Attempting to fill holding and pressure tanks with single pump. Fill pressure tank and excess water into holding tank. Possible?
Seems doable to me, but I am not familiar with the available hardware.
There may be a standard way. Here are some concept ideas that may be flawed.
Idea 1: Suppose you had a regular setup pumping 40/60 PSI to your pressure tank and house. Then from that line you would have a 2-port (in and out) relief valve that would open at 50 PSI or above. That gets piped to a float valve that blocks the pipe when the holding tank is full. When that happens, the pressure rises to 60 PSI, and the pump shuts down. Downside would be that the holding tank would not get more water until the pump cuts on again.
Idea #2. Forget the relief valve, but throttle the flow (adjustable valve I am picturing) to the pressure tank so there is enough water to add water to the holding tank while also supplying the house.