Static pressure calculations

[LinearPancakes]

So I've pretty much decided to DIY our MVHR install using a radial system. I'm also having a go at designing it, but am not sure how to calculate the total static pressure of the system, so I can make sure it's not working too hard. The passive huas trust indicates it should be <100 Pa ideally.

 

I get the general idea of pressure drops, and how to work out the pressure drop of an individual run. You sum the pressure drop from each component in the run, bends, ducts, attenuators, at the correct diameters & lengths.

 

And I'm pretty sure you need to add the pressure drops from both sides of the supply/extract. (So outside->mvhr + mvhr->inside + inside->mvhr + mvhr->outside)

 

But what I don't understand is how the pressure drops of the multiple runs from the manifold, each with different lengths and bends, should be combined to a total static pressure for mvhr->inside and for inside->mvhr.

 

Can someone help plug the gap in my understanding?

[JohnMo]

The system pressure are worked out for the extract and supply.  The route for extract with the highest pressure drop determines the extract pressure drop, the same is true for the supply.

 

You need the datasheet for your materials, ducts, manifold, nozzles etc. and your target flow rate.  From this you should get the info you need.  Basically the high the flow rate and the longer the run the higher the pressure drop.

[LinearPancakes]

20 hours ago, JohnMo said:

The route for extract with the highest pressure drop determines the extract pressure drop, the same is true for the supply.

Thanks @JohnMo, that's what I was missing, you use the maximum.

[JohnMo]

Yes