My Geo supplier quoted me a QT two pump single speed flow center. I see they also offer it in a 3 speed as well. Is there an advantage to one or the other?? The heat pump has a two speed compressor. I would think it would need less flow at half speed. Thanks !!
The three speed has a selector to set the pump speed. The speed isn't controlled from the heat pump. That being said, it is sometimes useful to turn down the pump speed to save pumping energy at the cost of extra compressor energy.
If possible, design the loop so you only need one pump. Make sure you use an efficient pump. Looks like the QT two pump single speed flow center uses two 26-116 pumps. These are energy hogs. Don't use them. You want to use a 26-99 pump, or even a variable speed pump if you want to match flow to compressor speed. Search this site for 26-116 and you will find lots of comments about this issue. 2x 26-116 will use ~760 watts. A single 26-99 on high will use ~230 watts. For example see here: https://www.geoexchange.org/forum/threads/which-flow-center-for-new-system.7821/
