BTU Calculations

[kyle.r.markham]

We are trying to determine the total BTUs/hr for our Cisco equipment and want to make sure we are calculating this correctly.

For example, we have 6 Cisco Catalyst 3750X-48T-S each with two C3KX-PWR-350WAC power supplies.  According to the information found on http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-3750-x-series-switches/data_sheet_c78-584733.html?mdfid=282979364 the total Output BTU is 1207 BTU/hr.  Since this number is listed specifically for this power supply and we have two power supplies in this switch, would we then say that each switch produces 2414 BTU/hr (1207x2) or is that not necessarily the case?

[Joseph W. Doherty]

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Posting

I don't believe that's the case.  I would expect a slight BTU increase for two power supplies pulling the same power as a single power supply, but not twice the BTU.

[kyle.r.markham]

That is what we would expect as well, but would like to know how to accurately calculate what the actual number should be.

[Zach S]

Kyle,

As Joseph said above it wouldn't exactly be double the BTU's for twice the power supplies. There is a lot that would go into figuring out exactly how much heat the setup is actually dumping out. If you have a controlled area that has a constant (or close to temperature) and you leave the switch(es) in it for a period of time, then see the change in temperature, then you can see how much heat the units are actually giving off. This however a physics problem, that would be a little ridiculous and time consuming for most people to deal with.

If you go by the datasheet specifications 1207 BTU/h per PSU, then you can safely figure that is the maximum output, or worst case scenario.

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Try contacting Cisco sales for a more exact answer with two power supplies, although as Kyle the BTU rating should be about worst case (i.e. with unit full with full traffic on all ports) so I doubt adding the second power supply would add much.

(If you do get an exact number for the addition of a 2nd power supply, from Cisco, if you can, post that information on this thread.)