Dan Holohan 2012-12-14 03:42:51
Washington’s axe It’s an old joke. I show you a beat-up old axe and tell you that this is American history. It’s the very axe George Washington used to chop down that cherry tree. Only thing is, the handle’s been replaced six times and the head four times. But it’s the very same axe! Which brings me to Fraunces Tavern located down near the bottom of Manhattan Island. Built in 1719, it is the oldest structure in New York City. That was enough to get my attention. And when the heating contractor asked me to take a look at the heating system, which many hands have touched, I smiled and got on the Long Island Railroad. It was here that George Washington bid farewell to members of the Continental Army at the conclusion of our American Revolution. And before the revolution, it was one of the meeting places of the Sons of Liberty. Throw a stick anywhere inside this building and you’ll hit significant American history, or a chicken pot pie. It’s a wonderful place and as a born and bred New Yorker, I was seeing it for the first time, which was a bit embarrassing. I really should have done this sooner, but then, I still haven’t been to the Statue of Liberty. How to heat NYC’s oldest structure. The thing about Fraunces Tavern is that it’s a lot like George Washington’s axe. Much of the original structure has been replaced over the years, but there’s still enough left to make it delicious. And then there’s the heating system. Untangling history Okay, imagine this antique building that has since been connected to other antique buildings next door, and at some point (probably in the 1930s) some heating company had to install central heat. They chose steam, which isn’t a surprise. But how they got the big boiler, piping and radiation into this dog’s breakfast of construction had me gagging. It made me feel very happy that I am in the writing and teaching end of this business and not in the actual doing end. The basement of this place was more suitable to James Madison (5’4”) than it would have been to George Washington (6’1 ½”) or yours truly (6’2”), but then none of us ever had to install boilers and pipe. Watch your head. At some point a heating contractor got in there and ran piping everywhere. He chose to use cast-iron convectors, connecting some of them with one-pipe steam, and others using two pipes but without steam traps. This is what we call the two-pipe, air-vent system. It acts like one-pipe steam, but the radiators have drains for the condensate. The building needed ventilation so the long-gone contractor hid a steam coil inside ductwork down in the basement. The coil was several inches off the floor, tucked back there in a spot Houdini couldn’t reach. An abandoned control valve sat on the steam line going to the coil, and an abandoned, self-priming pump (operated by a float switch) once sucked condensate from a buried tub and transferred it to a return line, wishing it good luck on its way back to the boiler. This, too, was now just history. The building superintendent was from Russia, spoke little English and had, while in Russia, worked on locomotives. All of which made him perfect for the job of keeping Fraunces Tavern up and running. To get the coil to work, he would open a drain line (which let out the air) and once the steam entered the coil, he would flip the switch for the fan and drain all the condensate into the sewer line. He had no idea why he was doing any of this, other than the system worked when he did and that was good enough. The boiler took on plenty of Fresh water as a result, but that wasn’t a problem because the boiler was soon to leave the building. Creating new memories Which brings me to this part of the story: The building houses not only a museum, but a bar and a restaurant and meeting space as well. Over the years, as tenants came and went, contractors replaced parts of the heating system, taking lots of steam radiators off line, but never considering what this does to the boiler. An oversized steam boiler really knows how to waste fuel. At one point, Fraunces Tavern was host to the visiting Magna Carta, which doesn’t get on well with steam heat. So a high-tech HVAC system was installed in that part of the museum. The rest of the museum, with all its glorious paintings and American artifacts, still has the steam and those rooms are as hot as Beyoncé. Which is why I was there poking around with the heating contractor. The solution for most of the radiators was to use thermostatic radiator valves between the radiator air vents and the radiators. These will shut off the air vents when the rooms reach the temperature set on the individual TRVs. If air can’t get out, steam can’t get in. That will solve the biggest complaint, which was overheating. When a room gets too hot someone opens a window. The TRVs will work the same way on the one-pipe steam radiators and the two-pipe, air-vent radiators. For that steam coil, we prescribed a new control valve operated by an electric thermostat. The stat would have an end switch to start and stop the fan. We’ll also use a float and thermostatic trap after the coil, and drain the condensate into a condensate-transfer pump. By sending the condensate back to the boiler rather than to the sewer, the new boiler will last longer than the old boiler. And the new boiler will be the right size for what’s there now. The contractor measured all the radiation (including the coil) and sized the boiler to that load, with a 1.5 pickup factor for the piping. He then selected the boiler based on the manufacturer’s stated DOE. Heating capacity rather than its net rating. That allows for the extra steam piping that’s still all over the place in this early-American mechanical jungle. Another part of the building has a ductless AC hanging on the wall, and still other parts have electric baseboard. All this along with the steam. And the fireplaces. So many years, so many hands. My favorite part of the day, beside lunch and all that poking around, was realizing that the contractor knew what he probably had to do before I even got there. This guy is sharp. He just wanted someone else to look with him, think it through and hopefully say he was right. He also wanted to share the wonder of this place. And in that way, he was like a schoolboy. As was I. Dan Holohan operates HeatingHelp.com. You can reach him at firstname.lastname@example.org. He loves hearing from you!
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