Boiler's groaning and so am I

Duncan_18

Yeah, that was one of the first things I tried... Ended up I lowered the pressure at the combination gas valve regulator so much it started a slow pulsing. You're right, it works sometimes, Ive come across that myself. But it's not working this time. I'm assuming it's burner related because it sounds like the noise is coming from there.

I'm looking for any and all ideas. There are two Y strainers on the system (that's another story). I'm starting to wonder if the problem's possibly on the water side.

Fishin' for ideas...

Duncan_19

Boiler's groaning and so am I

Like the Maytag man, we install boilers and don't hear from our customers for ten years or so, when something wears out. At least we hope our systems run that dependably. God help 'em if they treat their cars like that!

Anyway, I've got a ten year old install (induced draft, propane Slant/Fin Victory, 90k input) that has started to make a humming or groaning sound on start up of each cycle. It's still in the 40°s at night here in the hills.

I hear it as the burners ignite and it dies down after a minute or so.

Sounded like it was coming from the burner area, and I've dealt with this before by looking at the combustion side of things.

Thinking I had it figured out, I replaced the ribbon burners. No luck.

Noticing the sound changed as I adjusted gas valve manifold pressure, I thought the combination propane gas valve (Honeywell) may be having trouble regulating and replaced it. No luck.

Any ideas? The client doesn't remember hearing the noise until after an on-demand water heater was installed. I'm tempted to install a new second stage regulator at the house to see if this fixes it. Probably not a question of regulator capacity to handle the appliances, but I suppose it's a possibility. I bumped the house pressure up to nearly 14"w.c. and all pressures look good with boiler operating or not.

You know, it's too damn humbling to troubleshoot by shotgunning every part in the sytem, and I suspect the water heater cause/effect is a red herring, and I'm running out of ideas. That's only after three ideas, too. *groan*

My questions:

What are other possible causes of humming on boiler ignition?

Has anyone ever heard noises like this caused by the water side of the system?

Any ideas?


Thanks in advance to the hundreds of years of accumulated experience here. Good to see this place still rollin' along!

Duncan

Uni R_2

Insufficient Airflow

Is the induced draft flowing the required amount?

Duncan_20

airflow

Didn't measure vent pressure or flow, but it's enough to prove the vent safey switch and allow the burners to kick on.

Didn't climb on the roof and do an absolutely POSITIVE check on the entire vent for possible obstructions.

Have you seen vent problems cause noises like this? I'll put that on my list of things to check out on my next visit.

Unknown

I had a similar

prob like that but on NG,,,S/F too, 3 Caravan atmospheric steam units,,I reduced the gas pressure at each main valve slightly and it went away, still scratching my head why!

Dave

[Deleted User]

Duncmeister!!

One word...

Chelates.

Call Dennis Bellanti (303-320-4833)and get yourself a gallon of his specially formulated (CST-50) hydronic cleaning agent, pump it in and go back to fixing mail machines, or fishing, or hiking :-)

You coming to Tommies 50th?

Also going to try and put something together up at the ranch in Heeney later this summer.

Good to see you my friend.

ME

Boilerpro_5

Burner fluting...

I've come across this several times. Every Burnham 2 series in the Power vent and chimney vent models in the 4 and 8 sizes I have worked on have this problem at low operating temps (140 to 160 or so). The Galaxy Slant Fin steamers I have installed do this too. What has always worked is throttling the primary air shutters on the burners to change the air velocity. It's how a pipe organ works....vibrating air column. Great for a Pipe Organ, not so good on a boiler.

Boilerpro

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Duncan_18

Thanks, pro...

I should've played with that some more, I guess. I did some adjustments, but I'll have another crack at that end of it.

I WILL let you know if that works on this job.

Duncan_18

Ah so-o-o-o....

Ze specially formulated cleaning agent!

I dunno, Mark... I kind of run with the Car Guys on this one: If the additive doesn't have the word "Miracle" in the name, I don't really trust it. Is there a premium grade "Miracle" CST-50 ? [grin]

Tommies 50th? The bum didn't invite me! Thanks for the heads-up, it gives me time to come up with some comb-over jokes.

I've always wanted to go to the Heeney Tick Festival, but I bet your get together will be way more fun! Count me in! Good to hear from you, buddy!

bob_50

Duncan

What's the gas pressure in the burner manifold? Why are you useing a gas valve with a pressure regulator on LP?

[Deleted User]

Humming Burnham Atmospherics

Dunc and Dave,

As for audible noises in cast iron boilers, the only experience I have had was with some Burnham atmospherics at altitude (11,000' ASL). I could affect the noise by significantly choking gas flow (LP) and oddly enough, I could STOP the humming by pressing down on the flue gas collector. Turns out that the "noise" was a harmonic condition being set up between the atmoshperic burner and the top of the flue gas collector. Changes in the primary air mix made no difference. Burnham paid me to change out the burner to their newer 2" Viessmann looking stainless steel unit. Noise stopped.

But, by far and away, the noisiest boilers have been the CFT boilers with microbubble steam flash occuring at the tube to water interface, and the ONLY way I've been able to eliminate this noise is with the chelates. It does soemthing to the tube to water interface to eliminate microbubble steam flash.

One way to determine if it is MBSF versus burner harmonics is to listen to the humming after you cut the burner off. If the noise stops immediately, its probably harmonics. If the noise tapers off, its MBSF.

One way to cure it for sure and lower your clients fuel bill by 30% (minimum) is top convert them over to a mod con :-) And hey, it qualifies for a Federal Tax rebate (OK, only slightly better than a sharp stick to the eye, but hey, its better than no sharp stick to the eye...:-))

Also, if there are glycnoids in the system fluids, you are almost guaranteed that it is MBSF which gets worse with time.

G'Luck wit yer sitchumication.

ME

Duncan_21

manifold pressure

I set the house pressure at 14"w.c., and the manifold pressure according to boiler nameplate specs, which, if I remember correctly was between 9.5" and 12".

I played with the manifold pressure over the entire range within nameplate specs. Lower pressure seemed to make the noise less in volume, but it was still there on startup at any manifold pressure.

I'm using a gas valve with a pressure regulator on LP because it's there, an OEM part that comes with the boiler. Talking about the pressure regulator built into the VR8024A 2258 combination gas valve. On the Honeywell valves, there's a stronger regulator spring for LP than for Natural Gas, a black regulator adjustment cover cap and a warning label if it's a conversion.

Duncan_22

Manifold Pressure

I set the house pressure at 14"w.c., and the manifold pressure according to boiler nameplate specs, which, if I remember correctly was between 9.5" and 12".

I played with the manifold pressure over the entire range within nameplate specs. Lower pressure seemed to make the noise less in volume, but it was still there on startup at any manifold pressure.

I'm using a gas valve with a pressure regulator on LP because it's there, an OEM part that comes with the boiler. Talking about the pressure regulator built into the VR8024A 2258 combination gas valve. On the Honeywell valves, there's a stronger regulator spring for LP than for Natural Gas, a black regulator adjustment cover cap and a warning label if it's a conversion.

Duncan_22

Sure hope it's not glyconoids

They make me paranoid!

Oh yeah, well aquainted with the CFT microbubble whale songs. This is the pipe organ ghostly harmonica kinda noise.

It's a cast iron boiler. You know the Slant/Fin with lotsa heat-absorbing pins on the fire side.