Boiler Kettling

Old 11-22-17, 07:39 AM
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Boiler Kettling

A common topic here on the forum - boiler noise. I thought it was air noise waking me up at night upstairs, at the high point of the system next to my bed. But with investigation I believe the boiler is kettling and the sound is reverberating through the system. I'll post my facts first:

1 - The sound is loudest at the boiler itself, and occurs only when the burners are firing. If the burners turn off, but the circ is still running, it quickly becomes silent.
2 - The noise does not begin right when the burners fire, but does start well before peak temperatures (noise @ ~160 on the aquastat)
3 - The system was recently drained by a professional who added a check valve for me. It did not kettle (to my knowledge) before this drain and refill.
4 - I rarely hear any air noise in the system.
5 - My boiler is well oversized, based on measured BTUs of my slant fin rads throughout the house.
6 - I have two zones each with their own circ, but it kettles whether one/either/both circ pumps are running.

A good mix of potential causes here, and likely a large mix of potential solutions. First and foremost, is this an emergency situation (Thanksgiving being tomorrow)? What would the experts here recommend first? Turn down aquastat? Add in treatment fluid? Thanks in advance!
Old 11-22-17, 08:26 AM
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Could be air hitting one of the flow controls . This will make a clink clink kind of sound if thats what you are hearing..

If he opened the system it may take time to get the air out. It depends on if the air vents are working and position of them..

Pics help..

Pressure can be raise some to help eliminate if this is indeed the issue..
Old 11-22-17, 08:26 PM
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Pics & Videos

The noise is louder from the heat exchangers themselves; the flow control devices are a few feet away and not making any sound I can tell. I have a video of the noise (only 1 MB) but don't see a way to upload it to the site. Are there any file sharing sites you would recommend? Trial one, I've turned down the aquastat. It was set near 200, but I wrapped black electrical tape around the supply line and was reading 205+ with an IR gun. Too close to steam for me. I've dropped the aquastat to 180 and it's still reading 199 on the supply. Is it possible the aquastat is off by 15+? Or any better ways to measure actual water temperature? At this point I trust neither the visible gauge nor the aquastat.

The first photo shows the new setting, about 185 for the limit off, and the limit stop at 200. The second photo shows the original setting, both limit off and limit stop at 200.

No need to reply; it's Thanksgiving! have a great weekend and thanks for the help.
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