The pump is ard 0.5kW only, if you do not turn on the water, the pump will be in standby mode and would not consume much electricity. Your water heater is 3.6kW while a Grundfos water pump consumes 7 times less electricity compared to your instant heater.

Some houses cant hear anything at all while some will have bombing noise. What i can tell you is Grundfos pumps have low noise operation, whether you can hear it or not is depending on how your plumber install it and the structure of your house.

usually people will just lift the lever up 50% then adjust the preferred temperature, rarely will turn full to hot den lift up the lever. If you are using a storage tank, i guess there is a button to reduce the max temperature.

Grundfos pump is powerful, if you are those who wants to get rain shower and have strong water pressure like hotels then GRUNDFOS is the choice. There are some customers who told me, just shower 5 min only, no need so good one, then get an instant heater with built in pump.

I use Joven, its almost like instant heater, fast heat up. I used to have instant heater, within 3 years need to change 2 times.

707 was the second set i bought, within the 3 mths, the push button came off, although under warranty, but they came and just glued the stick connecting to the button, and it came off within one month. And they said that that is not guaranteed, bad product support.