Invisible leak, help please!

Glenwood21

Hi all,

I live in an old 1900s house in Brooklyn that we moved into about three years ago. This is a three-story house with a one-pipe steam system.

When we moved in, we replaced the steam boiler. We sized the boiler correctly, and I double-checked this with "The Lost Art of Steam Heating" again today, measuring all radiators. It's about 100,000 net Btuh.

I've changed all the vents, and the system is balanced: no high pressure; it doesn't exceed 1 PSI, even on long runs. It's not short-cycling, overfired, or underfired. I've checked all the pressure and gas inputs, and insulated all the visible pipes with rockwool so there's no heat loss.

However, I lose about a gallon of water daily when the temperature is around 32 degrees outside.

I've pushed the system on a long run and used a thermal camera to check behind the walls for any temperature increase around the risers or returns behind walls, but I don't see anything.

So, it's still a fairly new boiler with no leaks or white smoke up the chimney. The vents are new, the valves don't seem to be leaking and have no high pressure, and the risers and returns behind thewalls do not seem to leak when checked with a thermal camera. I need to find out where the leak is coming from.

There's always a water feeder solution, but at that rate of water loss, I will break the boiler in one or two more seasons… One gallon of water seems to much to be a steam leak…

If I want to try pouring water down the lines to test returns, how should I do this? Should I empty the boiler, open the purge valve, and pour water into the vents?

If anyone has another idea of where the leak could be, please let me know. I need help!

Thanks

EdTheHeaterMan

To find a water leak or a steam leak you need to think like water. If i was water and wanted to leave this system where would I go?

Was the new boiler pressure tested before commissioned? You may have a steam leak between the boiler sections. that is tested by overfilling the boile to about 18 to 24 inches above the water line. If there is a steam leak it will show up as a water leak when the water is that high. You may need to remove some of the covers and insulation from the sections.

Another popular leak is a return pipe that goes below the floor before it comes back up to connect to the boiler. I remember installing a boiler in a church that has a rotted out dry return the went thru a crawlspace before it got the the basement. the pipe was under about 6" of sand and was unable to be seen. After the new boiler was commissioned, the water feeder was one with a water meter. After one month of operation, the feeder registered 999 on the meter and shut off the boiler. By resettingthe 999 to 000 the boiler started right up. now I needed to find where 999 gallons of water went in a month. That is when I found the rotted away return, and it was rotted for some time… more that 5 years at least.

Replace the return pipe and WOW did the fuel bill go down. (the church's board members thought the new boiler was the reason for the savings… I didn't have the heart to tell then is was anything else. New boiler was money well spent.

Long Beach Ed

After doing what Ed says, I plug all the vents with 1/8" threaded plugs and pressurize the system to about 15 pounds of air with a pump. Any leaks whistle. I usually find the radiator valve stems leaking, a few unions leaking along with the sight glass unions. Combined together, these can consume a gallon of water on a large system. The work usually takes about an hour and leaves us with a tight system.

Glenwood21

Thanks. I didn't realize steam leaks could lead to a gallon of water at such low pressure. I bought some packing for the valve stems, but doing this on 13 radiators is a bit of a drag… We have access to the basement, and I know no returns are in the ground—it's all in the basement ceiling. It probably makes sense to try with air pressure first, but I'll need someone to do this.

Jamie Hall

One lonesome drip somewhere every 10 seconds is a gallon of water per day…

Larry Weingarten

Hi, This is completely irrelevant, but @Jamie Hall , I think you've got a bestselling book title! One Lonesome Drip 🥳

Yours, Larry