Boiler making kettling noise

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Old 02-12-17, 02:12 PM
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Boiler making kettling noise

My homeís boiler has recently started making a lot of noise. It sounds like pebbles are crashing around inside when the boiler is running. When the boiler turns off (but the circulator pump is still running), the crashing subsides within a few seconds.

Recent history: I opened up the system over the summer to make some changes. (I was installing a hardwood floor, so it seemed like a good time to make some changes to the pipes.) I refilled and purged the system after that, but I suspect that air was left in the system for several months before the heating season began. Even though I thought I had completely purged, when the boiler started running the fall I noticed gurgling sounds. The gurgling air sounds have gone away, replaced by the crashing pebbles.

In addition to the pebble noise, I have two shutoff valves and three drain cocks that are leaking. So although Iím reluctant to open up the system again for fear of introducing new oxygen and making things worse, Iím thinking that given the number of things that need fixing, itís probably worth it.

Regarding the shutoff valves and drain cocks, I think I know what I want to do. The drain cocks just screw in, so I can replace those easily. The shutoff valves are soldered in. I can sweat pipe, but Iím actually inclined to replace them with Sharkbite valves, since those would be easier to replace in the future if they start leaking.

So I think Iím all set with those changes. What I want help with is the crashing pebbles sound. Let me provide some more information about my system:



Itís a Burnham boiler that was installed in 1988. Info about the boiler model is written on the wall inside the boiler closet:



I realize 1988 is pretty old and Iíll have to replace the boiler at some point. On the other hand, Iíve heard that these old Burnhams can run virtually forever if properly maintained, and Iíd like to keep it running as long as possible.

I found these articles outlining possible causes of kettling:

What a Boiler Kettling Noise Means | DoItYourself.com
https://www.sentinelprotects.com/uk/...p-boiler-noise

One possibility is that the water is getting too hot, due to a variety of causes: faulty aquastat, failing circulator pump (leaving water in the boiler too long), or pressure too low.

But when the boiler shuts off, the gauge on the boiler reads 25 psi and 190 degrees, which seems reasonable:



This site has a nice table showing the boiling point of water vs. pressure: Water - Pressure and Boiling Points

At 25 psi, the boiling point of water is 240, so it seems like I have a significant buffer between 190 and 240.

Given that the temperature seems OK, buildup of mineral deposits on the heat exchanger (causing localized boiling) seems the most likely cause. We have hard water, resulting in significant mineral deposits on faucets, for example, and on valves and pipes in the boiler system:




From my reading, it seems like I should try adding an inhibitor to dissipate buildup and reduce future buildup. Fernox F1 seems to be the most commonly recommended:

Protector F1
https://www.amazon.co.uk/Fernox-5659.../dp/B003HQ97E4

Does this seem like the right thing to do? Inhibitor seems to be commonly used in the UK, but not so common in the US, and I canít quite figure out why.

Thanks for any help!
 
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Old 02-12-17, 02:43 PM
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Post approved... You need 6 posts or so to have posts with pics show up without moderator assistance..

Welcome..

Let me read over your thread and see if I can help..
 
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Old 02-12-17, 02:52 PM
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Lower the temp in the aquastat to 180F. Possible set it so the burner kicks off at 175f.. youll have a little soak time so temp will/may rise abit as it does now..

As far as cleaner, its worth a shot. I put it in my 50+ year old boiler.. But I use this stuff for most of my cast iron boiler tune ups..

1 qt. Boiler and Heating System Cleaner-35206 - The Home Depot

While you have the system open to fix the valves, remove expansion tank and add 12 psi - 15 psi of air to it.

Change all air vents that are on the system for preventative maintenance..

That pipe coming from the ceiling looks troublesome... A leak somewhere.. That should be addressed..
 
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Old 02-12-17, 04:45 PM
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What comes to my mind when you mention "kettling noise" is the rattling that I experienced when air bubbles leaving my boiler encountered the flap inside my Taco 220 Flo-Chek Valve.

The Flo-Chek is intended to quietly prevent convection from flowing through to the baseboard when there is no call for heat; but when bubbles are present in the baseboard fluid, it makes (made) lots of noise.

Purging the air from the system eliminated that kettling sound (which occurred only while the circulator was running).
 
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Old 02-12-17, 08:28 PM
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Thanks so much for the detailed reply!

I wasn't sure how concerned to be about that pipe coming from the ceiling. I guess I should cut some drywall and get a look at what's going on. That pipe is the hot water pipe coming out of the water heater (which is in the closet adjacent to the boiler).

Thanks for the recommendation on the boiler cleaner. Probably similar to the Fernox brand that they sell in the UK. It's good to know that there's one available in the US, and that you've had a positive experience with it.

Good idea to repressurize the expansion tank. When I moved into the house five years ago, the pressure release valve was letting out water every time the boiler ran. The previous owners thought it was normal. I replaced the expansion tank and solved that problem. So the tank is relatively new, but as long as I'm doing everything else, I might as well add some pressure to it.

The air vent is new as of last summer when I opened up the system to do the previous work. I'm pretty sure the previous vent wasn't working.

I know next to nothing about how to operate the aquastat, and I'd really like to learn. Part of my problem is that the aquastat is on the side of the boiler, right up against the wall, so it's difficult to access:


At least there's that mirror there, so I can get a little bit of a look at what's inside the aquastat:


If I just get a photo from the side, I can't see much:


The inside of the aquastat cover has some information:


Any advice on how to set the temperature would be very much appreciated. I would really like to learn how to operate this part of the system.

Thanks again for taking the time to provide such helpful advice!!
 
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Old 02-12-17, 08:58 PM
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There is a wheel on the part where the blue and red wires are that adjust the high limit boiler temp.

That control you have is a high limit only control with a nonadjustable differential. All you do is set the wheel where you want your boiler to shut down and the control will do the rest.

Hope this helps a little.
 
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Old 02-13-17, 07:25 AM
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Spott, thanks for the guidance on locating the wheel for setting the aquastat. No wonder I never found that -- it's back in the corner of the closet where I can't see it. But I did manage to get a camera back in there to figure out what I was doing. It was set to 180, so I lowered it to the minimum setting where the wheel stops turning. This appears to be about 175. Here's how it looks currently:

 
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Old 02-13-17, 08:53 AM
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D,
That's fine as long as you get enough temp going through the emitters to heat your house. You can adjust it as necessary. Keep in mind this has an 8 deg nonadjustable differential built in which means if you have this set at 175 your the boiler temp will drop to 167 before the boiler fires again. If you find it takes a little longer to heat the house you can always turn it up a little.
 
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Old 02-13-17, 09:45 AM
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The deposits on the exterior of the pipe and valve are due to leaks that must be fixed. Adding an inhibitor or system cleaner won't help that.

Hot-water heating systems should be closed systems. If there are no leaks and no addition of make-up water and there is a suitable air removal device, no inhibitor should be required.
 
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Old 02-13-17, 01:12 PM
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I cut the drywall around the pipe coming out of the ceiling that has mineral deposits around it. That pipe is the main pipe coming out of the water heater, supplying hot water to the house (and not part of the boiler system). The leak appears to be at the bottom of a T:


There's no moisture that I can feel, but there's obviously been a leak in the past.

The mineral deposits are most significant on the back side of the pipe:


There are two pipes running above this one, but no indication that those have leaked:


If this pipe was part of the boiler system, I'd sweat in a new T as part of my fixes to the boiler. But since it's part of the hot water piping and it's not currently leaking, I'm not inclined to do anything. I'll leave the hole in the ceiling open so I can monitor. Does that seem like a reasonable approach to this particular problem, or is it more important to fix than I'm thinking?
 
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Old 02-16-17, 02:35 PM
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Originally Posted by discman017
". . . it's not currently leaking . . ."
I think it is still leaking; but it's very slow, and because it's a "hot" water pipe, the water component evaporates leaving behind all of the minerals that were suspended in the water.
 
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Old 02-18-17, 08:35 AM
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Vermont, thanks for that clarification. Makes sense that it's leaking and evaporating. I hadn't thought of that. I think I'll go ahead and fix it then.

What's the right way to go about this?

Do I just try to clean and then add more flux and solder around the joint that's leaking (the bottom of the T)? Is there any point in trying that, or is that bound to fail? Should I instead desolder that joint, and flux and solder it more completely (fluxing the inside of the joint rather than just the edge)? Or do I need to cut the whole thing out and solder a new piece in?

Do I just try these in order and see what works? Or should I just jump straight to cutting out the T and some of the pipe on each side, and then constructing a new piece (T plus some additional pipe to replace the cut-out pipe, and three sleeves to join it to the three pipes)?

Thanks for all the help!
 
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Old 02-18-17, 09:36 AM
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I'm just a Real Estate Broker, so my experience in sweating joints (and re-sweating joints) is really limited to pretty much my own personal projects . . . . and commenting freely on the work of others; but I can be fairly certain that when it comes to leaks like yours, you have to take it apart and freshen up the copper, re-flux, and start from scratch making a new joint.

I've tried in vain to seal joints that weren't quite sealed and leaked under pressure; but I've never succeeded (and if I ever had, that would be a good thing to remember!). It's frustrating to re-do anything; but trying to re-seal a joint that has already cooled, and has water inside that turns to steam when new heat is applied, is even more frustrating.

I do hope that someone else can correct me; but I think you just have to plan on heating it up to take it apart, sand down the copper and start over. One good thing is that all of the parts are probably already cut to the correct length . . . . so that's a good thing !

Anyway, your work will leave it better than you found it !
 
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Old 02-18-17, 09:51 AM
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So I should be able to desolder it, rather than cutting it out -- is that right? That doesn't sound so bad. It's my first time doing something like this. I've done some practice soldering with spare bits of pipe that I have lying around, but never done a repair like this. Thanks for all the advice.
 
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Old 02-18-17, 10:00 AM
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Originally Posted by discman017
" . . . So I should be able to desolder it, rather than cutting it out . . ."
Yes, a Professional Plumber would choose to cut and replace with new pipe and fittings instead of charging you for labor cleaning up old copper; but you're your own Customer . . . . and re-cycling is the cool thing to do. You'll find that cleaning old solder off the insides of copper pipes and fittings is the harder aspect; but plenty of heat will get the job done.

I personally take some pride in un-veiling new gleaming copper hiding beneath a nasty patina of greenish mineral deposits.

Good Luck ! (and use a heat shield when working inside that ceiling).
 
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Old 02-18-17, 11:38 AM
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It's still February out there in Colorado; you don't have to deal with this slow leak at this time of year. Draining the baseboard in order to deal with piping whose interior is dry is a chore in itself.

I mention this because you'll soon forget that it was a voluntary decision on your part . . . . once you're deeply involved. There's still time to defer it until a warmer part of the year. But it may add to the excitement !
 
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Old 02-18-17, 01:59 PM
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D,
Just my opinion but since you are going to do this yourself I would try to resolder it first. You have nothing to lose. Sometimes it does not take but the worst thing that can happen is you will have to put in a new tee.

To resolder you must first clean that pipe and get every bit of that deposit off there and make that pipe shine like a new penny. The pipe must be completely empty of water. Any water whatsoever will prevent the solder from melting. Also if you overheat that fitting too much there will be a point where the solder will not take.

Hope this helps a little.
 
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