Thermostat Relay makes a loud buzzing noise when Nest thermostat opens up connection

I have a question about why my 24v Thermostat Relay keeps on BUZZING like crazy when Nest thermostat TURNS the system on (Relay Closed), the older thermostat sometimes causes a milder buzzing, but NOT at all to this extent!

This is the relay: http://www.carlogavazzisales.com/pdfs/switchingprod/cs30.pdf and basically thermostat either turns on 24V A/C unit, OR turns on high voltage baseboard heaters! hence this relay.

Regardless of Heat OR Cold (low or high voltage), the relay starts buzzing like crazy when it's on... in rare occasion buzzing goes away but it buzzes 80% of the time... with older thermostat, it buzzed maybe 20% of the time.

Here's a video of the buzzing: http://www.dropbox.com/s/fytcwnsh15qcj11/IMG_6267.MOV?dl=0

Any help is appreciated. Is it the relay (10yrs old), or Nest thermostat is NOT providing enough current or voltage to the unit? I used a multi-meter and measured voltage provided and it was between 24-26V, so not sure if it's voltage but maybe not enough current?

If it's Nest, what kind of Relay should I replace this with so it works better without buzzing?

Thanks!

Are you sure that relay has an AC rated coil?
What is the relay part number?

crutschow said:

Are you sure that relay has an AC rated coil?
What is the relay part number?

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I linked to the PDF for the relay... isn't that enough info for you?

http://www.carlogavazzisales.com/pdfs/switchingprod/cs30.pdf

That data sheet covers a range of relays. crutschow needs to know which of the relays on the data sheet you are using.

Les.

AlexBC said:

I linked to the PDF for the relay... isn't that enough info for you?

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Nope.
I wouldn't have asked for more info if it was.

Sorry. Here's the part number details.

CF 30 A 002 024 24VAC
NO 30A 277VAC
1HP 120VAC
2.5HP 240VAC

245W

Here's a photo of it.

Obvious questions for AlexBC : do you own a multimeter? Do you know how to use it?

AlexBC said:

Sorry. Here's the part number details.

CF 30 A 002 024 24VAC
NO 30A 277VAC
1HP 120VAC
2.5HP 240VAC

245W

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Okay, the relay's coil is rated for 24Vac, so it's not clear why it's buzzing unless it's faulty.
Can you measure the AC voltage across the coil when its activated?

Otherwise, you might have to try a different relay with the same ratings.

crutschow said:

Okay, the relay's coil is rated for 24Vac, so it's not clear why it's buzzing unless it's faulty.
Can you measure the AC voltage across the coil when its activated?

Otherwise, you might have to try a different relay with the same ratings.

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The voltage is around 25 between bottom leads (red one in pic to black on other side). Also, specs say pickup voltage is 19.2V, so anything above that should be just fine, right? I think it's faulty.

MikeMl said:

Obvious questions for AlexBC : do you own a multimeter? Do you know how to use it?

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LOL... good one! Yes, and "I think so" albeit my meter sucks and can't do proper current measurements on AC.

AlexBC said:

I think it's faulty.

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It would appear to be.