Posted: 4/14/2008 9:43:07 AM EDT
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I'm on 3.1 acres with Aerobic Septic and a well pump (30 amp I think on it) 150 ft deep or so. I did the wattage calculation and can probably run both refrigerators, well, septic pump, electric water heater, a few outlets on a 10kw genny. If I want to do the central air I would need to go higher. I'm thinking propane since I have a 250 gallon propane tank already. Would I need another regulator? The Northstar trifuel at 13kw seems appropriate. It has a Honda engine, and is under $3k (just). If I put in a transfer switch, can I select what is powered? I see them with 16 circuits and 50 amps....I guess my real question is should I just go minimal. A few fans, a few lights, water pump, water heater, septic pump and fridges and use ceiling fans. I would think having more wattage available is better. I know when Rita hit we baked for three nights with no fans/no lights where we used to live. What is the consensus? Buy and 8kw and just use a few items. Damn water heater pulls something like 4kw? Ok, lots of questions, I just want to be ready and could use some opinions. I know I will definitely go propane and transfer switch. Should I just buy a couple of large propane tanks (most Gennys like 100 lb or better tanks) or should I just tap into the one that exists? |
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Something to ponder, propane is climbing fast in cost, and propane is not as effecient as gasoline. I was shocked when I saw how much it could cost you to run a genset on NG or LP. I would suggest looking at a diesel set as well, they are very effecient if you get a 1600rpm model. |
Fuckin A it's expensive. Made the mistake of heating our pool last year. Holy Shit! I guess I was thinking that I could purchase a few 100 gallon tanks of proprane. They store much better than gasoline and are very stable. Lock em in the shed and haul out when needed. I may just do that to supplement if the main supply runs out. Also another question. Since I'd probably have my generator on the back patio just on the other side of the wall from the breaker box, would the electrician just perf the brick wall for a place to plug into the transfer switch from outside? On that note I guess there is a limit on how far away from the tranfer switch the generator is placed...? |
If I was to go propane I'd go for the Generac that has all the bells and whistles and will cool you down just fine run it for an hr or several at a time and that 250 would last a long time. that's if it's for short term. long term go diesel. |
I think you already know this but they are 100 LB tanks not 100 GALLON tanks. A 100 lb tank holds about 23 gallons. What size motor does your well pump have? I suspect that it's on a 30 amp breaker (standard) but shouldn't draw nearly that much...even on startup. If it was drawing 30 amps, that's 6600 watts...an awful lot of power for a well pump. My mom's old house was wired to enable the use of a generator for her well pump. The well pump ran easily on a 5500 watt generator...didn't even bog it down much. Her well was 300 ft deep for comparison. If you have a 1hp 220 volt well pump (pretty normal size), you should draw somewhere around 750 watts running and around 2500 watts on startup. I just re-read your post. Since you only have a 150 ft well, there is a good chance that your well pump is smaller than 1hp so that's even less watts to run. An electric water heater draws about 4500 watts unless you have a fast recovery water heater and then it will draw about 5500 watts. I think you could run everything you have(spaced out) with the exception of the central air with a 7500 watt unit.....8500 watt would give you room to spare IMO. It's never wrong to go bigger but bigger will also use a lot more fuel. For as much power as you want, you really should consider diesel. It's going to be very hard to store that much propane for an extended power outage. I use my diesel in a torpedo heater for my shop building so I can rotate my supply. |
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Thanks for the replies..yeah I wrote Gallon instead of lbs.... Deisel is just more reliable? and/or is it that it produces more juice at less rpm, thus more economical? Sorry to seem dense, but I haven't studied this much. I know that locomotives are just big ass deisel generators as trains run on electricity, so it would make sense that there is an advantage. I may see if I can find a 10kw deisel.... |
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Consider the difficulties of fuel storage, and regular rotation before choosing your fuel type. Propane: Easy to store, and you're able to conveniently and safely store thousands of gallons if you so choose. A 1000 gallon propane tank can run a sizeable generator for several weeks. They also can be placed underground, and an underground propane tank of the appropriate size is aesthetically pleasing, protected from gunfire, and much less of a fire risk than most liquid fuels. The propane can also be used for heating, cooking, etc... and will thus get cycled out and replaced periodically with normal household usage (minor point: I don't think propane ever goes bad in storage, though there is a little bit of evaporative loss IIRC) It's worth mentioning that if you live in a high water-table area, you might have to appropriately site an underground tank, and anchor it with concrete to keep it from "floating" to the surface in a flood situation. Propane also has a lower energy content than gasoline, diesel, or other liquid fuels, so you'll require slightly more of it to run your generator. If you read the fine print in your generator manual, you'll find that the wattage rating of various "multi-fuel" generators is advertised based on the output from the highest energy fuels... and using NG/Propane will de-rate your generator's advertised peak wattage by 10-15%. Gas/Diesel: Hard to store, dangerous to keep near/in a dwelling, and liquid fuels go bad over time if not rotated out. Even if you use Sta-Bil, or other preservatives, you still can't just throw a tank of gas in your shed and expect it to be any good two years later. You can try to get an underground gas/diesel tank installed on your property... but good luck dealing with the EPA, permits, etc. Above-ground tanks are possible, but they're ugly, and IIRC they also require a concrete containment vessel to be built around the base in case of spills. Also, you can imagine the possible problems with having a visible gasoline tank next to your dwelling if trying to hold off hordes of looters... you're one bullet away from burning to death in a most spectacular fashion. Gas and diesel are high-energy fuels, so you get more bang-for-your-buck per gallon of fuel than with gaseous alternatives. You'll also get full rated power out of your genset. Gasoline and diesel have an additional advantage that gaseous fuels lack: the ability to power your vehicles, or vehicles of opportunity. Just a couple of things to consider. |
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If things get really bad for awhile, you might not be able to get a propane refuel but as long as you have gas cans and a way to get them to a fuel source, you can refuel. Getting gas stations up and running is a priority for the grid. Getting propane stations up and running isn't as high up on the list. You will use a lot of propane in a short time. Propane is a great fuel but I don't think that overall it makes a good generator fuel. If you have a use for diesel fuel in something else other than the generator, then I'd recommend diesel. If you can't use any diesel for anything, then go with gas and rotate your gas into your vehicles. I have a 55 gallon drum to store diesel fuel and a hand pump to pump it out. Total cost for the storage method for diesel? $8 for the drum, $30 for the hand pump, and $20 for the wheel kit for the drum. Diesel gensets produce a little cleaner power in my experience because the engines have more torque and don't bog down as much when a load is put on it. I don't think that you NEED as big a genset as you are planning on. |
I'd like to add some things to the above. Propane burns cleaner than gas or diesel so your engine should theoretically last longer. As far as propane having less BTU's (energy), you are correct, BUT, there are other items to consider. On smaller engines the power loss is lower than the loss on bigger motors. Visualize a curve type graph for power loss versus motor size. In addition, most propane conversions/setups for smaller motors utilize oversized regulators so the motor will never be starved for fuel and you will not notice the difference in motor HP output. Obviously consult the spec sheet like Grayman advised to get the actual numbers but in my experience on smaller gennys there really isn't a noticeable difference. I have a Yamaha tri-fuel generator and I can't tell a output difference with gasoline versus propane with my testing equipment. I have a propane quick connect fitting on the side of my house where I can attach my Yamaha to my home propane system (1000 gallon bury tank) and I also have several BBQ/RV size tanks when I need to be portable if I don't want to use gasoline. I have found that after using propane to power the genny I almost never use gasoline in it anymore. And finally if I recall correctly they now make a zero clearance 120 gallon propane tank. Unlike the other large tanks that require a 10 foot (?) clearance from any structure, the new 120 gallon size can be installed right against a building and there is no limit to the # of tanks you can have. And I do mean gallon not pound. The only downside is that they are not portable like a 100 pound size or smaller. |
Diesel just burns less fuel for the same amount of power. However, small diesels usually run at 3600 rpm just like the gas units. 1800 rpm diesels use even less fuel but cost a LOT more to buy. Here is my diesel generator. I've been very impressed with it. 
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