Steam Boiler - Loud Humming/horn noise coming directly from Boiler (See Video)

Sleblanc

Hi,

I am having an issue with my one pipe steam boiler system. The unit is giving off a very loud humming noise roughly every 10 seconds when the unit is cooling back down.

Something to note, as you will see in the second video is, when I went to drain the system and add new water, it sounded like the boiler was full of air.

Humming Noise: https://youtu.be/lEIXKmOmf1w

Draining System - Sounds like air in boiler?: https://youtu.be/qte3Yu7B0xg


Any ideas into what might be causing this... or any possible solutions are greatly appreciate.

Boiler Info:
Crown Boiler
Series No: CROWNB00644100
Year: 2018(Installed)
Low Pressure Boiler

Ironman

There will always be air in the system once the burner stops and the vents begin to open back up until it begins to make steam again.

It sounds like your  main vent(s) are not functioning or sized properly.

What’s the pressuretrol set at?

Sleblanc

Hi, Thank you for your response. When you say main vent(s) are you referring to the vent on each radiator?

The pressuretrol(honeywell) is set at: DIFF= .5 PSI / Main = 1.5ish PSI.

ethicalpaul

No, he's referring to a large vent on each of your steam "mains" in the basement. You typically find it after the last radiator supply pipe possibly near the point where the main turns vertical and drops to the wet return.

It's possible you don't have any, which is a problem you can have fixed.

Were your videos immediately following a call for heat? Maybe you still had the vacuum from collapsing steam.

In the second video it could be that it was sucking air into the boiler to relieve the vacuum then the water was free to drain. It might be easier to see what is happening without that kinked hose on there.

I have no idea what is causing that air horn sound. In the first video it happened without you touching the boiler?

Sleblanc

Thank you for your response. Yes, these videos were taken directly after heating the home and the unit was cooling down. This hummer noise had happened for the first time about 2 weeks ago. I had flushed the system which stopped the humming. Unfortunately the humming noise is now back again today. I flushed the system again and i am hoping this resolves the issue again.

I am realizing that since the humming came back, flushing the system is only a temporary solution. I would like to get to the bottom of it and have it corrected for good.

ethicalpaul

Do you have a radiator vent that you can easily remove? (sometimes they are pretty frozen in place is why I ask).

You could remove a vent immediately at the end of a call for heat (you can force the calls for heat by manipulating the thermostat of course), and see if the sound fails to occur. You'd expect to hear a whooshing intake of air into the radiator, relieving the vacuum, instead of whatever is making the horn sound.

Can you tell what is making the sound? Does it happen after every call for heat, or maybe just after long ones like when it's recovering from a temperature setback?