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[EnergyPlus_Support] Re: question about air-air heat recovery with economizer


You are correct.  Selecting ECONOMIZER or BYPASS should have worked.

I ran your input data file.  You see only 1 error message, at the very
beginning of the simulation (Jan 1 at 00:10).

It turns out that there is a faulty initialization being performed in
the air-to-air heat exchanger model during the "warm up" calculations
at the beginning of the simulation.

Disregard the error message; this initialization issue should have
virtually no impact on your results.   We'll fix it for the next


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Chaoqin Zhai
<chaoqinz@a...> wrote:
> As I read from the IO reference, both ECONOMIZER and BYPASS could
> specified together with the air-air total heat recovery. The
difference is 
> that by specifying BYPASS the outside air flow rate remain the
> value whether it passes the HX or not.
> -Chaoqin
> --On Thursday, November 04, 2004 3:41 PM -0500 Richard Raustad 
> <RRaustad@F...> wrote:
> > Economizer choice for Controller:Outside Air should be set to
> > when heat recovery is used.  See Heat Exchanger:Air To
Air:Generic in
> > the IO Reference Manual for further details.
> >
> > Chaoqin Zhai wrote:
> >
> >> Hi,
> >>
> >> I have an air-air total heat recovery in the system. In
addition, I
> >> set the
> >> system could go into economizer mode when the outdoor condition
> >> within a
> >> certain limit. When I ran the simulation using EnergyPlus, an
> >> message
> >> is generated, which said: HEAT EXCHANGER:AIR TO AIR:GENERIC "ERV"
> >> air volume flow rate is <50% or >130% of the nominal HX supply
air volume
> >> flow rate.
> >>
> >> To my understanding it is because the outside air flow rate is
> >> higher than the minimum outside air flow rate, which is the same
> >> nominal
> >> air flow rate of the ERV, when the system is in economizer mode.
Am I
> >> right? Will this warning affect the calculation accuracy of the
> >> simulation?
> >>
> >> Thanks a lot!

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