Topics

1

Frequently Asked Questions / Affinity Laws and CSV vs VFD.

« on: April 28, 2015, 09:21:39 PM »

I found this article very helpful in understanding pump curves.

Hope the link and this quote is allowed;

http://www.pump-magazine.com/pump_magazine/pump_articles/article_44/article_44.htm
Observations:

For friction-dominated systems (long pipes, flow transfer cases) VFD saves a very substantial amount of energy, and operates pumps reliably due to close proximity to BEP flow (100% in example shown)

Tried to fix link, added below.  Cary

Tried to fix link, added below.  Cary
For static-dominated systems (injection against constant pressure, lifting against constant head) the energy savings are substantially less, and the pump operates, surprisingly, substantially off-BEP position, not significantly different from a valved flow control case

For cases where both systems are present, an in-between scenario would result

So, in a average residential single household situation. The $2-$4 (I figured pump on a total of 3 hours a day) you would save in electricity per month would never pay the additional cost of the VFD over the VFD's lifespan.

Hope that helps someone else.