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boiler debugging
Tuesday, November 25 2008
Tomorrow Gretchen and I would be driving down to Maryland for another vegan Thanksgiving at her parents' house, so I'd set aside much of today to attend to pre-departure chores: mostly cleaning the house and firing up the boiler for the first time this season. But it was that second item on my list that ended up devouring my time today. The boiler usually starts, albeit reluctantly, after eight months of being idle. Today, though, it ran only for a few seconds before dying. Hmm, what could be wrong? Though I'm unusually fearless when it comes to maintaining machines, I have only a vague understanding of how boilers work. Somehow oil is mixed with pressurized air and sprayed into a chamber, a spark ignites the combination, and the resulting fire heats water in the voids around the chamber. Something must have been happening to block the oil, the air, or the spark.
The easiest thing to do was to replace the fuel oil filter, something I've done before. Eventually such filters get gummed up, and the old one had been there for three or four years. So I drove out to Herzog's and bought a replacement filter, one different enough from the old one that I had to break and remake its plumbing connections.
But even with the new filter, the boiler refused to start. So the next thing I tried was cleaning the nozzle that shoots oil and air into the combustion chamber. I attempted getting to that nozzle using an observation port, but this proved impossible, so I unbolted the fan/oil pump apparatus from the front of the boiler and pulled the whole sorry mess off. The nozzle (and surrounding fins that looked as if they'd been designed to impart a cyclonic spin to the air) was filthy, so I cleaned it with paint thinner.
Still the boiler wouldn't start. This forced me into a series of component-level tests familiar to any computer programmer. I disconnected the plumbing to and from an oil valve, which seemed to have trouble staying open. So I removed it from the boiler and took it upstairs to test in my laboratory. There I energized it with 120 volts while blowing air through it with a hose held in my lips. It worked flawlessly. Later, after I'd reattached it to the boiler, I saw that the problem was upstream from that valve. The pump could produce a short burst of oil initially, but it couldn't maintain the supply (a problem for which the valve was blameless). Either the pump was defective or the supply line was jammed. Disassembling the line upstream from the pump led to such a frightening deluge of fuel oil that the only possibility left for defective components was the fuel pump. So I ordered on online.
This meant the boiler wouldn't be fixed before we'd be leaving, so the house would be unheated during our absence. The weather was predicted to swing between 27 and 40 degrees Fahrenheit during that time, not cold enough to freeze the pipes, but there would also be cats living in the house. So I decided to set up a few heating stations powered by electricity. One would be an oil-filled electric radiator in the living room. Another would be a fan-driven space heater in the upstairs bedroom (its thermostat set to 60 degrees) and finally there would be a heating pad for Wilma on the living room ottoman. I'd also set up a webcam pointed at a thermometer so I could check in from the road and allay my own fears.
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