IES-VE User Forum

Hello!

(I hope, that is the right place here)

In my simulation model I use the auxiliary ventilation for fresh air. The temperature of the supply air of the Auxiliary ventilation system I controlled with a temperature profile, wich depends on room air temperature and the outside air temperature.
Thats it:
if((to<=16)&(ta<=20),22,if((to<=16)&(20<ta<=26),20,if((to<=16)&(26<ta),18,if((to>16)&(ta<=20),20,if((16<to<=20)&(20<ta<26),to,if((to>20)&(20<ta<26),20,if((to>20)&(ta>=26),18,18)))))))
Yes, it is a little bit heavy, but in Excel it works.

But the backwards calculation from the auxiliary ventilation gain from vista plot to the supply air temperature it makes no sense. Here my question: It is possible to read out the controlled supply air temperature? I think something is wrong, but i could find it.
Could you help me?

THX.

V 6.4.0.12

ok ok. The formula system need it very very simple and bit by bit.
I try somehing like that:
(to<20)&(20<ta<=26)
But my results dosen't look nonsatisfying. So I try a lot to find the reason. In the end I split the formula to:
(to<20)&(20<ta)&(ta<=26)
and now my results looks like I looking for. Sometimes the life could be so easy.

But one question remain: It is possible to read out the controlled value of a formula? Thats still intereinteresting.

Hi,

we do see some wild and wonderful formulae used in VE. Usually because VE does allow you to be creative to define controls and often rather than providing an interface we give you access to formula variables.

Anyway there is no way to debug formula profiles in the way you have suggested. You can usually output to a table the variables you have used in your profile and then calculate by hand to check how it should operate at each step but I often suggest if you are troubleshooting a formula then apply it to a simple on/off control where you can see the value it takes for example apply it as the variation profile for an internal gain then you can look only at that gain and understand how the formula itself works over the simulation period on a direct Vista output.

Same especially applies for MacroFlo, you can look at the open area of the individual window in Vista and see the performance of it over the simulation period whereas if you look at the MacroFlo gain or airflow it will also depend on other factors and include the leakage so it makes it harder to see only how the formula profile is operating.

Also start simple and build it up if you don't think the overall formula is working properly, this is a methodical way to spot the error in the formula. seems like this worked well for you this time and you have been able to make it work now so well done!

Phil