Old Crown boiler making clunking/popping noise

Blvd

I have an old gas Crown Boiler (Series 10/19/99), Model No. ABF-140SPD, hot water rads) that began making clunking/popping noise — almost sounds like it's popping popcorn. The video makes the sound a bit tinny, but it's clunky, with a lot more solid bass to the noise and it reverberates through the radiator pipes. Have a bad feeling that it's kettling because of build up...and, of course, it's hovering around -6°F Any ideas? https://www.youtube.com/watch?v=H8kQlthkXlU

Alan (California Radiant) Forbes

Kettling, yes, but maybe not from buildup. Maybe it's hard to do, but check to make sure your pump is working. If it's a 3-speed pump, see if you can increase the speed up a notch. If not a 3-speed pump, check the amp draw and make sure it matches what's on the rating plate of the pump.

Also, look to see the setpoint of your aquastat. You probably have to remove the front cover off the front of the boiler.

EdTheHeaterMan

I started hearing a similar noise in a Weil McLain gas boiler and found a load of sludge in the bottom of the boiler. But I didn't find the sludge until the boiler cracked about 4 years later. When we removed the boiler, there was a ton of sludge in the boiler and the piping work. Really flushed the system for days before we commissioned the new boiler. Chemical cleaning and flushing and treatment after the system was flushed the 3rd time. This was a 2 day process to circulate the cleaning agent thru the system and flush the system.

Also added a dirt mag on the return pipe just before the new boiler return opening.

Open the drain valve and see what comes out!

Blvd

Alan (California Radiant) Forbes said:

Kettling, yes, but maybe not from buildup. Maybe it's hard to do, but check to make sure your pump is working. If it's a 3-speed pump, see if you can increase the speed up a notch. If not a 3-speed pump, check the amp draw and make sure it matches what's on the rating plate of the pump. Also, look to see the setpoint of your aquastat. You probably have to remove the front cover off the front of the boiler.

Pump seems to be humming along per usual. Would the setpoint normally need to be adjusted? Nothing has been changed with the system recently.

Blvd

EdTheHeaterMan said:

Open the drain valve and see what comes out!

Yeah, sludge might be hiding from me too. I've drained this system probably 4 times in the last year, water comes out clear. I just did it again right now and the water is clear.

Blvd

Is this issue... dangerous? As in... I shouldn't be running my heat despite it being -6°F outside?

Alan (California Radiant) Forbes

I don't think it's dangerous. Your pressure is right where it should be and you have a relief valve in case of over pressurization.

No, the setpoint should not need to be adjusted. I'd like to see if the sound is still there if you turned down the temperature 5 degrees.

It sounds as though the boiler's heat exchanger is not happy. The transfer of heat to the water is not flowing as it should be and you're hearing the sound of water flashing to steam. Do you have a boiler technician to check it out? I would call on Monday and get on his schedule. Better yet, call him Sunday morning. He might just pick up.

Blvd

Alan (California Radiant) Forbes said:

I don't think it's dangerous. Your pressure is right where it should be and you have a relief valve in case of over pressurization. No, the setpoint should not need to be adjusted. I'd like to see if the sound is still there if you turned down the temperature 5 degrees. It sounds as though the boiler's heat exchanger is not happy. The transfer of heat to the water is not flowing as it should be and you're hearing the sound of water flashing to steam. Do you have a boiler technician to check it out? I would call on Monday and get on his schedule. Better yet, call him Sunday morning. He might just pick up.

We are new to the area, so I’ll have to start the hunt for a tech. I’ll see if adjusting the setpoint will help in the meantime. 

psb75

Much depends on the chemistry of your water. It does sound like 'kettling'. There are many different types of build-up. Some can be loose (like sludge, sand-like, or gravel-like), other types can "bond" to the bottom and sides of the heat exchanger and make a hard solid barrier between the flame and the water i.e. a type of calcification. This happens very often in gas, tank-tyoe waterheaters. A "kettling" sound is the main indicator of this scenario.

Peter_26

I'm curious, if the kettling is severe enough would that cause the pressure to go up dramatically, then air being released if you have automatic air vents? Would that also contribute to more make up water?

Even if it's not severe wouldn't that make the pressure rise anyway? Just curious since I have a hot water boiler that works fine, but has some very faint kettling, though nowhere near what the video sounds like.

HVACNUT

I've used Hercules boiler cleaner and Sludge Hammer with good results.