Ask Rick: VAV Diffusers | R-Ring – Pressure Independence Option

Q.  Is it required to add an R-Ring for every Acutherm Therma-Fuser installed?  Will the R-Ring replace the return air diffuser (typically installed with regular supply air diffuser)?  In what application do you need an R-Ring?  Why is it an option?

Acutherm SystemIs it required to add an R-Ring for every Acutherm Therma-Fuser installed?    No – only when using specifically for pressure relief on ceiling plenum return applications.

Will the R-Ring replace the return air diffuser (typically installed with regular supply airdiffuser)?   No – Return air diffusers will still need to be designed into the system.

In what application do you need an R-Ring? Why is it an option?  The R-Ring is used as an inexpensive means of pressure relief for the Therma-Fuser. The Therma-Fuser is a low pressure device; requiring from 0.05 to 0.25 in. SP at the inlet. If there is excess pressure then it will need to be reduced by one, or a combination, of three choices; 1. VFD on system 2. Pressure relief damper (Acutherm PIM) for 3. R-Ring. In ceiling plenum return applications we can use the R (Relief) Ring to bypass additional pressure to the plenum return. We only use these on applications with ceiling plenum return.

R-Ring

Bear in mind that the use of the R-Ring is the least energy efficient option. We onlytypically use it in applications where there are a couple of Therma-Fusers that needto be installed in a system. Otherwise we would prefer to use a “PressureIndependence Module”(PIM).

PIM

Related Downloads:  
Options of Static Pressure Control
Pressure Independence Module (PIM)
Bypass R-Rings

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