Assessing the DIY Generator

On July 8th of this year, Hurricane Beryl swept directly over Houston, leaving two and a half million people without power. The eye passed over my house, and our power and Internet was knocked out for 80 hours, in large part because of trees downed across lines strung along a heavily wooded and somewhat overgrown road. Houstonians love their trees (I do too) and with the weather this close to the gulf, the generator I installed last summer has already been pressed into service five times, including the May 16 derecho that also left a million people in the dark. But Beryl was the first prolonged outage that forced us to really put the new emergency power system to the test, and so I thought it appropriate to post a little report, in case anyone cares to learn from my experience.

I’ve posted before about the generator installation and the isolated emergency circuits through which it connects to the house. The short version is, I didn’t want to spend the cost of a small car on a whole-house generator, but I didn’t want to leave my family with a complex, potentially hazardous system when I’m not around. So no hauling a generator out onto the patio and running heavy cabling through a window, and no connection through the house breaker box and confusing cutover and circuit allocation. The generator plugs into the house as if it were an RV, and has its own circuits and breakers. The family only has to plug it in, fuel it, start it, and make use of the for red emergency power outlets in the house.

Observations

So how does it work in practice? Very well. It takes only a few minutes to start up, even in the midst of a storm, and just a few minutes inside to switch over the frig, internet, and my office computer if so desired. What takes longer, and what Beryl gave us the first test of, is pulling the portable AC out of storage and creating a single-room family “storm home” around it. I’ll leave the details of that to the imagination and share the lessons and observations:

• First, always keep gasoline on hand. I have 17.5 gallons worth of gas can storage, but I’d gotten lax and let my stores dwindle to only 2.5 gallons in one can plus about that much in the generator. That was dumb. It should come as no surprise that after a hurricane passes over your city, you can expect essentially all gas stations to be out of operation for two days. They might be open, but most are not pumping gas, and those that are are not taking credit cards. So…
  • Keep on hand enough gasoline to run the generator for at least 48 hours. Make sure you have at least one can you can use to safely dump unused gasoline into a car, because you’ll want to keep stores gas on a rotation so that it doesn’t get too old, break down, absorbe moisture, etc. and the obvious way to do this is to keep one or two cans full of gas that can be burned in a car and replaced every few months, only filling any additional cans before a forecast storm—just get off your butt and go fill them when the time comes!
• Second, you probably don’t need as much power as you may thin. Having a working frig, one lamp, and one fan makes a HUGE difference. Add in a little electronic entertainment and the odd small appliance, and days of sweltering misery have become a minor inconvenience. You might need the fan to sleep, and you might not be as comfy as you’d like, but you’ll be fine.
• My little generator can produce 3,500 watts continuously or 4,000 peak, and it’s an inverter generator completely safe for electronics. It has an economy mode that causes it to throttle to meet the load.
  • Powering only the refrigerator, the home Internet equipment, my office computer, and a couple of fans and lights, it can run 12-15 hours on 2.5 gallons of gasoline.
  • Powering all this, plus a small portable room AC, the TV and disk player and assorted video games, the same fuel only lasted 8-10 hours.
• We put the AC in our family room, open to the kitchen and surrounded by old, leaky windows and ran it in its default mode with the thermostat set to 78. It held that temperature over night, and with daytime temperatures in the upper 90’s, kept the room below 81 and the humidity level comfortable at all times.
• We did not activate the AC’s “turbo mode” that basically makes it just run flat out all the time and cool at much as it can. We could have, and I did test is after the mains came back on and the generator seemed to have no problem with it, but it would have burned through a lot more gasoline.
• That’s important, because as some of my coworkers learned the hard way, larger generators can be impractical or even impossible to keep fueled during a major area-wide recovery. With the AC running, we were comfortable and using a hair over 5 gallons of gas per day, which after the first two days was easily replaced and could have been maintained indefinitely.
• The AC extracted almost exactly 10 gallons of water per day from the air. If we had to, we could have run it through a filter for drinking.
• I did run into a problem during the previous storm that I finally figured out this time: like most modern generators, this one have a fuel tank vent designed to equalize the air pressure inside the tank. Mine doesn’t work, so as the generator burns gasoline, the air pressure inside the tank can drop enough to kill the engine. Leaving the gas can loose solved the problem, but the valve need to be replaced. I’m not 100% certain there is really a good reason to have that valve instead of the little breath hole that small engine gas caps had for a century, but whatever–technology marches on, right?

Lessons

The system works exactly as planned, but there are a couple of things I didn’t think of:

1. 1. I need a better surface to stand on when tending the generator during a storm. I did a good job on installing it high, dry and stable on its little foundation, but to access it during heavy rain, I have to stand in an inch of water. Not good.
   2. If you live in a colder climate but have natural gas heating like we do, you might want to have a way to switch your furnace blower over to generator power. In such a system, the heat comes from the gas and the central blower doesn’t actually use that much power, and there are YouTube videos showing how to heat your hole house using a car battery and an invertor. I opted not to bother, as the Houston ice storm a couple of years ago was a once-in-a-century anomaly, and any freezing temperatures here are rare. We have a little heater and a gas fireplace, that’s enough.
   3. We have a gas stove, but in post-hurricane heat, in an uncooled or undercooled house, do you really want to use it? I could have rigged a way to switch the built-in microwave to generator power, but it might be simpler to just buy a tiny microwave over to store away for emergency use.
   4. When installing a generator in a DIY shed, give extra planning attention to servicing requirements. You need to be able to not only refuel it but:
      1. Drain the oil
      2. Refill the oil
      3. Replace the spark plug
      4. Clean the air filter
      5. Remove the whole generator for servicing or replacement.
   5. In my case, none of these are a major problem after installing an oil-drain extension hose to I can drain the oil into a buck instead of directly through a plug beneath the crankcase–but I got lucky. I really didn’t plan that as well as I should have.
   6. Buy a flexible exhaust hose made for generators. My jerry-rigged exhaust plumbing works fine and is safe, but it will be a pain when I have to remove the generator.
   7. Buy or build an exhaust riser stack. Mine is a second-hand model bought on ebay, and it’s fantastic. It’s in three sections, the bottom one of which it permanently mounted outside the generator shed. The other two fit inside and are easily and quickly set up for use. The riser does an excellent job of lofting the engine exhaust up about the fence and the roof to where it can rise and be carried away on the breeze. All throughout this recovery, the only exhaust I smelled was from a neighbor who just put his generator on his back patio.