User Expression for DHW heater type

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I am trying to set up a user expression for the type of DHW heater in a
project. When I use the symbolic index control shown below and add it
directly into the equest interface, the model runs fine and the graphical
interface shows the correct heater type.

However, when I save the model, the INP file does not get written with the
#SI notation and when I reload the model, it crashes while loading the BDL
right when it gets to the DW-heater. Does anyone know how to get around

{IF(#PA("DHW_Type")==1) THEN
ELSE IF (#PA("DHW_Type")==2) THEN
ELSE IF(#PA("DHW_Type")==3) THEN

DHW_Type is a global parameter of type numeric.

I also tried putting this code into the default for the DW-heater with a
user expression and this also crashes when trying to load the BDL.

Thank you in advance.


*Sam Mason* P.E., LEED AP BD+C, BEMP
*Encompass Energy, LLC*
P: 443-410-1534
E: sam.mason at

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samuel mason2's picture
Joined: 2015-07-24
Reputation: 0

Hi Sam,
I?m not sure but I don?t think you can apply a default expression to any TYPE keyword ? whether it?s for a DW-heater, a SYSTEM, a SCHEDULE etc.
One alternative is to create multiple DHW heaters, and modify the default expression for CAPACITY to vary with the value of #PA(?DHW_Type?), so that the types you don?t want to use have a .001 capacity.

William Bishop, PE, BEMP, BEAP, CEM, LEED AP
Senior Energy Engineer
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Bill Bishop's picture
Joined: 2012-02-25
Reputation: 7