Air in boiler closed system

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  #1  
Old 02-16-20, 09:10 PM
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Air in boiler closed system

I hear air in the system only when the boiler is fired and running. When boiler is at temp and water is recirculating cannot hear air sound.

Have a new amtrol auto air purge installed. Bled lines well this fall after doing some work to system. Just started hearing these noises the last couple weeks.

thank you
 
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Old 02-17-20, 10:54 AM
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Welcome to the forums.

When your thermostat calls for heat...... the water is supposed to start circulating at that time. Depending on the boiler temperature..... it may not fire at that time but will as the water temperature goes down.

It sounds like you've got air in the system that didn't get bled out.
 
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Old 02-19-20, 05:25 PM
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Agreed, but if there's air in the system wouldn't I hear it when it is recirculating with the boiler fired and when the boiler is not fired?
 
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Old 03-30-20, 02:10 PM
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Looks like you got lost in the shuffle! I have the same thing! When the water is heated and circulating, it's quiet, but when the boiler fires up I hear what sounds like air in the heating loop (?) and it actually sounds like it's turning to steam as it gets hotter!
 
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Old 03-30-20, 05:53 PM
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It sounds to me what you are describing is called kettling. The term comes from the sound a kettle makes when water is being heated. Does the sound seem to be from the boiler itself?
 
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Old 03-31-20, 07:53 AM
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This is another DIY thread where issue or not of air/venting is easily addressed with $8.99 Watts-Automatic-Vent-Valve installed at hight point of system.

Boiler level air scoops, vents and Amtrol auto air purges do not eliminate air at system high points.

Installing a Watts auto vent is preventive maintenance and may make issue moot. For $8.99 why not try it?

https://www.supplyhouse.com/Watts-05...Vent-3679000-p

https://www.doityourself.com/forum/b...ic-system.html
 

Last edited by doughess; 03-31-20 at 08:31 AM.
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Old 03-31-20, 09:10 AM
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Sounds like the sound is in the whole system! Hard to tell! There's no rattling or popping sounds! just sounds like a build up to a steady pressure, then it dissipates when the boiler shuts off! I put a boiler cleaner in but it doesn't seem like it did anything!
 
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Old 03-31-20, 03:12 PM
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Ok, I got a good take on the problem! It does appear to be the boiler kettling! Now what? As I mentioned, I did pit in a bottle of boiler cleaner, but that didn't seem to do anything!
 
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Old 03-31-20, 06:13 PM
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Most boiler cleaners are added based on water volume. Some require several treatments. Kettling is usually caused by deposits in the boiler. The deposits can be from "hard" water or rust from cast iron radiators, steel piping, etc. Let me see if I can get in touch with a couple of guys who used to post here a lot. Hopefully we can come up with a solution for you. BTW; is the boiler gas or oil fired? A make & model might help.
All the air vents in captivity won't help.
 

Last edited by Grady; 03-31-20 at 06:13 PM. Reason: Additional information
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Old 04-01-20, 08:36 AM
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Thanks, Grady!
The boiler is a WM WTGO 5, Series 3 oil fired. I know the boiler is oversized as my house is only 1400 sq. feet! The "monster" is 10 yrs. old! We have hard water, and I have to flush the hot water coil every 3 or 4 mos.
This thing burns 1.50 per and I'd like to downsize to maybe 1.25 but I don't know if the fire box would be too big! The refractory box!
 
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Old 04-01-20, 02:09 PM
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Wow, 1.50 gph for 1400 sq.ft. You could almost heat a screen house in Alaska.Not really but I think you understand my point.
From what I found in the Beckett OEM spec. guide, your boiler came with an F6 burner head. The 4 section which fires at 1.25gph, uses an F-4 head. Without combustion test equipment, I wouldn't chance it. Not saying you would, but could, end up with high CO levels.
I haven't heard back yet from the messages I sent out regarding the kettling.
 
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Old 04-01-20, 03:38 PM
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Wasn't my idea! I questioned the size of boiler before it was installed! And they said "nope this is what it calls for"! I shouldn't have allowed it! 4 guys were afraid to take it down the basement stairs! 😐Had a 4 in there before, and that was plenty big! They had to put in an 8" flue, well, you know!!!
Thanx!
 
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Old 04-01-20, 05:04 PM
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Yep, I know the story. It's unfortunate but there are contractors in every trade who either don't know or "bigger is better".
I did talk with a friend & former co-worker. He asked if you could drain 1/2 to 1 gallon of water off the bottom of the boiler into a bucket & let us know what it looks like. Is there a lot of granular material, what color, etc.
Is your circulator on the supply or return? Location & type of expansion tank? Type of radiation (fin-tube basebaord, cast iron, in/under floor radiant, etc.)? Sorry for all the questions but since I can't see the system....;
 
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Old 04-02-20, 09:37 AM
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I have cast iron baseboard radiators with copper plumbing. Circulator is on feed right above boiler. Took a little more than a liter of water out when I added cleaner earlier and the water was clean, but I'll drain more and check again! Expansion tank is the regular Amtrol 30 4.4 gal.
 
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Old 04-02-20, 11:40 AM
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MP,
From your pic and current info I would like to mention a couple of things I observed.

First, your extrol is too small for your system. Any system that has cast iron radiation must be at least a #60 extrol.

Next is your air scoop. In order for them to work properly they should be 18" from the elbow in order for the air to bleed. If too close to the 90 the water goes by so fast the air doesn't have time to vent. These instructions or recommendations I believe come with the scoop, add to that you have the pump on the supply side to add more force makes that scoop useless with the system running. Now I know in most cases these rules are not followed due to space restrictions and in most cases it goes unnoticed but it is what they want for their product to work as designed.

Since that is new what would have been a better option is a SPIROTHERM air eliminator, It can be installed without the space requirements of the scoop and does not require a hy-vent. It is all one piece and is servicable if something happens. Below is a sight where you can get some info. They are well worth the money.

One last observation. Even though your pump is on the supply you are not getting any benefit from having it at that location due to it being installed before the extrol which is the only point of no pressure change in the system. The idea of the pump on the supply side, pumping away will add higher pressure which will aid in air removal and other benefits ONLY if it is installed AFTER the EXTROL TANK.

https://www.supplyhouse.com/Air-Eliminators-310000, If you go to air scoops and click on Submittal Sheet you will see the install they recommend.

https://www.supplyhouse.com/Spirotherm-Air-Eliminators-311000

Just my thoughts, hope this helps a little.
 

Last edited by spott; 04-02-20 at 12:05 PM.
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Old 04-02-20, 01:20 PM
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The water you drained was from the bottom of the boiler? If so, and it was clean, there's no need to repeat. Often the kettling is due to deposits in the boiler but if the water is clean, generally that would discount deposits. Kettling in a wet base boiler such as yours is quite rare. Honestly, I can't ever remember encountering it.
 
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Old 04-02-20, 04:21 PM
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Looks like I got a good deal (screwing) all around when I picked that company!
Thanks guys, but I still have to figure something out! Probably hard water deposits that I gotta get out of there somehow! Never had so many problems with my old different brand units! 😕
 
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Old 04-02-20, 05:36 PM
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MP,
This is just my opinion but hard water in a domestic system like your tankless is problematic because fresh water is always being introduced leaving mineral deposits behind whereas in a boiler once fresh water is fed and properly bled removing the air the water becomes what they call dead and stays that way unless the system is opened up again or a leak developes so as Grady mentioned if your water came out clean I doubt that is your problem.

If you at least install the hy-vent on the capped nipple, maybe air trapped in the boiler. Do you get a wide pressure difference between cold and hot temps because of an undersized extrol causing excessively high pressures. just a thought.
 
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Old 04-02-20, 05:52 PM
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One question that I don't think we've asked is: When did the noise start?
 
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Old 04-03-20, 06:18 AM
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Grady; I guess I just noticed the noise at the beginning of the heating system!
Spott; I don't have any pressure problem! I keep an eye on it! It runs between 16 - 18 psi usually! Other than the constant change of water through the domestic hot water coil, the boiler has never been flushed or had a change of water since being installed 10 yrs. ago! I thought there might be a problem with the vent because I use to hear the thing working and haven't heard anything out of it for a while! I haven't been able to bleed the radiators because I just had a back operation! Anyhoo, I will change the "hy- vent" and maybe throw some more cleaner in the system and then ------?
I sure took over this tread, didn't I? 😐
 
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Old 04-03-20, 06:12 PM
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MrPop: Don't know what happened to the OP but hopefully he's been following & found something that helps. As much as we tryi to avoid it, sometimes a post will just fall thru the cracks.
Frankly, I'm at a loss but haven't given up. Still researching & asking others in the trade.
 
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Old 04-04-20, 10:05 AM
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Thanks, Grady! Appreciate it! 🚰
 
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Old 04-06-20, 01:39 PM
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Messed with the system today (& messed up!)! Shut the boiler down, isolated the air scoop by the ball valves, checked the air pressure in the expansion tank and then bled the air from the tank! I removed the air vent (no water loss) and took it apart & checked it! It was quite clean & everything moved freely Reinstalled the vent & pressurized the tank! All well & good so far! While the boiler was shut down, I drained about a 1/2 gal. of water out of the bottom and added another liter of boiler cleaner! By the way, the water was very clean! Here's where I messed up! After I put the cleaner in through the 1/2 nipple by the out feed line, I didn't think to fill the boiler all the way with water before I capped the nipple and put everything back on, so I actually added air to the system! DUH!!!
 
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Old 04-06-20, 03:45 PM
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Don't beat yourself up. I don't know anyone who hasn't goofed a few times. Let's hope the air works itself out. I've talked to several guys about your noise & to the man they all said (more or less) "that's a tough one, I'd have to hear it myself."
 
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Old 04-06-20, 07:34 PM
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In regards to the original post - I decided to have a reputable HVAC company look at the boiler. The diagnostics were all great but the only explanation they had for the sound was KETTLING. The Dunkirk gas fired boiler is 20 years old and they said that the mineral deposits inside the heat exchanger are causing the popping noises. You can actually feel a vibration on the piping every time it pops and so I asked if this will become problematic (ruin the boiler or cause damage to the piping because of the popping vibrations). They said that it COULD cause damage but is UNLIKELY it would be catastrophic (i.e. cause a pipe to burst and spew hot water everywhere). They said they could flush the heat exchanger with special chemicals that MIGHT help dissolve the mineral deposits but there's no guarantee and they said it will cost upwards of $1,000 since they will have to cut the copper piping in order to properly flush the system and it will take a while to do all of that. So for now they said if the noise doesn't bother me to just run the system as normal and start thinking about replacing it vs trying to repair/replace a 20 year old heat exchanger.
 
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Old 04-07-20, 08:01 AM
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Watabowtbob: Thank you for the follow up. Their comments were exactly as mine would have been.
Kettling is far more common in dry base boilers, where there is no water below the fire, than wet base boilers. Most gas fired boilers are of the dry base design. Oil fired can be either dry or wet base with wet base being more common. The fact MrPop's boiler is wet base is what makes his so baffling. Again, thanks for the follow up.
 
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Old 04-07-20, 09:16 AM
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Hey, Grady!
I'm gonna take a break for now! I'll let the cleaner work for a while and see what happens! I think it's mineral deposits or some trapped air that maybe is turning to steam(?)! The noise gets louder more toward the end of the burn cycle when it's getting at the highest temp! When I recuperate from my surgery, I'm going to install an air vent in a line off the main loop going to the first radiator. It's the highest and the only place I can get to because the basement ceiling is all sheetrock! And I don't want to mess with the main loop!
 
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Old 04-07-20, 03:02 PM
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Keep me posted. Good luck with your recovery.
 
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