My experience with a TACO variable speed pump that is supposed to vary the pumping speed according to the Delta-T of the water out vs the water returning has been well a huge disappointment.
I put a 'Kill-a-watt' on the pump, and it shows virtually zero electricity savings over a standard TACO 007. I was expecting a notable difference in watts used, but I see nothing..
It's just a noisy, expensive pump.
This pump is on my supply loop from the boiler room/building to the house and two water/water heat exchangers transfering heat into the heat and DHW tank..
What I was led to believe from the description of the Delta-T function and variable speed reaction to the Delta T was that if the house and DHW were not pulling any BTU's from the water loop, then the Delta T would be low or almost nonexistant. The hot water going to the house was the same temperature when it returned to the boiler, the pump description says that the pump will idle down to very low speed under this circumstance.
Then when there is a large Delta-T, the pump is supposed to speed up to pump more water [BTUs] when more are needed in the house.
Well the pump does show some VERY minor differences in power used, but I ran and recorded 'normal pumps' and this computer-controled 'variable speed' pump.. On a minute by minute basis, yes the pump does vary speed and watts used, but over a 24 hour period, there is NO difference in watts used..
The TACO rep I spoke with on the phone said that the pump is not intended to save electricity, but to increase pumping capaciy as needed.. Well, it should then save and reduce watts used, right?? The rep said no, they do slow the pump down and speed it up, but the electricity difference is negligible..
So I asked then what is the reason that the pump was developed and sold, and what is the perceptible 'improvement' a consumer or installer will see? The rep said that the biggest difference would be a reduction in pumping 'noise' from the water flow in the pipes ???? WTF???
Who the hell has a ?$200 problem with rushing water noises in the pipes? Not many when a standard TACO007 costs about $70 !!
Anyway I would HIGHLY recommend a conversation with TACO, Grundfos or other pump makers before spending any money on a pump that claims to be some form of magic.