lpg genny

[LawAbidingCitizen]

(15 October 2013, 00:47)CharlesHarris Wrote: 900w really isn't very much power.

While portable inverter-generators, such as the Honda provide clean sine wave AC which is best for running computers and sensitive electronics, I am not aware of any such units of sufficient capacity, which are full service panel rated, adequate to power a whole-house system which includes your well pump, HVAC equipment, water heater, washer-drier, refrigerator, freezer, etc.

My home backup genset is not a "forever off-the-grid system," but intended for storm backup sufficient for 10 days to two weeks until its 500-gallon fuel tank runs out, I get an LPG delivery to enable me to keep going, or the AC mains come back up.
A smaller, portable backup genset must work harder at a higher duty cycle if you are running heavier loads such as refrigerator, freezer or air condition compressors, blower motors for heating, ventilation or air conditioning, etc. A smaller portable Honda and similar systems in the 5kw range might be fine for you in UK if you do not require HVAC equipment, are on a municipal water supply and have only a small refrigerator, some emergency lighting and a small TV or computer.

But realize also that portable gensets are not rated for continuous-duty, and not able to provide seamless failover in a whole-house set-up. This means that you must either isolate or stagger higher capacity loads from the system. For instance, an electric 50-gal water heater uses about 4500w, a well pump about the same in starting loads, ditto a heat pump. So with a smaller genset you must choose which pieces of equipment you need at the time and then alternate their use. Auxiliary power systems must be sized for the starting loads and not the running loads of compressors, pumps, etc.

If on municipal water, there is no well pump to worry about, so that simplifies things. If you don't have forced air central HVAC, but heat rooms individually, that greatly reduces normal load requirements. Having lived through a 2-week power outage during a record heat wave in which daytime temperatures exceeded 35 degrees C, and having lost over $500 in food which spoiled, I wanted a full-panel system able to run two 10,000BTU A/C units, well pump, water heater, washer, drier, refrigerator and freezer, etc. without having to make any adjustments to "normality." After age 62 you don't need to practice how to be uncomfortable anymore.

In winter here, food storage is less an issue because we can keep perishables outside on our screened porch. But we need to maintain a limited amount of electric baseboard heating, just enough to keep the water pipes from freezing when the house is vacant, as we have several months where the daytime temperature seldom rises above 0 degs. C. Otherwise we minimize electric heat use by using a kitchen woodstove and a gas fireplace, keeping wall thermostats set to 15 degrees C. and wearing sweaters. Just like living in Scotland!

The design intent for the backup generator installation was to "flip the whole house," maintaining a comfortable retirement lifestyle with as few inconveniences or adjustments as possible. I wanted a full panel rated system providing seamless failover without requiring any conscious action or adjustment. So, I sized the system larger than I needed to provide surplus capacity to run machinery in the workshop and a trash pump to empty the cellar if it should flood. For normal needs for the average US house I would not plan for less than 10kw, and for a farm or small business 20Kw is better so that the system does not have to run at full capacity all the time. Sizing larger than you need gives both surge capacity and better reliability because the unit does not have to run at maximum capacity.

At US rates, hiring the job out to a professional, installing a smaller 10kw vs. 20kw genset saves only about $1500-1800 on cost of the generator, unless you do your own site work, can make your electric connections to code, pull the needed local permits to get it inspected. The US cost of contracting a full turnkey system for 20kw vs. 10kw is only about 20% more. Keep your smaller LPG tank used for the stove and water heater and get a larger dedicated one for the genset, at least 2000L. By the time you the electrician and the gas company for the new tank, regulator, connection changes, etc. either unit costs about the same. Approximate US cost to contract the whole jon is about $8000 for a 10kw system vs. $10,000 for 20kw, this being for a full turnkey installation powered by LPG, with double-pole, double throw automatic transfer switch, including an annual service contract from the gas company, who installed it.

While fuel consumption is less with a smaller genset, a 10Kw using LPG uses 7.5L/hr. at full load. This is almost the same as a 20Kw unit uses at 50% load. A typical 10kw LPG unit consumes 6L/hr. at 50% of capacity. That means a 1300L LPG tank would last about ten days at 50% duty cycle if you didn't use your gas stove, water heater or fireplace. A 2000L LPG tank powers a 20kw unit for ten days at 50% load. To provide the same capacity the 10kw unit must run at 100% of its capacity consuming very nearly the same amount of fuel, give or take about 5%.

Useful info thanks. I do think though that you guys are on such a different scale to us in the UK. What I would mainly be using it for is to charge up deep cycle batteries in the event of power loss to then power a small fridge, lighting, basic communications/computer etc. It would be very useful to be able to use this indoors so as not to compromise OPSEC. Although it doesn't recommend using it indoors, I'm sure it would be fine with adequate ventilation as it would be pretty much the same as a camping stove or heater as it uses the same type of gas canisters.