This is what I was told for the Alpha2 26-99, might be similar with the Alpha1 26-99: The Grundfos UPMXL 25-124 is currently used in Geo-flo...
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...
FYI, the pressure in a pressurized loop is to ensure no negative pressure occurs when pumping. A vacuum can cause pump failure due to cavitation...
If you have shut-offs on both sides of the pump, they are for pump change outs. Draining the tank isn't necessary, since you already did it...
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