Bad circulator? System 2K boiler

KyleO

I can't post a video of the sound. Any ideas how to stream the sound? 
I have a fairly new (5 years) System 2K oil boiler. After it heats up and the thermostat stops calling, the circulator continues to do it's thing as expected. 
But it makes a rattling noise that's audible from across the basement with the door closed. Is this a sign of a bad check valve vibrating in the circulator pump? Anything I can do to fix this?
Thanks all

KyleO

Forgot to mention, I already tried bleeding it thinking there was air in it. I did get some air, but not a lot. It did get a little quieter but an hour later it was back to the same volume. 
When the heat is on, it isn't audible as much. 

Steamhead

@Roger ?

hilltown

Don’t believe there is a internal check valve in theses circs..

HVACNUT

So the noise occurs after the heat call ends and the zone valve closes?
Does it purge to the water heater after a heat demand?
Does it make the noise on the DHW call?
If so, could be a restriction in the plate HX.

KyleO

HVACNUT said:

So the noise occurs after the heat call ends and the zone valve closes?
Does it purge to the water heater after a heat demand?
Does it make the noise on the DHW call?
If so, could be a restriction in the plate HX.

Hi again @HVACNUT thanks for the help as always.
The noise occurs after the boiler stops heating, but while the zone valve is still open (meaning the hot water is still circulating using the remnant heat). Then the zone valve closes and circulator shuts off and noise stops. 
But yes, the rattle noise isn't happening when it's heating or circulating and heating. 
And no, the DHW call doesn't trigger the circulator so no noise then. It's only when a zone calls for heat, and it's still circulating after the boiler stops heating up.
How would I rule out the heat exchange plate? 

Roger

@KyleO , it sounds like there may be a mechanical problem with the circulator.  Sometimes there is a critical frequency where noises can occur, and it may be related to a very specific flow rate. Changing the cartridge in the circular would likely make the noise go away; there is no check valve in that circulator.  It does seem odd that it does not make the noise when the burner is running, but does make the noise in the thermal purge mode (the flow rate should not have changed through that transition).

Best,

Roger

KyleO

Update: Replaced the circulator and it solved the issue...got a different looking pump from TACO, seems fine
(and Roger, it was making the noise while the burner is running, just harder to hear because the burner is louder)

Roger

Nice work, @KyleO - I’m glad you have it resolved and thank you for updating us all with the additional information and solution!

HVACNUT

Sorry @KyleO, been busy, but thought of you yesterday while replacing a brand new 0014 that was making a racket while commissioning a new boiler done by the installation crew.
I left the volute and just replaced the motor/cartridge assembly because space was tight and no room to spread apart the LLH.
Glad you got it.