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HVAC/ HYDRONICS T his is to continue our series on steam. In this article I'm going to bring back some much asked for friends from our archives to tell the story again. So here's Bruce and Bubba from B&B Mechanical to give you the "real deal." Recently one of "Friendly Oil's" customers had a boiler replaced. The installers put in a new steam boiler, adjusted all the controls, did a combustion test and then left. In the next three days they got seven service calls for erratic and insufficient heat. After several of the oil company burnermen (hmmm), walk in, find the unit hot, the burner capable of running and what appears to be nothing wrong—the service manager gets steamed! In desperation, the service manager of Friendly's decides to get another opinion, and so he calls his old buddy Bruce. Bruce is very busy with a commercial burner problem and he decides to send one of his techs. But, this is not just another burnerman walking in—unh unh— it's Bubba, and boy has he learned a lot since we first met him (1994). He now knows that Lanthier's Second Rule of burner service is "assume nothing," and that the first rule is "listen to the customer." After he arrives and goes in, here's what happens. "Hi there, I guess you're having a problem with your new boiler?" asks Bubba. "A problem, oh yeah, we're having a problem all right," said the customer, Mrs. Nastybear. "We spend $5,000 for a new boiler, and it works best when the burner is off, and now they send another guy!" "When the burner is off?" questions Bubba. "Please explain what you mean." Wow, now there's the first change, thinks Mrs. Nastybear. He doesn't just want to go down into the basement. She tells Bubba, "Okay, here is what happens. We have a clock thermostat because we both work, like it cool at night and we're trying to save money. After the heater has been off for a while and it first warms up, it heats real fast and the radiators start to get hot. Then the radiators don't get any warmer, and the burner keeps running. Then the burner shuts off, and then just when the radiators start to warm up again, the burner comes on and the radiators don't get any hotter. Just like I said, it's better with the burner off." "I think I know what to do," said Bubba. "Let me have a look at it." After being in the basement for some time, Bubba comes up and announces to Mrs. Nastybear that he has replaced a control, made some adjustments and now feels the problem is fixed. Do you know what control Bubba changed, and what adjustments he made? And why did the radiators act in this peculiar way? Well, here's the story he gave Bruce, so let's see what happened. "I arrived on the job Uncle Bruce, listened to the customer tell her story and replaced the pressure control," he said. "It was running way over three pounds before it shut off, and I couldn't get it to run the burner the way you showed me. I put on a vapor type control, and set it to shut off (cut-out/ Main) the burner at 16 ounces and to cut the burner back in (cut-in) at four ounces. The radiators got nice and hot, and the customer seemed happy," explained Bubba. "Well, I'm glad you remembered what I told you about pressures, and did all of the air vents work?" asked Bruce. "Boy, I think so," replied Bubba. "Because you told me that at one and one-half psi those #1 vents are supposed to close, and all of them did, they wouldn't let any more air out, and so no more steam came in, just like she said, 'it worked better when the burner was off." "Well I guess I better call Friendly's and tell them the news, and then bill them for the call and the control," said Bruce. "They will have a fit over the price of that vapor con- trol, but if they had put one on with the boiler, they could have saved themselves eight service calls, oh well." Did you figure this one out for yourself? Remember these impor- tant facts: 1) The #1 air vent, or its equivalent, Figure 1, were designed to operate at a maximum of one and one half psi, and if you go over that they do their job and shut down. 2) Normal pressure con- trols, PA404, have minimum operating ranges of 0.5 psi to 1.5 psi and may not be sen- sitive enough to work with many systems. The PA404 is an old control from the days of coal stokers and large water content boilers. In addition, its diaphragm, Steam - Part 4 By GeorGe Lanthier Figure 1 42 FEBRUARY 2015 | FUEL OIL NEWS | www.fueloilnews.com