Hoping you folks can help. Long story, but please bear with me…
Been in an old house with oil-fired, single-pipe steam heating system for 10 years. System always serviced regularly by our oil company. It’s a drafty old place, but system always seemed adequate for the most part.
That was until a year or so ago when I noticed the water level was over the top of the sight gauge. Service guy examined system and suspected the automatic water feed was not closing off completely. He drained off some water to normal level and put some stuff into the boiler that turned the water green; said it was a chemical to help loosen any residue, etc. that might be hanging the feeder up.
Problem persisted. I was keeping an eye on the water level and periodically would see it overflow the boiler again. Service guy said it looked like I’d need to replace the automatic water feed but, rather than do it now in the middle of winter when they were busy, he’d just disconnect it and close the valves on either side. He said if I saw the water level go down any significant amount, I should open the manual bypass valve to add a little. I asked him if that was OK to do while the system was hot and he said that’s what the automatic feeder did.
So I did as he suggested to limp through the winter. But the water level was erratic. Sometimes it would be low, so I’d add a little; but other times it would actually be over full and I’d have to drain some off again. The service guy said it was likely the old-style gate valves in that water feed manifold were leaking and the whole thing should be replaced along with the automatic water feed.
I got through the winter and shut the heat off for the season. Mid-summer, I find the boiler leaking. A check of the overflow valve, attached piping, etc. showed no leaks – it was coming from the boiler itself. I removed the covers and it was clear it was leaking in several spots. Service said I’d need a new boiler. This seemed odd as it was only about 17 years old, but they said that was not unusual. Looking back, I suspect I cracked the boiler by listening to them and adding water to a hot boiler. Either that or the frequent additions promoted just enough corrosion to do-in an already compromised boiler (we’re on well water, which I know can be hard on a system, even though we do have a softener).
Between their lackluster attitude, the high price they quoted me for replacement and my general lack of confidence in them, I went to another company that had more experience with steam systems.
They installed the new boiler, including all new low-water cutoff and automatic water feed, valves and manifold. They also changed a number of radiator and main line vent valves. It wasn’t yet heating season, but I ran it periodically at their suggestion to check for any issues and they skimmed it a couple of times to get any crud out of the system. All seemed normal until one evening when I had just turned on the system, I noticed the water level was above the sight glass. Worse, I found two radiators spraying water out of their air valves. Thankfully I was there to catch them before the flooding got too bad and we had a real disaster. I shut off the system and called the installer back in.
The odd thing was the way just those two radiators had filled up. There are three main branches of the steam system once it leaves the boiler, each of which serves radiators in different portions of the house. The two that had overflowed were on the branch for the front of the house. That branch has three legs coming off it: one feeds a single first-floor radiator, a second runs up to feed two second-floor radiators and the third feeds a first-floor radiator and a second floor radiator. It was these last two that had overflowed – yes, one on the first floor and one on the second.
I thought there must be a blockage in that leg that allowed steam through, but slowed the condensed water from flowing back, thereby filling up the pipes/radiators of that leg over time until they overflowed. In the meantime, the boiler water level wouldn’t be replenished, so the automatic feeder would add more. Then, when the system was shut off and the water in the pipes had time to seep back down, the boiler would be over-full again. This was consistent with what I was seeing.
My installer said that was unlikely. He had never heard of a blockage in the actual steam line and that any blockages usually occurred in the return line, since it was the lowest point of the system. I pointed out, though, that the return line was down in the basement. If it had plugged, all three of the legs off that branch would have filled with water and the other first-floor radiator would have been spitting water before that second-floor one did.
But he felt that wasn’t necessarily so; that it could have to do with the orientation of the piping, etc. So he removed the return line, expecting to find it clogged. It wasn’t. He also flushed and skimmed the whole system again just in case there might be some remaining crud clogging things up. I’m again running it periodically while keeping a close eye on that water level and those two radiators that had leaked, but I have no trust in this system at this point. We’re heading into cold weather and I can’t be confident to leave the house with the heat on for fear of coming back to a flood.
Do you think it’s possible that the actual steam line for the leg that serves those radiators could be plugged? If so, can it simply be snaked out in some way? Any other possibilities? Many thanks in advance.