An Electrical EpiphanyIn the spring of 2002, we moved into our present home (a 1962 ranch in a wooded area) and found that the reliability of the local power delivery system was a bit below par. Frequent brief outages were a nuisance for running a computer or anything with a built-in clock lacking digital memory. The August 2003 Northeast blackout raised the question of how we would deal with a loss of our central heating during winter.
A neighbor had installed a system involving a gasoline-driven generator, automatic transfer switch, fuel storage tank, etc., for about $4,000, but that seemed like overkill. All we really needed was power for the oil-fired hot water heating system.
While adding several small UPS systems (essentially batteries accompanied by inverters to convert D/C to A/C power) to support computers and their auxiliaries, I found power storage options for feeding small plug loads (e.g., lights, radio, TV, small appliances) had improved in recent years. Those with power sufficient to fire an oil burner with a 12A startup load were, however, either too expensive or required special wiring. Once running, my heating system (new in 2002) pulls only about 120 watts. Since oil-fired hot water heating systems cycle intermittently (except on coldest days), a few hours of run time are typically spread across several days. Bottom line: a power source was needed that could handle a large startup load, but only needed to store a small amount of energy.
Enter XantrexXantrex Technology Inc. ( www.xantrex.com), is one of several makers of rechargeable backup battery systems for residential, small commercial, and mobile loads. Ideal for my needs was the xPower Powerpack 1500 (find it at:www.xantrex.com/web/id/63/p/1/pt/5/-product.asp). Essentially a 60-pound sealed lead acid battery on wheels, it has a built-in inverter, charge indicator, standard outlets, charger, etc., plus a removable handle for easy maneuvering. Holding about .5 kWh, it can start loads up to about 25A. Xantrex also makes smaller units (one backs up my 9-in. desktop color TV) and larger (non-portable) systems that can serve appliances or larger loads (e.g., furnaces with fans).
When it came time to upgrade the house's electrical system (which had a 40-year-old fuse box), I ganged all loads related to the heating system (burner, circulator, thermostats) onto one circuit. We wired in a triple-throw 30A disconnect (which was the smallest I could find to handle 12A) with a plug that allowed me to switch the boiler from utility power to battery power, separately from other loads (see photo).
Total cost for this system (installed by a licensed electrician) was about $800, of which the Xantrex unit was less than $350. Those desiring longer operating time, or having heating systems that draw more power, should consider a larger Xantrex (or similar) unit. While no multihour blackouts have yet truly tested the system, it worked perfectly during several hour-long tests.