Are you considering the use of Face Velocity Set Back strategies to reduce energy consumption?
How does the installation of ASPS compare with the installation of Usage Based Presence Sensing to reduce face velocity when the user leaves the hood face?
First, if you are considering UBC on your vertical rising sash hoods, you are a prime candidate for the ASPS. That is to say, you have a Lab VAV system and sufficient fume hood density to save energy with these strategies. Now, which system to select.
| Consider: |
ASPS
|
Usage Based Controls
|
| Safety |
The ASPS closes the sash, which maximizes safety. A hood is always safest when the sash is closed. |
The Usage Based Controls do not close the sash, and therefore are not as safe as the ASPS. (NFPA45 can be paraphrased "Hoods should be closed if you are not in front of them." |
| Energy Use |
An Eight Foot Hood with the ASPS installed and therefore closed, exhausts about 367 CFM. |
At 60 LFM, an Eight Foot Hood with the Sash Open 18" exhausts about 660 CFM. |
Score on Safety: ASPS 1 , Usage Based Controls 0.
Score on Energy Use: ASPS 1, Usage Based Controls 0.
Total Score: ASPS 2, Usage Based Controls 0.
If you trust your Lab VAV Controls supplier, ask them which approach is best. Many of our clients have been candidly told that the ASPS is superior to usage based controls.
If they tell you that sash closers would be superior if they really worked, they are unfamiliar with this product.
We suggest our 6 Months Limited Trial Offer so that you can become familiar with the function of this system.
