[Equest-users] Cooling tower - Two-speed vs VFD fan, bug?

R B slv3sat at gmail.com
Tue Jun 4 09:57:08 PDT 2013


The default on vfd is 40%. I see savings compared to every other option -
one-speed, discharge damper etc. None of them use the fan-speed vs power
fan curve except two-speed and vfd options. So, basically both are working
in the same way with a penalty of vfd losses in the vfd case? I would think
that the two-speed option will not need a curve.
Thanks,
-Rohini


On Tue, Jun 4, 2013 at 8:37 AM, RobertWichert <robert at wichert.org> wrote:

>  I recall having to pick the "minimum speed ratio" box or something like
> that before the VFD would show savings.
>
> Have you set that?
>
>
> Robert Wichert P.Eng. LEED AP BD&C+1 916 966 9060
> FAX +1 916 966 9068
>
>
>
>
>
>
>
> ===============================================
>
> On 6/3/2013 7:22 PM, R B wrote:
>
>  Hi all,
> Has anyone tried to see the savings associated with upgrading two-speed
> fan to VFD in a cooling tower? I see increased energy use due to the vfd.
> on further digging, it looks to me that both two-speed and vfd fans use
> the same fan performance curve. Is this the case or am I missing something?
> Thanks in advance,
> -Rohini
>
>
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