The home heating oil industry has a long and proud history, and Fuel Oil News has been there supporting it since 1935. It is an industry that has faced many challenges during that time. In its 77th year, Fuel Oil News is doing more than just holding
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www.fueloilnews.com | FUEL OIL NEWS | JULY 2014 43 with either strips or a device like that shown in Figure 6 that is available on our website. If you do feel surging may be the reason for the flooding, maybe you need to use something I've come to call 'The Boston Trick.' Although this can be used for troubleshooting, I've also left many on jobs as a safe guard. In Figure 7 we show a #11 switch that is used in many McDonnell & Miller low-water cutoffs. M&M recommends that power come in on terminal #2 and go to the burner on terminal #1 and the load wire to the feeder be wired to ter- minal #4, Figure 8. A jumper should be placed between terminals #2 and #3 to provide power to the feeder. The #11 switch is actually a three-position switch. With the proper amount of water in the boiler the switch is closed between terminals #1 and #2, Figure 9-A, allowing the burner to run and the feeder shut off. As the water level drops terminals #2 and #1 remain powered and now power flows from #2 to #3 and makes terminal #4, Figure 9-B. If the feeder is not present or fails to fill the boiler the switch between terminals #2 and #1 opens shutting off the burner, and terminals #3 and #4 remain closed energizing the feeder, Figure 9-C. Now, the problems and solution. Did you know the average four section steam boiler currently holds about nine to 14 gallons to the working water line? Did you know that at 55 pounds per square inch of water pressure you can flow about 10 gal- lons of water per minute through a ½ inch pipe? That means that a gallon of water can be fed into that boiler in about six seconds, and that's not a long time. What happens if a wet return fails? Or a boiler fails, or any other leak? Well at 10 gpm you can put a lot of water on the floor in no time at all. So, years ago I was taught this great trick, and I've gone on to teach it to thousands. Between terminals #2 and #3 put in a thermal fuse. That thermal fuse is nothing but a bare #18 AWG thermostat wire and it also fits in that 'dog bone' space nicely. The #18 bare wire can only carry between three to six amps. With both the burner and feeder running, your amperage draw is about three to six amps, so within a short time the amperage draw will burn out the wire. Essentially, you have a thermal link or fuse! That fuse will fail in about 30 to 40 seconds and instead of a flooded boiler or basement you only have between five or six gallons to mop up. That pretty much covers all the reasons for a flooded steam boiler other than the customer overfilling it. We'll be showing up here at Fuel Oil News on a more frequent basis again and so maybe we'll look at what makes water boilers flood down the road. By the way and if you haven't heard although Firedragon is no longer involved with teaching any oilburner codes including the Massachusetts Oilburner Code. We will be bringing you Code updates on both 527CMR4.00 and NFPA31 as they happen, and if you missed our last update get in touch with us. See ya! *George Lanthier is the owner of Firedragon Academy, a Massachusetts Certified School teaching both gas and oil heating subjects along with heat- ing system design, management and troubleshooting topics. Firedragon is also a publishing firm for George's over 60 books and manuals on HVAC subjects. He is a CETP, NATE, NORA, PMAA and PMEF Proctor and a Massachusetts Certified Instructor. He can be reached at 608 Moose Hill Road, Leicester, MA 01524. His phone is 508-421-3490 and his website can be found at www.FiredragonEnt.com By GeorGe Lanthier* HVAC/ HydroniCs l F o n Figure 5 Figure 6 Figure 7 Figure 8 Figure 9