Constant vs. Variable Differential ∆P pumping

Constantin

Perhaps not surprisingly, I am a bit out of my element when it comes to understanding the capabilities of Wilos Stratos series of pumps. There are a number of things that separate the ECO from the regular stratos, one being constant vs. variable differential ∆P pumping.

I'd like to better understand the benefits and drawbacks of variable vs. constant differential ∆P pumping... presumably constant differential ∆P was omitted from the ECO series as a means of differentiating the two series from another (besides all the other features, such as voltage, etc.) I'd think that the constant ∆P feature would be more desirable for some systems, but I'd like to know more.

Based on HDS, it would appear that one Stratos 1.25x3-20 or two ECOs would be able to supply the whole house. Because of some permanently-open zones (riding the reset curve) either configuration would always allow the pumps to be running (i.e. no deadheading) until WWSD kills them for the summer.

With the ECOs, I'd be closer to the pump curve if all zones are calling for heat (~9GPM @ 8') than with the Stratos -20. Plus, I wouldn't have to run a new power service to the boiler room to accommodate the Stratos -20. On the other hand, having a single pump handle everything is pretty appealing also. What are the pro's and cons?

MechTech_2

Variable

We have only used the Delta P Variable mode on our multiple zone system. However, we are contemplating the idea of using it on a ground source system, and our borehole conductivity testing equipment, where dialing in the exact gpm would be advantageous.

Mark Hunt_6

Check your e-mail


The Delta Pressure constant (DPc) mode would be used in situations when the head requirement remains constant but flow requirements change.

Delta Pressure variant (DPv) will be the control mode used for 99.9% of residential applications and this is why the ECO does not have the DPc option.

Head over to the new Wilo site and download the "Wilo Select" software. It's got some pretty cool stuff on it. Just be sure to "save" the file to your computer.

Mark H

Constantin

Thanks for the e-mail, Mark

I think I'll stick to two ECOs for the sake of not having to run a new power supply to the boiler room... plus, some redundancy. The variable differential mode will likely suffice. Thanks again. C.