Hot water boiler banging ...

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Old 01-11-09, 07:32 AM
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Temporarily removed radiator and capped line - Would this cause banging?

Hello all!

I have a banging noise coming from my boiler when the burner reaches a certain temperature. I'm almost certain it is air in the system and have a few questions concerning what should be done.

First off let me give a bit of the backstory. I tore out my bathroom in November of 2008 to do a complete remodel and removed the cast iron baseboard that was there. As of now, a new radiator has not been installed. I did install new lines that are capped.

If air was trapped in that either the supply or return line (I'm sure there is) could that be making it's way back to the boiler?

Each radiator's supply and return go directly to the trunk line in the basement.

If that would effect the air in the whole system, can I get it out temporarily. I've ordered a Runtal radiator but it has yet to arrrive.

It's a Bryant system that is about 10 years old with no zones. I also have the old style expansion tank hanging in-between my floor joists.

Thanks in advace for all the info.

Best Regards.

Jeff
 

Last edited by mmstoned; 01-11-09 at 07:57 AM.
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Old 01-11-09, 08:33 AM
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I suppose anything is possible, but air normally doesn't cause a banging noise. I would suspect sediment in the boiler with maybe low pressure. What pressure is the system running, hot?

Air is best removed by bleeding the radiators.

Another comment. Depending upon how your radiators are piped, just capping the supply and return lines of the missing radiator may cause the heat to be interrupted to other units. Are you having any such problems?
Doug
 
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Old 01-11-09, 08:59 AM
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The heat in the other radiators seems to be uneffected.

The timing of the "banging" or "poppings" seems to conincide with the removal of the old radiator. I just thought that there is air in the supply and return lines of the removed raiator that effecting the system.

The operating pressure when hot is about 17 to 18 psi.

I bleed the other radiators quite often whereas before I didn't need to .
 
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Old 01-11-09, 09:41 AM
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Each radiator's supply and return go directly to the trunk line in the basement.
Both the supply and return come off the same large pipe? Or two separate pipes?

If they come off one pipe, take a close look at the tee fittings used. Do either or both of them have 'arrows' on them? or red rings? or labels that say 'Monoflo' ?

If so, my recommendation would be to remove the caps from the pipes, and connect the two pipes directly together for now... that type of tee fitting would indicate that it's a 'diverter tee' system and by capping those lines you are disrupting the flow to the rest of the system. The air trapped in those risers can be getting back in to the other pipes.

But as Doug says... air usually won't 'bang' ... unless maybe it's hitting a check valve somewhere in the system ...
 
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Old 01-11-09, 09:47 AM
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I think maybe my terminology is messed up. Upon further research I would say it's more of a kettling sound as opposed to a bang.

I should have been more clear in my posts. There is a main supply and return line in the basement. The supply and return line both lead back to their respective main lines in the basement.
 
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Old 01-11-09, 10:21 AM
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If you have separate supply and return mains, then you probably are OK with the capped pipes. You might consider installing bleeders on them to fill the pipes with water...

A 'kettling' sound... trying to hear that in my 'third ear' ... but the Roy Haynes festival on the radio is drowning it out...

Can you 'locate' the source of the sound? Is it coming from the boiler? In the piping? at the circulator?

In any case, it wouldn't hurt to get the air out of those risers...
 
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Old 01-11-09, 10:33 AM
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The sound is coming from the boiler itself. It only happens when the burner is firing and the temperature is about 180 degrees.

If I install bleeders will I be able to get the air out of both the supply and return lines or just the supply?

Hopefully the new rad will be in soon and I can eliminate this from my possible list of solutions.

Is there a good, easy to use descaler that I can use to clean up the interior of the radiator?
 
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Old 01-11-09, 10:44 AM
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Maybe coincidence with the removal of the rad... or, maybe there was some amount of sediment in the old piping that was displaced into the boiler ... because what you are describing sounds like sediment in the boiler.

The pressure in the boiler should push water up both supply and return ... If you install valves on each pipe, opening that valve would do the same thing as bleeding the rads.

I'm wondering though if removing that rad decreased the flow through the boiler... how many other rads are now operating? and are any of them 'choked' down by a partial valve closure at the rad (for balancing, etc)? If the flow through the boiler is insufficient, the heat can't get out fast enough...

I can't really help with flushing, if that's the expected solution.

Is there a BYPASS valve on the piping near the boiler?

Pics might help ... free account / www.photobucket.com / upload there / drop link here for us to view.
 
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Old 01-11-09, 11:18 AM
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Is this one pipe around the basement and each radiator supply and return are connected to the same pipe? If so the removed radiator must have the existing supply and return pipes connected together either above or below the floor.
The kettle sound sounds to me like a mineral build-up in the boiler. It comes from adding too much fresh water to the boiler system. If you turn the boiler off when it is doing it the sound will gradually die off although rather quickly but you can normally hear it tone down. If you have valves on the supply or return close one and let the boiler get hot and start making the sound. Than open the valve. If the noise goes away quickly I will also assume it is a mineral build-up.
Try a de-scaler but when this is started the mineral build-up is already near 1/4" thick and I have not seen or heard of much luck getting rid of it.
If you get it out or replace the boiler find the small system leaks.
 
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