I'm installing a 4 ton GSHP split system and had planned on an open loop. When I replaced my deep well pump the well guy said variable speed pumps are trouble and constant-flow/cycle-stopper valves are energy hogs, just pump and dump. I realize that my well system volumes and pressures aren't efficient for GSHPs and the cycling will shorten pump life. An enormous pressure tank may work to reduce cycling but is cost prohibitive, they all seem to be bladder tanks I've had nothing but trouble with over the years and only hold a fraction of what their size and cost might suggest. I have several large ponds on the property (3-10 acres) but the nearest is 500' horizontally and probably 25 feet vertically from the HP, I'm told pond loops or raw water open loop is out of the question.
What I had in mind was a large buried tank, 3-4k gal. minimum, with a pump providing around 10 gpm at low pressure to the HP. To fill the tank would be a float switch on a timed relay controlling the solenoid valve, the well would then start and run continuously until the tank was almost full. With a little thought it might be arranged that the tank would 'top up' when there is little other water demand. Used large tanks seem to be easy to come by in the area, I've got an excavator for installation and the well is capable of continuous operation. There might even be the possibility of capturing rain water from the gutter system and directing it into this tank though screening and filtration issues may be the downfall of that idea.
Could this be a viable setup or should I just give up and plumb 60psi water to the HP and let the well cycle itself to eventual death?
Thanks for listening to the delusional thoughts of a newbie.