is not that big a deal in that this is for only a few days of running untill the power comes back on.

The amount of power they can handle is about 10-12kw range. Some companies rate them higher like 15 kw, but I would say this is pushing it.

Another something worth remembering is starting current. The other poster was correct in that the calculation is amount of power + some buffer. The some buffer is important. The reason why is that at start up, electric motors draw a lot more current. Can be up to 8 times as much. So to handle this surge you need a big generator head, more copper, and a heavier momentum in the engine. You can begin to see why heavier is better in generators.

You have two sumps, I do not know how big these are, also the fridge. Immediately upon power restart this is when the power requirement is the largest. All your motors will be trying to start at the same time. You need to ensure that you have sufficient power to start these motors. At a guess, I think 10kw should be sufficient quite comfortably. A portable 6kw gen set may require some messing about with breakers. IE. you only start one motor at a time. Hence the power surge demand is spread out over time.

The other useful thing to remember, or your electrician should know is that your generator set actually generates power as two phases. Huh? What is a phase? Imagine a smooth wave like line, in math it is a sine wave. Now imagine two of them. Just like waves on the ocean sometimes one wave is at a peak, and another wave is at a low point. Your generator will produce these two waves, two phases, and they will be perfectly out of phase with each other. One will be at the peak, while the other will be at the low point. OK now you are confused :) OK the simple thing to remember is that most things you want to power up will be a 120v one phase item. You need to try and evenly divide these items on each of the phases. Sometimes one thing is a power hungry one. This will use up a lot of power on one phase. You cannot borrow power from the other phase. Because you cannot borrow power, you have to size your generator accordingly. For example, a 12 kw generator can be thought of as two 6kw generators (one for each phase). Make sue that if you have a big power item, e.g. your cook top, that you have sufficient to power that one one of the phases.

This phase thing can be confusing, and there are some items which actually do use both phases, hence what I have just said in the paragraph above may not be applicable. e.g. Some well pumps are two phased powered.

Hence in general it is a good idea to have spare capacity in your generator set. This is expensive. How much spare capacity is difficult to guesstimate. My recommendation is to go for the more expensive class two gensets and stick with that. The reason why is that once you jump to class three the cost tends to almost double because of the genset weight on installation, and the genset cost itself.

If you have some key big power items, e.g. you cook top that you must have running, then maybe consider a class three genset setup. From can see from your post, I do not see any big items that would reuire a class three.

If you have central A/C and want to run that, then I would recommend a class three genset. May people go for a class two set up, and buy a window air conditioner which they can install and run for a few days while their central A/C is out.

You also asked in your post how log you can run a genset for. Well so long as you top up the oil etc. at a shot you can run continuously untill your fuel runs out. Fuel is usually the limitation. If you are on mains gas, then almost indefinately. My genset burns at max rate such that a 500 gallon propane tank will be depleted in 5 days. Note propane tanks can only be filled to 80% capacity, so a 500 gallon tank by volume, but only 400 gallons actual LPG propane. Then your tank may not be full, say half full. So right now I have a two day burn reserve. The flip side is you do not have to run your genset 24 hours. In power outages, I only run for say a few hours for showers, heating no burst pipes etc. The rest of the time if I am out keep it shut off if I am out etc.

You may want to run 24/7 however due to your sump pump and basement flooding risk.

Hope this is useful, and you are not falling asleep ....

All the best, Mike.

slateberry51 -- I didn't know there WAS such a monitor. Good idea!

stinkytiger -- OK, my DH wants to know about your user name. LOL And I want to say thanks again for all the help!

We're experiencing a 50-degree temperature gain with rain and fog over our two feet of existing snow right now. Glad our sump is new! It's Water World here. The normally shallow creek that borders our lot is raging and we have a little water in one crawl space. Woke up last night to thunder and lightning. It is supposed to go below freezing again tonight. Let's hope we don't lose power now, just as we are getting ready to buy a generator.

BUMP!

We've had one bid of $9000 for a Generac 5530 (complete install). On the 'Heating' forum sniffdog and I agree that is too high -- might be acceptable for a Kohler 12.

This is an easy install, right outside of the wall where our elec panel is in our basement. It's about 20 feet from our driveway. First bidder says the generator comes with a composite pad, so no concrete pour. The gas line is also right there so no big trenching required.

Second company still no response after leaving two messages. (We picked these two for their BBB ratings.) Found a third company with a BBB rating; rep is coming Friday. He says he prefers Kohler over Generac although they sell both. He also offered info on 'servicing', but I remember someone here said that's unnecessary -- right?

Thanks for the 'hand holding' here!

Hi Chisue,

I think you are going about it the right way. Get a few quotes and see. That is what we did.

As for servicing I think it depends on if you are used to messing about with engines. I do not have a service contract although one was offered by Cummins Onan / Metropower of New York. These guys are actually very good and I am very pleased with them. But that is another story.

My generator is basically a Ford engine. So far I have changed the oil, the air filter looks pristine so I did not change that. So far I have had like 17 hours total running time, hence I guess nothing really wears out. They may degrade due to time though.

Changing the oil is easy on mine, there is a tap. Literally a tap. You stop the engine, and drain it by turing on the tap. Close tap and refil with oil. That is it.

So far no issues. I figured if it breaks, I will call the guys out. It has not failed for two heading on three years, so so far so good.

One useful tip is to get some wire mesh and try and block up all the holes when your generator arrives and is installed. You install it typically in the spring
and summer when the weather is good. Most generators
have some keep warm heaters, and a nice dry enclosure. The issue is mice. Come Autum/Winter, they are looking for a heated nice dry enclosure, and generator housings are perfect. You want to keep these guys out if you can. Each spring I clean up all the mice droppings, and check for nibbled wiring. That is despite plugging as many of the holes as I can.

Best, Mike.

P.S. StinkyTiger, that name is all my wife's idea. We are a great fan of Calvin and Hobbes the cartoon book. I figured that if I were not me, I would like to be Hobbes :) ...

Mike

Thanks for the tip on the mice. I have been battling these pests since the fall and have been winning a tough war - never thought to check the generator housing. It is amazing how tenacious the mice are and the holes they find to get into my garages. Last thing I need is a stupid mouse chewing through power cables.

On the concrete pad - it might be a code requirement to have one (it is in my area), The reason is that you need to anchor the unit especially since it is connected to a gas pipe! The last thing you want is the unit to move, put stress on the line, and break it - not good. You also want the unit to be level.

I built my own pad using 12 bags of quickrite concrete and some 2x4's, with a little gravel at the bottom - not hard at all, maybe 2 hours of work. Make them put the pad in and then bolt the unit into the concrete in the holes they provide in the composite base. The holes are there for a reason.

Thanks guys! I'll get back here after we have another quote from the man coming Friday. I've made a list of all the points we need to cover before accepting a bid. Much appreciated.