Old boiler rooms often are home to steam-heating boilers. Our older cities are loaded with these and lots of people (knuckleheads included) have had decades to mess with what the Dead Men once lovingly installed. So here’s a short list of things to look for when you’re troubleshooting one of those old systems, starting in the boiler room.
The pigtail’s other job is to clog. There’s only one way in and out of this thing. Roiling water is under it and a lot of surface debris is flying up into it. Sooner or later, every pigtail clogs. Your time is too valuable to spend cleaning it, so just replace it. And watch for the common situation where two pressuretrols (one backs up the other) share the same pigtail. Sharing a pigtail was some knucklehead’s way of saving a buck but when that pigtail clogs, both pressuretrols go offline with it.
If the building you’re working in is heating well but you’re not seeing any pressure on the gauge, it could be a clogged pigtail or maybe it’s just an inaccurate gauge. You can buy a gauge that reads in ounces if you want to see what’s going on, but I think it’s easier to just go by the results. If the building is heating on very low pressure, it’s doing what it’s supposed to be doing. So fuggedaboutit and move on.
The steam is coming from it either because the system is running at too high a pressure (flash steam) or the steam traps have failed in the open position (lack of maintenance). It seems easy to plug the steaming vent line but this will pressurize the condensate receiver, which isn’t made or rated to withstand any pressure at all. A receiver tank can explode and seriously hurt or kill anyone standing by. Don’t mess with these things.
Oh, and if you’re not venting the air from the system, which you won’t be if the vent is plugged, you also won’t be able to heat the building, which may be why you’re there.
You know what a P-trap does, right? It keeps gasses from passing. Since air is a gas, it won’t be able to get to that vent on the receiver. So you have no heat in the building? Ask the key question: If I were air, could I get out? Reroute the piping or provide main vents just after the end-of-main traps and watch how much better things get.
The knucklehead installed that one big “master trap” at the inlet to the receiver to keep the steam from escaping. He did this to save the money it would cost to maintain the traps throughout the building. He never stopped to ask, if it were possible to do this, why didn’t the Dead Men who installed the system think to do it? Were they really that dumb? Nope, they didn’t do it because it doesn’t work. Ever.
You should be testing those relief valves to make sure they’re working. Open them when the pressure is low and make sure they close tightly. If they don’t, replace them. Mention to your customers that you’ll be doing this in the interest of safety, and if the valve doesn’t work as it should, you’ll be selling them a new one.
Insulated return lines keep the condensate warmer and that stops Henry’s Law from kicking in. Cooling condensate absorbs carbon dioxide from the boiling process, making the condensate acidic. Insulate the returns and they’ll last longer because the condensate won’t be as nasty.
You can’t make this stuff up.