Stand by generators

[Recoveryhill]

Generators are like tractors you can never have one to big.

Disagree: A engine/generator set with capacity over that required is inefficient and at low loads damages the generator section.

 

[Toyboy]

I was just saying that my NG generator only requires pushing a lever to have it work with propane (obviously after some piping/fitting changes). I know they make tri-fuel setups for portable generators, but I'm not sure if anybody makes one for a stand alone designed for NG/propane. Based on my rough calculations, I think I figured out that I should be able to run my 20Kw setup for around 12 hours at half load using a 100gal propane tank, so I might eventually get a couple to keep on hand, and sort out the piping issues so I could drop them next to the unit, change connections, and be back up and running if something happens to the NG supply. Historically NG infrastructure has been pretty robust in all but earthquakes, so I'm not terribly worried, but I certainly do like backups, and options! R,

Your right that your Generac is capable of running NG or Propane just by moving a lever on the carb. But I don't know if the regulator is the same for the two fuels. I do know the pressures are set different for them. If the regulator is compatible, all you need to have handy is a gauge to reset the pressure.

 

[MESSMAKER]

Stand-alone 17kw Generac propane model here also.Been 4 years installed without any problems.Keep oil changed every 40-50 hours with 5W-30 full syn.oil adjusted valves.I paid $4,650 installed.Like others have stated get a load study done.

Wow! They require oil change every 40 hours?

 

[ETpilot]

Reading this thread I never realized that there was such a need for generator power. I have lived in my house 23 years and I have used the generator 6-8 times. The longest was about a week after an ice storm. Most power failures don't last that long. It takes 15 minutes or so to set up.

All this talk about generators, I realized it was time to test my HF. Started up second pull, battery not used. It will get a workout starting this week as I progress in my shed building project.

 

[3930dave]

Disagree: A engine/generator set with capacity over that required is inefficient and at low loads damages the generator section.

Water cooled/high capacity/low load/short runs, I can see the engine rarely getting up to temperature. At least in my climate, half the year.

What is the failure mechanism on the generator section, at low load ?

Rgds, D.

 

[Toyboy]

Wow! They require oil change every 40 hours?

I've had mine installed a little over 2 yr and has 26hr on the clock just from weekly exercise cycle. I did change oil & filter this fall. If the power did go out for days on end, I would do an oil change just for the heck of it. I will probably get into changing oil every fall now (2 qt), and if no major power outages occur, I'll do filter every 2 yr.

 

[GrandLakeGAR]

Disagree: A engine/generator set with capacity over that required is inefficient and at low loads damages the generator section.

Is this really critical? My Generac exercises 12 minutes each week at full speed with no load and may go months like that. During an outage loads may be very high during the day but extremely low all night. A 20 kW at half load probably uses less fuel than than a 12kw at full load. Since the portables all seem to be rated at half load for fuel use, they must not consider that a serious problem. Nothing I worry about for sure.

 

[GManBart]

Wow! They require oil change every 40 hours?

No, the manual says 2 years, or 200 hours of use, whichever comes first. I guess if you had to run it for a week straight (8.3 days technically) it would be a pain to have to change the oil/filter, but that would be a pretty small inconvenience under those sort of circumstances.

 

[GrandLakeGAR]

Generac manual says oil and filter change every 200 hrs or two years. Two qts oil, a $6 filter and about fifteen minutes. Clear access, filter out in the open, and a drain tube for no spillage or mess, I wish all my engines were this easy.

 

[s219]

Is this really critical? My Generac exercises 12 minutes each week at full speed with no load and may go months like that. During an outage loads may be very high during the day but extremely low all night. A 20 kW at half load probably uses less fuel than than a 12kw at full load. Since the portables all seem to be rated at half load for fuel use, they must not consider that a serious problem. Nothing I worry about for sure.

I think the main issue is wetstacking (http://cliffordpower.com/wp/wp-content/uploads/2011/12/IS_09_wet_Stacking_GENERAC.pdf), which is most known on diesels but can affect propane/NG engines too from what I have read. The main problem occurs if the generator is operating for short duration and light load and can never reach operating temperature.

As far as efficiency, my 21kW diesel generator has an Isuzu engine, and it scales down fuel efficiency extremely well at lower loads, to the point were there is almost no penalty for running at lower loads compared to having smaller generators. This was unique to Isuzu units; the Kubota and Mitsubishi powered units do fare worse when running under light loads.

 

[check]

Yeah, that $1.35/gal for LP is CHEAP! I just paid $2.50/gal for my 1000 gallon tank to be filled.

Holy smokes, I pay $3.22 per gallon at the cottage! Where can I buy a big tanker semi of that stuff at $1.35?

 

[check]

Disagree: A engine/generator set with capacity over that required is inefficient and at low loads damages the generator section.

I don't get it. Alll the dealers telll you to have enough juice to handle the (often huge) spike when fridges and the like come on, so I expect that most people's gens are running at less than half capacity. (Mine at the cottage is a 17 kw Kohler, because we have a hot tib.)

So what is the problem with lower
Loads?

 

[300UGUY]

[/I]
Your right that your Generac is capable of running NG or Propane just by moving a lever on the carb. But I don't know if the regulator is the same for the two fuels. I do know the pressures are set different for them. If the regulator is compatible, all you need to have handy is a gauge to reset the pressure.

I know my regulator on my propane unit is different than the one for my furnace. I have 2 lines coming from the tank, one to the furnace, and one to the genny.

 

[GManBart]

I know my regulator on my propane unit is different than the one for my furnace. I have 2 lines coming from the tank, one to the furnace, and one to the genny.

I would expect to need a different regulator for propane....not a huge problem, but something to be aware of.

 

[Toyboy]

I think the main issue is wetstacking (http://cliffordpower.com/wp/wp-content/uploads/2011/12/IS_09_[B]wet_Stacking_GENERAC.pdf), which is most known on diesels but can affect propane/NG engines too from what I have read. The main problem occurs if the generator is operating for short duration and light load and can never reach operating temperature.
[/B]
As far as efficiency, my 21kW diesel generator has an Isuzu engine, and it scales down fuel efficiency extremely well at lower loads, to the point were there is almost no penalty for running at lower loads compared to having smaller generators. This was unique to Isuzu units; the Kubota and Mitsubishi powered units do fare worse when running under light loads.

I don't think that would be an issue with any unit up to 20Kw (Generac that is), because they're all air cooled and warm up pretty fast. Now anything above that being water cooled might make a difference due to getting up to operating temp. Never thought about that before.

 

[GrandLakeGAR]

Holy smokes, I pay $3.22 per gallon at the cottage! Where can I buy a big tanker semi of that stuff at $1.35?

Dealers here usually have late summer, early fall sales, $1.35 was the sept price. They also provide pre booking for winter delivery, that was $1.65 in sept. Works well for people that have smaller tanks and can't go all winter with out getting more. The local price two weeks ago was $2.10 so buying pre booked was a smart move this year.

 

[hdmyers]

In Canada, everything is different. You can't shop for a supplier of propane.,.you are stuck with the one who gave you the tank. They all claim the system is safer this way... Uber regulation means high propane costs. (We went through 20% of our 325gallon tank over the Christmas holidays.... -20 will do that.). I called them asking them if i could just buy a tank instead of renting from them...the sarcasm from the customer service gal was funny...and these are 'the

cheers,

 

[Oiltech]

I don't get it. Alll the dealers telll you to have enough juice to handle the (often huge) spike when fridges and the like come on, so I expect that most people's gens are running at less than half capacity. (Mine at the cottage is a 17 kw Kohler, because we have a hot tib.)

So what is the problem with lower
Loads?

There is no problem running a generator with minimal load except for you could be wasting money on fuel by running an engine larger than needed.

 

[GrandLakeGAR]

In Canada, everything is different. You can't shop for a supplier of propane.,.you are stuck with the one who gave you the tank. They all claim the system is safer this way... Uber regulation means high propane costs. (We went through 20% of our 325gallon tank over the Christmas holidays.... -20 will do that.). I called them asking them if i could just buy a tank instead of renting from them...the sarcasm from the customer service gal was funny...and these are 'the

cheers,

We can either lease a tank to be serviced only by that dealer or buy one out right and be able to shop for the lowest area price. It's surprising how much the price will vary between dealers only a few miles apart.

 

[coobie]

Wow! They require oil change every 40 hours?

Just going by what my installing Generac dealer told me to do.