Home Generator System ???

   / Home Generator System ??? #11  
@hr3: Great and concise fuel estimating data! tnx!

Regarding my generator size, I got it at the old house which was all electric and had two 3-ton and one 1.5 ton heat pumps. It was cheaper to buy more generator and transfer switch than it was to replace appliances. The generator cost estimate I gave was at todays cost. Back in '97 when I did this, it was $10K for a 25 KW generator (4 cylinder) and $12.5K for a 45 KW generator (6 cylinder). The resistive electric heat on the heat pumps blew everything out of the water, hence the new panel before the xfer switch. To reduce the load by 20 KW would mean all new stove, oven and hot water heater which is greater than $2.5K.

Note that this is also why I hate pricing by the kilowatt of capacity. The analogy in tractor land is comparing prices of a 48 HP tractor to a 26 HP tractor. The 48 should Not be 85% more, it would more likely be about 40-50% more. And other factors (such as transmission, frame size, tires, cab and options) are more of a factor that HP.

The 2-3X cost of generator and transfer switch is a first order estimating tool because these are two things that are easy to price. If that price passes muster, then a more detailed estimate based on pad cost, tank cost, wiring cost, labor, etc. can be done. On the packaged systems (like many of the Generacs) you can't break out the cost, but that's OK because with the generator/xfer switch priced as a package, you're down to siting cost (pad, fuel) and retrofit electrical work estimate.

New comment based on OP information: If the user is required to stagger usage, check to see if the heavy use appliances power up in the off state. If you have a power failure while some of these things are running, when the generator kicks in 10 seconds later it may see too much load. Newer appliances like stoves and ovens have electronic controls that power up off, even if it was a couple second outage. HVAC equipment want to keep on going. So in addition to getting a current draw on your appliances, make a note of how they handle a power fail and if they come back on in the same state (mechanical timers) or come back on off (electronic control). I would say that many times a year one is baking a pie, cooking a meal, drying clothes, and the HVAC is going.

Pete
 
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   / Home Generator System ??? #12  
Deer hunter, Good morning.

3 things you might want to consider.
First. Cold weather starting of the gen set. If it's really cold, an air cooled gen will start up under full load and full RPM. Not to good on a cold engine. A liquid cooled gen with a block heater will live longer under those conditions.
Second. The running RPM. A 3600 vs 1800 RPM. 1800 running RPM engine will live longer.
Third. Initial cost vs amortized cost. That is where the buck stops.
Have a great day! Dave
 
   / Home Generator System ??? #13  
Deer hunter, Good morning.

3 things you might want to consider.
First. Cold weather starting of the gen set. If it's really cold, an air cooled gen will start up under full load and full RPM. Not to good on a cold engine. A liquid cooled gen with a block heater will live longer under those conditions.
Second. The running RPM. A 3600 vs 1800 RPM. 1800 running RPM engine will live longer.
Third. Initial cost vs amortized cost. That is where the buck stops.
Have a great day! Dave
The full automatic generators do not start under full load. They have a warm up period before transfer switch switches to generator. I do not think someone in MO would need to worry about a engine block heater.
 
   / Home Generator System ??? #14  
We switch our generators over to synthetic after their first year or so. That will help with the cold weather start ups.

Ken
 
   / Home Generator System ???
  • Thread Starter
#15  
I forgot to mention there is already a 500 gallon LP tank at the location, the house is heated with LP Furnace , everything else being electric.

So the additional cost is just for a Concrete Pad and 15-20 foot of gas line, appropriate Auto Switching , Wire, and Electrician for installation.

The mention of Cold weather startups and a block heater, on occasion we see temps in the 0's-10's for 1-2 week spell. Our average is 20's for lows in southern MO (where the Gen will be located) .



HR3 , sounds like you sell GENERAC's

Is there a option to set when a Power outage occurs. The Engine would start , run for "x" Min at warm up idle, then engage the Gen. and increase to Operating RPM???
 
   / Home Generator System ??? #16  
Yes our company does sell Generac and Kohler ;)
I work for a company that is an Electrical contracting outfit.. The boss started selling them about 8 years ago as a side line.. Now we put in about 350 units a year and service about a third of what we install..

As far as warm up time.. Don't worry about it.. If your going liquid cooled 殿nd it sounds like you leaning that way?. Have the block heater option installed,, Don't get the whole cold weather option because it comes with a battery heater too and I've seen too many batteries cooked by them.. BTW the 45 kw on up does have a delay transfer option but is only used in a 斗ead lag setup .. 典ime Warner does this once and a while...

Good luck and happy hunting...
 
   / Home Generator System ??? #17  
We are colder than that, and two thirds of our customers do not install the heaters on the air cooled units and are fine so far. Again, a synthetic oil would make for easier winter starts.

Ken
 
   / Home Generator System ??? #18  
Deer Hunter, Good morning. Synthetic oil can be a good thing.

However, you should NOT use synthetic oil until your engine has at least 50 hours of running time. It will wear out your engine in no time flat.
A friend of mine built racing engines. He would test them on an engine dynamometer to document performance for the client. Torque range etc.
On one engine he used synthetic oil at start up. The HP and Torque was incredible. He had never built an engine with those kinds of numbers. Succesive engine runs showed the HP and torque in a serious decline. He disassembled the engine and it looked like it had run 200K miles. This engine was identical to others he had built. He called the manufacturer to ask why the engine was worn out and explained the entire situation and process.
The manufacturer of the synthetic engine oil said the syn oil had no high pressure lubricant in it. You must break in the engine with regular oil to wear in the parts. This process "mate wears the parts" that machining cannot accomplish. After the parts are "wear mated", syn oil does wonders reducing friction and high pressure lube is not necessary.
I was in the machine the shop during the dyno runs. I saw the HP decline. I was not on the phone to the syn oil rep but had the conversation relayed to me.

All that said, I have used syn oil in equipment. My motorcycle went from 35 mpg to 50 mpg. Syn was used in the engine and tranny. Used properly it can do wonders. Others will probably respond that they have never seen the problems I presented. If you have any doubts, contact the technical services dep't of the oil manufacturer you will use.
Syn oil may have changed in the last few years. Some very well could be OK to use at breakin.
Just my 2 cents from first hand knowledge.
Best of luck, Dave
 
   / Home Generator System ??? #19  
Depends upon the engine - some come with synthetic oil in them right from the factory. Some engines do not require the traditional break in. Having said that, we wait 50 hrs as well before using synthetic.

Ken
 

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