Since my new wife and I bought our first house about six months ago, I have spent many hours reading Dan's books as well as posts on this forum (interrupted by frequent trips to the basement to trace a pipe or apply a newly-learned concept) trying to understand the steam system we have in our basement. This post was originally intended to ask your help in understanding some things that would help me with a repair/maintenance/optimization strategy. However, I set the post aside for a couple days and in that time a much more urgent problem has arisen. Before I start with that, I will give you an overview of my system.The System
- Two-pipe system that I believe is a Trane vapor system
- New Yorker CGS-A Series boiler circa 1998 rated at 245k input BTUs
- Honewell PA404 additive Pressuretrol (set at near .5 cut-in with an additive 1psi cut-out)
- McDonnell probe-type LWCO
- McDonnell electric solenoid water feeder
- American Radiator Co. tubular radiators with Trane valves and Trane B1 traps
- Main vents and return vent I believe to be Trane float vents (confirmation appreciated)
- The system heats a 2,900 SF house in southeast Michigan built in 1884
I have had three boiler mechanics look the system over and, aside from a lack of documented maintenance, they all have generally had the attitude of "if it works, don't touch it". While, I do not feel the need to spend unnecessary money or time "touching" something for which there is no benefit, I am convinced I have some things that are not quite right that need to be addressed. The first among those was the not infrequent addition of make-up water. I work at home and would hear the solenoid on the water feeder "clunk" several times a week. I scoured everywhere that isn't between plaster and lath and have not been able to find any evidence of any leaks excepting a very small leak around the stem of a radiator valve. And, despite all of this make-up water being added, I have never seen the sight glass more than about two-thirds full.
Reading scores of posts that warned about the dangers of make-up water got me good an paranoid and prompted me to call in the mechanics. To make a long story shorter, I was told to have a blow down performed and that the addition of make-up water was normal. I clarified that the make-up water was being added nearly every day, if not every day, but again was assured it was normal.
It is now about a week after the blow down was done and the boiler now calls for make-up water multiple times during a single firing cycle. Worse yet, it calls for make-up water when the boiler is NOT firing about every 5 minutes - this is not an exaggeration. I figured that the boiler had to be losing water independent of its operation, so I turned it off at the switch (which cut power to the feeder) and waited. Sure enough, I came back in an hour and the sight glass was empty.The Theory
After some head scratching, the process of elimination has guided me to a theory - please forgive me if I get terminology wrong or mix things up. The steam mains combine into one pipe and then go through a concrete floor and under a brick chimney (to complicate things) before it surfaces and ties into the wet return. There is no Hartford loop or anything to prevent water from draining out of the boiler (that I'm aware of) through the wet return piping. My theory is that the section of main/wet return that runs through the concrete floor has some serious corrosion that was potentially knocked loose/dissolved/dislodged by the boil down to make existing holes worse. This would allow water to be lost both during operation and simply through gravity when it is not in operation. Crazy? Is there any way to verify what the problem is?
I have attached some pictures.
Any thoughts, ideas, concerns, etc. are greatly appreciated!