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Re: [EnergyPlus_Support] Heat recovery warning



Report the supply (primary) and exhaust (secondary) air streams mass 
flow rate using the output variable report below.

Output:Variable,
*,
System Node MassFlowRate,
TimeStep;

Substitute the nodes name for the HX's supply and exhaust air streams 
for the * above.

Then compare the average of these 2 values with the nominal HX supply 
air flow rate specified in the HeatExchanger:AirToAir:SensibleAndLatent 
object (named AHU HEAT RECOVERY).

You should see that the average is out of range. The manufacturers do 
not recommend operating outside the range of <50% or >130%.

You could also change the type of HX, there is a sensible only flat 
plate model that does not have this restriction (if you do not need 
total heat recovery).

johnnyklemke wrote:
>  
>
> Hi all,
>
> I've been running a model with ASHRAE system 8 (VAV with heat 
> recovery) and could not solve a warning with the heat recovery component:
>
> HeatExchanger:AirToAir:SensibleAndLatent "AHU HEAT RECOVERY"
> ** ~~~ ** Average air volume flow rate is <50% or >130% of the nominal 
> HX supply air volume flow rate.
> ** ~~~ ** Air volume flow rate ratio = 7.454E-002. Occurrence 
> info=SAO_PAULO/CONGONHAS - BRA TMY3-837800 WMO#=837800, 01/02 06:00 - 
> 06:10
>
> ===== Recurring Error Summary =====
> ************* The following recurring error messages occurred.
> *************
> ************* ** Warning ** HeatExchanger:AirToAir:SensibleAndLatent 
> "AHU HEAT RECOVERY": Average air volume flow rate is <50% or >130% 
> warning continues. Air flow rate ratio statistics follow.
> ************* ** ~~~ ** This error occurred 999249 times.
> ************* ** ~~~ ** Max=0.499985 Min=7.383128E-002
>
> Can anyone help me on this? How can I solve this issue? I don't know 
> how to measure this 50/130% of average air volume flow rate.
>
> Thanks,
> John
>
> 

-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
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Phone:   (321) 638-1454
Fax:     (321) 638-1439 or 1010
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