1-pipe system rapidly cycling boiler level down (sight glass), after sodium nitrate tablets...

BobbyOrr4

Hi Heating Help!- I have a residential 1-pipe steam boiler system, with a Burnham V33. I recently, for the 1st time, added some Rectorseal Steammaster tablets (about 10), with the goal of passivating the system against corrosion. The system started quickly running the boiler level down, so that the sight glass goes empty and the low-water switch shuts the burner off. The system is not leaking; once the burner is off, the water level quickly returns to full on the sight glass (quickly = approx 1 minute). We are getting quite a bit more gas (of some kind) coming from the steam traps on the radiators, than we used to. Also, I can hear condensate running back down through the return lines (sounds almost like someone flushed a toilet) I believe the flow rate is much higher than before because the condensate return noise was never audible before.

The pressuretrol is set at 0.5 cut in, and cut out 1 psi above that.

Any ideas? My first suspicion is that air got into the system, when I opened a port on the boiler to put the tablets in. However, not sure that makes sense, as there must have been some air in there anyway; I doubt this old system would hold a vacuum. I did find the main steam vents, one on each of the two main lines, quite near the boiler. I did not hear any gas escaping from them; they probably have not been looked at for a long time, as they are above a fire panel installed at least 20 years ago.

Thank you for any comments.

Fred

Your problem is the Steamaster tablets! The instructions on the bottle are WRONG. Drain the boiler and refill it. Use just one tablet.

nicholas bonham-carter

At least with such a heavy dose, you will have cleaned out some of the sludge which may have accumulated there!
Drain and refill with fresh water, and reboil. When you are satisfied that the boiling characteristics have returned to normal, then add one tablet only. It may take a couple of refills to get all the steamaster out.—NBC

BobbyOrr4

Many thanks, Fred and Nicholas! I did not know about the many comments here regarding Rectorseal's dosage recommendations being high, and the issues that can result if that dosage is used. Thank you for setting me straight.

The issues other posters described (even a Youtube!) sound quite similar to what I observed. So will let system cool, drain & refill, adding 1 tablet.

ChrisJ

Personally I run 2 tablets, but I think it depends on the system, the quantity of water in the boiler and the quality of the water.

Any more than 2 and I run into issues.

The good news is a strong dose is often intentionally used to clean the system out. So, you did that.