Stand-by generator search

jscozzAugust 29, 2011

I am looking to install a stand-by generator in the next couple months. When I built the house I put in a separate sub panel with all the loads that I want to power with the generator. I have geothermal, so pretty much all electric. I am looking for a nat gas unit between 30 and 39 kw.

I have looked at Kohler and Generac. I like the generac QuietSource 36kw unit very much... BUT, it lacks the automation that the Kohler units have... ie. the ethernet interface and PC software that gives you monitoring, control and alerting of issues... also looks like they show an iPhone app on their web site, but I can't find any proof of that. Teh Kohler units only come in 30kw and then jump into the 40s.

I called Generac and they said they have no such interface... and none planned.

My question is... are there any other models in the range I am looking for that have this automation? For those of you with Generac units, does it have any capabilities or interfaces to get data from the controller?

I'd also like to hear from anyone who has looked at these models (or others) or owns a Kohler unit.

Any advice would be appeciated.

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Ron Natalie

I have a 80KVA GENERAC, it has a computer interface but I've never got around to doing anything with it. On the rare time I want to know what's happening, I just go look at the control panel on the unit.

    Bookmark   August 29, 2011 at 12:59PM
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The K.I.S.S. priciple applies very well to standby generation. The fewer bells and whistles your set has, the less there are to break. (note- this statement is not in any way an endorsement of the Generac product)

You can "save" some money by getting a 3600RPM unit with a smaller engine, but whatever brand you buy, you will probably be a lot happier if you get one that runs at 1800RPM. Also be sure the set uses an engine that you can readily get parts for. In the range you mention Onan currently uses a 4.2L Ford and Kohler a 4.3L GM for 1800RPM sets. I haven't any idea who really makes the 2.4L turbocharged engine Generac uses.

    Bookmark   August 29, 2011 at 8:40PM
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Here is a website with generator reviews. It's kinda like Consumer Reports, but you don't have to pay to read it.

They seem to like the Briggs and Stratton for big generators. But the customer reviews say the customer service stinks. So I guess you have to hope you don't get a bad one. Generac seems popular, but I saw a lot of bad customer reviews on that one too. I guess you are taking a chance on any brand. I have a NorthStar 5500 with a Honda engine which worked great for ten years, but just pooped out during Hurricane Irene.

    Bookmark   August 30, 2011 at 11:05AM
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Hello JsCozz,

Looking at your specification it looks like you have quite a large demand need, 40kw. Is this for a business?

I have a Cummings / Onan RS 20,000 which I purchased over 4 years ago now. Runs well. It has a Ford engine in it and is Propane run. I purchased from Costco because they were the cheapest around. Note that for this size of generator instalation the most expensive cost will be for instalation rather than the generator.

warmest regards, Mike.

    Bookmark   August 30, 2011 at 11:14AM
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Re a Kohler generator. This is our experience so far. We installed a kohler 20RES in Dec. 2010It was very expensive.
It ran the exerciser weekly and then last winter had a power failure and generator did not work. error code showed under speed. rep came out and said something was catching and fixed it. I checked it weekly to make sure it was going through the test. seemed fine. This past weekend hurricane and power failure. generator kicked in perfectly for one hour and quit. Error code showed overspeed. i started it manually and then it quit. Rep came out monday and spent 6 hours diagnosing but could nor repeat the problem. said he ordered a part a mag? and would replace it this week. So two power failures and two generator failures. we did so much research on this and everyone advised against the generac for lack of service and mechanical problems. The diagnostics are supposed to be great on a kohler. We havent had this for one year yet and we have not been able to use it. Thats our story on this kohler. The tech said its been working fine til now. I said it has been running the exerciser fine until now. Thats our experience so far for what its worth. if they fix it and it fails again we are not prepared to keep it. 5 year warranty.

    Bookmark   August 31, 2011 at 5:17PM
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Generac's original line of air-cooled home generators, like the one I bought in 2000, didn't help their reputation. My generator dealer, a knowledgeable and trustworthy guy, says the current line is much better. I got one last year. It's certainly built very differently from the old one, and has better voltage and frequency regulation.

You don't have to wait for a power failure to give your generator a good workout. Shut off the breaker in the main panel that feeds the generator sub-panel, listen for the failover to occur (generator start, and transfer switch clunk), and then let the generator power the covered circuits for a day or two.

    Bookmark   August 31, 2011 at 6:55PM
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It seems to me that the quality of Cummins (Onan) and Kohler sets have declined in recent years, while Generac has improved. But, they have not improved to the point where I would install a Generac in a critical application.

    Bookmark   August 31, 2011 at 10:41PM
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Ron Natalie

My generac fires up and runs every Thursday at 1PM. Periodically, I go through the big disconnect and watch the thing auto start.

    Bookmark   September 1, 2011 at 7:40AM
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I like Cummins/Onan. My RS 20 has worked fine for over 4 years. Note however that it is a RS 20 with a Ford engine. I noticed on the Onan Web site that there is now a RS20A. The new RS20A is a lighter unit based on a lawn mower engine.

Onan and Kohler both bought out these lawn mower based engine gen-sets for the Residential Standby market. They are lower priced, and hence have the associated performance constraints.

An easy way (and somewhat crude) and quite effective way to judge the quality of a generator is to look at the weight of the generator. Heavier is better. Why? More copper in the windings, cast iron engine. Also be suspicious of high KiloWatt ratings while light weight. The manufacturer just pushes all the tech to the performance edge, stressing components, and hence the reliability issues.

They way I think about gen sets is if you maintian them well. Change oil, clean just like a car, and do not stress them then they will perform. BUT they are a pain to maintain and expensive. If you do have a gen set, exercise them. Then when the power blackout comes, run them gently. I.E. not too much load on at once. And shutdown over night when you do not need them.

Over the years I have also seen Gen Set KW ratings increase. The Propane units manually installed by manual labour, (no heavy lift required), initally all started in the 8Kw to 10kw range. I now see the same set ups rated 15kw to 20kw. Clearly there is some "yeah lets push the envelope here."

For relaiblility I would over spec at installation, and under use when the power cut comes. If you do this you will be fine. Note also if you do this, this is expensive.

My recomendations are, (prices include installation):

1) If under $US 4000. Stick with a petrol instalation. 6kw power. Minimial get you by performance. Best on market Honda inverter. 6.5kw rated. Cost $US 4,000 just for the gen set whic pushes you over the budget a bit.

2) If under $US 12,000 propane, no heavy lift. Rated 15kw. Actual maybe 8kw continuous use. Auto start. 3,600 rpm (bad due to faster revs)

3) $US 17,000 and over, then car engine. Auto start. rated 20kw and up. Continuos use maybe 12kw. Propane 1,800 rpm (good slower revs more reliability)

Best, Mike.

    Bookmark   September 1, 2011 at 9:43AM
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Thanks, all!

I am going to install myself... and I already have all circuits on a separate panel... so my only costs will be generator, switch, permits and wire. So I am willing to spend 10-11K on the generator if I need to... but I do not want to spend more than I really need.

The more I have researched this, the more I believe I can get by with a unit in the 20's. My biggest load is two geothermal units at 30A each... and 1HP well pump that runs with them. But I can get by with only one running on backup power (1st floor) and put it on a load control module also, so it gets turned off if I start to approach full load on the generator. 3 refrigerators, various lights (mostly all CR6 LED cans)... I am in the process of getting power readings on that sub-panel to see what I am really using.

I was set on a 1800 rpm liquid cooled unit because my understanding was that they are the most reliable and quiet units. But, I am wondering if I should be considering a largest size (20kw) air cooled (I'd prefer to be in mid 20's but no air units that large). When our power goes out it is usually out for between 1 and 3 hours. Was out 16 hours for Irene, but that is out of the ordinary. I am in an area served by very old power lines and equipment from the substation... so I want to make sure my generator can run for 24-48 hours at least without issue. Will I run into any problems with an air cooled unit?

    Bookmark   September 4, 2011 at 3:28PM
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Will I run into any problems with an air cooled unit?Probably.

But water cooled sets offer their own set of issues as well. No generator installation (of any brand) is 100% trouble free every time. The thing to remember is if you shop based only on price, you will probably get "the cheapest" set in more ways than one.

Consider backing up to square 1 and deciding if a power outage in simply an inconvenience, or if in fact it is an emergency. I don't mean the "I'm in an iron lung" sort of emergency (if that is your case then you need 2 GOOD generators and someone on call to repair same), but more the my basement will flood, I will lose big $$ because I can't work from home or I have $20K worth of fish in an aquarium situation.

If you decide it is merely inconvenient, buy the 20kw air cooled set, and get an extended warranty with same if possible. Figure on needing the warranty about the third time the lights go out for more than 2 hours.

If "emergency" is your decision, get a 30+ kw water cooled set made by Onan or Kohler.
Figure on paying the generator company $6-800 a year to maintain same, or learn to do the work yourself. Buy some oil, two sets of all the filters and spare belts. Get hold of a spare voltage regulator, because when you need one it will be out of stock.

    Bookmark   September 4, 2011 at 5:26PM
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OK. I have decided on a Kohler 20RESL. But i am having a heck of a time getting information from Kohler. I am going to buy online... and all Kohler will do is send me to a local dealer for info... which I am not quite sure why they would want to help me when I am not going to buy from them... Does not make sense that Kohler can't answer these questions for me directly.

If anyone here can help, I'd appreciate it...

1) The 20RESL comes with a transfer switch. Docs say RRT, 200A, 3R enclosure with no load center. Is the RRT the best Kohler transfer switch? Do their other ones have any other features that I might want to get the generator alone and different transfer switch separately?

2) The 20RESL comes with DC controller... the 20RES (no ATS) comes with RDC controller? Anyone know what the heck the difference is?

3) I want the OnCue software... but the docs imply that it requires an interface board that goes in the generator (ethernet connection). Does that board come with the generator or with the oncue software or separate from both? I have no idea what to order... generatorsdirect and lowes do not list OnCue as accessories at all.

4) Kohler docs say the carburetor heater is recommended for below 32 F... again, I find no listing for it to order. Is this really worth the $$ spent to keep it warm all winter? is 32 really the threshold or will it reliably start without the heater at lower temps?

5) Can these units be run at full rated load continuously? ie. this unit is rated at 18kw on NatGas. Can it run continuously at max load for a few days if it had to without issue, or should all my load calcs be done assuming only 80-90% load?

6) I have been told that an air cooled generator will not have any issue running for days continuously unless the outside temp is > 90 degrees, in which case it might have to take breaks to cool off... is this accurate? So in winter it would be fine with an extended power outage... but middle of summer may have issues?

7) Specs show peak motor starting kVA at 40.5... so I am guessing that if generator is near full load and my well pump or geothermal unit continuous current would max out the 18 kVA during run time, it will still be able to handle the inrush from them starting... is this correct?

8) Can't seem to find out if Kohler has any kind of load shedding devices the ATS can control... ie. an inline switch I can put on my geothermal to shut it down if other more important loads start to exceed full gen load. Most other manufacturers seem to have these device... outside the transfer switch... but I see nothing from Kohler...

Thanks for your help!

    Bookmark   September 30, 2011 at 12:00PM
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Hi Jscozz,

Looks like you are looking for quite a high end set up. These, like the Kohler are 1,800 rpm, water cooled car engine based units. Most of these units do have all the bells and whistles, like the ethernet hookup, Onan have them too.

It really depends what you want from your gen set. The ethernet connection is often used in remote sites, e.g. Cell phone towers which can be monitored from a central base station. You can have this option installed if you feel you need this feature. Will you be away from your home alot?

The transfer switch features you need is mainly a capacity constraint on the AMPS. The reason why is that it is difficult to "shed load". So the only way most local code allows now is that the gen set, and the transfer switch must be able to power all on that circuit. So typically this means having a sub panel, or a dedicated panel which will allow all the circuits to be gen set powered. The load limit is enforced by the number of circuits on that sub panel. I.E. you choose the circuits to be gen set powered, and those circuits are the only ones that the genset will power. Hence no way of overload.

On my Onan, I do not have a carb heater. I am in New York State, Westchester County, 30 miles north of New York. The Onan does have a coolant heater. I have never had issues starting in winter. I use Mobil One Synthetic oil. I tend not to run my gen set 24-7 in a power outage mainly because of cost. The propane usage rate is about 3-4 gallons an hour. Hence a full 400 gallon tank will be depleted in about 4-5 days. If your tank is only partial full, the run time would be less. So you need to conserver that propane resource. I only run for a few hours in the evening usually.

My 20kw set can handle a start up of a smaller central air compressor. Note the gen set during start up will not supply rated +/-120v, two phase 120v. It also only has to supply this surge current for a fraction of a second. It is sort of unlikely that everything starts at the same time, even at gen set start because there are usually fractions of a second delays before all the circuits cut in from the controls circuitry which needs to "boot " up. E.g. the well preasure sensor has to come online before your well pump will kick in etc.

Ohhh my car service is done. Got to go.

Best, Mike.

    Bookmark   October 1, 2011 at 8:49AM
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The 20RES and 20RESL are both air cooled 3600RPM sets. They are Kohler's response to the similar Generac product.

    Bookmark   October 1, 2011 at 10:59AM
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Any feedback from Honda owners would be appreciated.

I am having a heck of a time getting info from Honda or the local distributor... Honda has none to help me and only points me to distributor... distributor has not returned call for 4 days... and multiple messages. It should not be so hard to give them my money.

    Bookmark   October 4, 2011 at 1:04AM
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I do not have a Honda generator. However a friend of mine did. I think the one you want is the Honda EU6500iS. My friend had an older model. This is not a cheap genset with a MSRP of $US 4,500 for a 5.5 kw nominal output 6/5 kw max. He used his for whole house power backup and could run his well pump, and power up his oil heating forced air system on it.

Do not let the seemingly low output numbers phase you too much. I think they are being conservative here after the lawn mower fiasco (Industry wide, Honda, Lawn Boy, Husquava all claimed too high power ratings for their mowers which ended up in a class action lawsuit). My friends older model was rated 6.5KW with a 7.5 KW max.

This unit is nice in that it is an inverter unit. So it can run at the optimal RPM and give you 60Hz output. It does this with power electonics which also gives you a clean output good for Computers etc. Cheaper gen sets run at 3,600 rpm. Teh unit is also nice in that it is nicely shielded, so that I think it will fare better in rain and snow.

Other optional features include electric remote start. So you can put the unit outside your garage. Shut the garage door and have the control cable inside your garage. Then to start it is a push of a button. Useful if you are in your pyjamas.

The engine is a good one from Honda's commercial line, a GX 390. These are better than the GS line engines which is on the Home Depot lawn mowers.

Note this is not as powerful as the stationary propane powered units and you will only be able to run a limited number of circuits. However price wise petrol gen sets are alot cheaper to install and for a "get you by" the odd power outage it is a popular solution, mainly because of price.

Hope this is useful.

All the best, Mike.

Here is a link that might be useful: Honda EU6500iS

    Bookmark   October 5, 2011 at 9:14AM
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tiger... thanks for your feedback... though, I don't want a portable generator... I want standby generator on Nat Gas. A 20kw nat gas generator is about the same price as you mention above. No fuel to run out. No intervention required to get it running... powers all circuits I want powered. Will run as long as I need it to without having to go get gas or propane (which in an emergency may not be easy to get right away). And since I am already wired up for a standby unit at my panels, it is a simple installation. I appreciate your feedback, though.

    Bookmark   October 5, 2011 at 1:49PM
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Ah OK. I think Honda does not make Propane generators for sale in the USA. However there are companies that make Honda Engined generators. They are however no Authorized Honda dealers.

best, Mike.

Here is a link that might be useful: Honda engines 16KW

    Bookmark   October 6, 2011 at 8:15AM
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I finally got a call back from my local Honda Generator distributor... a couple things they told me I am curious about:

1) They say the 20RES they sell is different from the 20RES that Lowes sells... I find it hard to believe that Honda makes two different 20RES models...

2) They sell it with a 100A transfer switch... because they say the 200A transfer switch that Lowes includes with the 20RESL causes some code compliance issues... my understanding is that the code issue has something to do with the generator being able to handle the full load it can be presented with... which would only seem to apply to a 200A xfer switch if it had a built in load center... which the one I want does not. So it should not matter what the xfer switch capacity is... only the total load in my separate backup load panel. Right?

    Bookmark   October 6, 2011 at 1:05PM
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Sorry... I see my mistake above... and why tiger said there were no dealers in US... I mistakenly said "Honda" generator... when I meant to say Kohler... My mistake! Sorry for the confusion... everything I have been referring to has been about the Kohler 20RES generator... sorry!

    Bookmark   October 6, 2011 at 1:08PM
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There are many companies (amoung them Wayne, Moen, Kohler and Cutler-Hammer) that make or have made special models just for a specific reseller. A few years ago Kohler's 12RES models had electronic governing, and its 12RESL counterpart (made just for a certain retailer) did not. When a company buys many hundreds of a given product, they can get it pretty much any way they want it.

Years ago my sump pump quit on Saturday afternoon. I went to the local hardware store and they had a "Wayne" brand 1/2 hp pump for about $100, for the purpose of this story lets say the model was PUMP123. I decided to go check out WalMart and sure enough they had a Wayne 1/2hp pump for $60 or so, but when I picked it up it weighed much less-model PUMP123-WAL. I would never have noticed had I went only to WalMart- back to the hardware place and $100 later I had a good pump. A call to Wayne confirmed they made that "cheap" pump just for WalMart.

When you buy based on price, you often get what you pay for. Those extra letters after a model number mean something- the trick is finding out what.

    Bookmark   October 6, 2011 at 6:51PM
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