Propane backup generator

[reb]

A nearby forest fire knocked out our power for nearly a day last week. That got the wife concerned, primarily about running the pump to ensure we had water for the goats. We are considering getting a 7kW propane powered backup generator to connect to our garage/workshop to run the pump and freezer. When it is needed, we don't expect to run it full time. Therefore, to simplify the installation, we figure to get a couple of portable propane tanks instead of plumbing it to the household tank. While researching generators, I noticed that some people have had concerns that their natural gas supplier might not guarantee adequate pressure for their natural gas powered generators. Are portable propane tanks likely to restrict the flow too much for a generator?
Thanks ahead of time for any help.

 

[GRUMPA]

REB,
Your generator I would assume will be for emergency purposes only. Living in Az myself and having remote property in the north eastern part of Az we have 2 stand by generators. 1 being gas and one being propane, the propane type are a little touchy when it comes to the volume of propane they require for operation. Just one bottle of propane wont work when the generator is working under a load, I have to hook two of them when under a load of any type.


I know it may be a pain in the neck but consider hooking it up to your big tank (if you have one) it will provide it with what it needs to work properly. Mine is rather old (circa 1966) so these new ones (if you have a new type) my work a bit differently I'm not sure but I wouldn't expect it to be much different than the old ones per-se. Thats what I ended up doing.


If you are using it as back up you'll need to install a special switch on your main so that when its working you want zap the line guys trying to fix the power line. And one more thing, we use 5K generators with everything on (no A/C) we use only 1 third of what they're rated at.

Now we use only one generator at a time not both at once, dont mis-interpet that we use both at once and we have nothing thats 220V just 110V even our well pump.

 

[reb]

Grumpa:

Thanx for the reply. I assume you are using the small (20 gal?) tanks. Is it likely that larger portable tanks would provide a better flow?

As you assumed, the generator would be for emergencies only. The one we are looking at comes with the necessary transfer switch to ensure it is disconnected from the main lines. It is ideal for my setup. The garage/workshop has its own service panel, so the electrical hookup will not be difficult. Routing the household propane tank to the generator would be a major pain. The water, power and phone lines between the house and garage are all in the way.

The load won't require the full 7kW. I used a portable 4kW generator to run the pump while building the garage. It requires a big chunk of that capability to start the pump, but not much to run it. It just happens that the best deal I have found is 7kW. The price includes a weatherproof setup and automatic starting and weekly exercising. A quality (Honda or equiv) portable generator with the transfer switches and some kind of shelter would cost more.

 

[5030]

Ah yes, the backup gen set scenario....

During the summer last year, we lost our power as did most of the east coast and lower Michigan. I think it had something to do with free enterprise or whatever. Anyway, being a farming operation we have stock to water and toilets to flush not to mention freezers to keep cold and the air conditioning and furnace to run.........After 3 days, we were collecting rainwater (it did rain, thank heavens), sweating our selves to a major stink and getting really frustrated. As soon as the power came back on, I jumped on the computer and via the "information highway", bought a Generac 15KW propane fired standby gen set. www.generac.com I didn't get it direct from Generac but from an outfit in Arizona: For some reason, I can't get the URL right. Do a Goggle search for Norwal Power Systems. Nice folks.

It was delivered in about a week. I did the physical install, had my propane supplier hook up the propane (we have 2 500 gallon tanks). The propane installer had to put a regulator on the gen set as well as a shutoff valve. Cost me about $60.00. I had a Generac certified installer do the electrical hookup, hooking the transfer switch to the main panel. You need a certified generac installer to do this as the warranty on the gen set has to be validated by the installer. That cost me $450.00.

I run everything at the farm, furnace, well pump, tank heaters, air conditioning, shop, lights, barn....everything.

The unit cycles once a week at the time you pre-determine. Scheduled maintenance is every 6 months. An oil change (I use Amsoil 5-15 and an oil filter is all that is needed. The unit trickle charges it's starting battery so it's always ready to go.

Transfer time is about a minute after the internal sensors detect a power level less than 190 volts. That allows you to run through a brown out. The unit will continue to run until the power stabilizes at 225 volts for 3 minutes or more. The same scenario applies for a total loss. Transfer back to utility is instantaneous. The transfer switch is a double pole single throw, magnetically actuated unit and completely disables the utility from the standby power.

My 15 KW unit (30 horsepower) uses about 1 gallon of propane per hour at full load. It cost me $2500.00 not including the electrical and propane hookups.

I'd suggest hooking the unit directly to your bulk tank. Portable cylinders won't provide the delivery required of a gen set.

Finally, get the 15KW unit. The 7KW unit is only about $300.00 cheaper. With the 15KW you get a twin cylinder engine versus a single cylinder and almost twice the reserve capacity.

 

[Junkman]

Here is a link to Nowall Power..... web page . I presently have a 8 KW Propane generator running a Tecumseh single lung noisy engine. It spins at 3600 RPM and it is so loud that it revived one of the dogs that died 5 year before!!! /forums/images/graemlins/grin.gif If you get a generator, make sure that it runs at 1800 RPM. Much quieter. I would upgrade ours, but since we installed it, there hasn't been any power outages lasting more than an hour. /forums/images/graemlins/smile.gif

 

[Slamfire]

A gas powered generator will put out more power than the same one powered by propane. By the time you deduct for the difference in "peak" power and continuous power, then deduct for the loss of power to propane, you won't have a 7kW generator, but it'll probably be adequate to run the pump, freezer and a couple of flourescent lights. Have you figured out how you are going to cook? /forums/images/graemlins/confused.gif

 

[reb]

</font><font color="blue" class="small">( Have you figured out how you are going to cook?
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You might note from my previous posts that this is emergency power for the garage. We don't plan to do anything for the house, beyond possibly finding a way to run the furnace in the winter. My wife is happy to cook on our camp stove in emergencies. Sometimes I think she wouldn't mind living in a tent as long as she has my company/forums/images/graemlins/grin.gif.

 

[Ches]

We have an 8Kw generator with a B&S 18 Hp VTwin engine. It was converted to run on propane. I have found that using the 20 lb propane tanks do not work well. The generator does work (and that is what I use for the monthly start-ups). After a while, the 20lb tank begins to freeze and the generator stops. The local propane gas supplier told me you need at least the 100 lb tank to prevent the freezing...something with the amount of flow being provided. Can buy a 100 lb tank (empty) at Lowes or Home Depot for about $90-$100, and about $55 to have it filled.

 

[5030]

That is not quite right....The 7kw unit is rated at 7KW on propane as is the 15KW unit. They derate on NG.

Propane gensets are designed to run on propane for convenience and less danger. Gasoline powered units are usually portable units while propane units are stationary.

Junkman:

The 3600 rpm units are 2 pole generators while the 1800 units are 4 pole. Ours runs at 3600 rpm but is in a soundproof attenuating enclosure. It's real quiet. I wnat a turnkey unit. One I don't have to fool around with. The Generac unit fill that bill really well. The added benefit is that my wife can run it.......It runs itself.

 

[GaryM]

I have the Generac 15KW unit running on Propane. Yes, at 3600 RPM it's not too quiet, but I can hear the TV fine and the air conditioning works fine too.

Didn't want to spend the extra cash for something I hope not to use too much.

I bought mine from the Electric Generator Store.