A O Smith LTE 250 series - loud, high pitched noise when heating

[lhgrappler]

Hi, I have an 80 gallon A O Smith 250 series light commercial water heater.

It is 277/240 volt. I have the red heater wire on the J terminal, so that it *should* be NON-simultaneous. From the disconnect, I have black to L1, red to L2, nothing to L3, and white unused (capped). (Its 8/3 wire on 35 amp breaker). We also have a cash acme water heater booster. We are on well water, but have filters before the water heater.

We powered it up just a couple days ago, it was full of water before powering up. I noticed a slight humming from both elements, which I thought was odd given that its supposed to be non-simultaneous. Then today when it started heating the water it got much louder and higher pitched - sound coming from both elements (or at least the upper and lower panels).

I went ahead and turned off the breaker.
Any ideas? It was purchased over a year a go and sat in our shop (unconditioned) while we slowly renovated our home.

 

[Fitter30]

Don't see a J terminal but the diagram in manual red and black to to upper limit 1& 3 for non simultaneous. Should also have a mechanical ground lug. Normally green but might not be. Kept a new heaterin a garage for 5 years they shipped them dry.
Page12 T6 diagram. Way most heaters are wired top element call for heat when satisfied turns off sends power to lower element when satisfied turns off sends power back to the top.

https://hdsupplysolutions.com/wcsstore/ExtendedSitesCatalogAssetStore/product/fm/additional/20/208457_InstallationGuide-PDF.pdf

 

[Sponsor]

 

[lhgrappler]

** IT does say not to use 6100kw non-simultaneous on 240 V - BUT I have 8 awg, and 35 amp, so that shouldn't be an issue.

 

[lhgrappler]

Don't see a J terminal but the diagram in manual red and black to to upper limit 1& 3 for non simultaneous. Should also have a mechanical ground lug. Normally green but might not be. Kept a new heaterin a garage for 5 years they shipped them dry.
Page12 T6 diagram. Way most heaters are wired top element call for heat when satisfied turns off sends power to lower element when satisfied turns off sends power back to the top.

https://hdsupplysolutions.com/wcsstore/ExtendedSitesCatalogAssetStore/product/fm/additional/20/208457_InstallationGuide-PDF.pdf

That looks like its for the 200 series, but thanks. I posted pics from the 250 series pdf

 

[Fitter30]

6100 watts 25.4 amps on 240vac
Don't see a 200 series doesn't matter there all wired the same single phase.