Is My One-Pipe Steam System Working Properly?

MichaelG

I bought my first house this year in Baltimore, and it has a one-pipe steam heating system. I read a couple of Dan's books, had Frank the Steamhead over for a visit, and I've been doing my best to follow all sorts of wisdom to get the system up and running efficiently (and cheaply). I added Gorton D vents to the ends of both mains, and installed 1.5" of fiberglass insulation to the mains and near boiler piping as well. This weekend was the first time I finally started up the boiler, and I'd like to describe the operation of the system to those of you with experience, so you can tell me if things seem like they're running well.

I'm going to be lazy and skip drawing a schematic of the system, and instead will do my best to describe it instead. The boiler is an oil-fired Columbia CFSH from about ten years ago, about 115KBTU. The house is a 2500 sq ft rowhouse, three floors, built in 1914. Above the boiler, one parallel-flow main (2") heads 25 feet to the front of the house, serving four rads on three floors. Another parallel-flow main (2") heads about 5 feet towards the back of the house, where a branch heads up to two rads, there's a drip, and the main continues on uphill as a 1.5" counterflow main, for another 20 feet to two big rads at the back of the house. As I stated earlier, I added a Gorton D on a long nipple in about 12" from the end of both mains. I planned to use a bigger main vent, but Frank the Steamhead wisely recommended that I go smaller to avoid moving steam too fast in the counterflow main, leading to condensate suspension. I put a Gorton D in the parallel-flow main to keep things balanced. The mains are well insulated now, and all the sloping looks right.

The boiler kicks on and essentially nothing happens in the entire system for about 15 minutes. At that point, I start to see the water in the sight glass begin bobbing up and down, not violently but constantly and rhythmically. Is this normal or a sign of dirty boiler water?

Since I have the mains so well insulated, I can't really feel the heat moving through them, but I can tell the instant steam arrives at the main vents - not because of a noise, but because they go from stone cold to super hot in an instant. This takes place at both main vents about the same time, around 20 minutes after the boiler turned on. Does this seem like an excessive amount of time?

I wander through the house and feel each radiator, and they all get hot more or less at the same time. Heat creeps across them one section at a time, and about 45 minutes after the boiler first turned on, all the radiators are fully hot. Very hot! Does this seem like an excessive amount of time?

Exactly 65 minutes after the boiler first turned off, it turns off due to pressure. By the way, the pressuretrol is set at 0.5psi cut-in with a 1.0psi differential. In the case of this morning, I was going from 66 degrees to a set point of 71 degrees. It took the first hour of constant running, along with an additional hour of intermittent on and off cycling due to pressure, to reach that point. Does this sound right?

Overall, I can't really complain since the house heated up nicely with no water hammer. It seemed to take a while to get there though. Also, the varivalves I have installed on all the rads gurgle quite a bit at times, and drip some water too. Looking at the boiler water through the sight glass, it looks like there are a lot of suspended solids, probably rust. I read that having clean boiler water is important to having dry steam. I'm not sure the best way to get it though. Will frequent blow-offs solve that problem? Do I need to skim the boiler water? How do I do that?

Thanks for reading and I appreciate your advice!

Steamhead

Now you need to have us service the boiler- or switch it to gas, your choice. Once that's done it will heat faster and use less fuel.

Mark N

No heating can take place in a steam system until you make steam. If yesterday was the first time the boiler ran the boiler, the water, and the pipes are stone cold. Takes quite a bit of time to bring things up to steam temp. Gets much better when it starts running regularly with the cold weather. You're lucky to have Steamhead available to service your boiler. Buy a copy of "We Got Steam Heat" and give it a read.

David Nadle

The timing doesn't sound too bad considering a 5 degree makeup. Try keeping a constant setpoint for a while and see how things perform. The waterline bouncing is a matter of magnitude. A half-inch is fine, 2 inches is not so good. You're lucky to have Steamhead in the area.