What Is an Open-Loop System?

An open-loop system draws groundwater from a well, passes it through a heat exchanger, and returns it to a discharge well or approved outlet rather than recirculating it. Because it uses actual groundwater, it depends on adequate well yield and acceptable water chemistry.

Also called: open loop · groundwater heat pump · pump and dump

Why it matters to you

Open loop can perform very well where groundwater is plentiful and clean, but it introduces considerations a closed loop does not: well capacity, water chemistry such as iron and hardness, and the regulatory requirements that attach to withdrawing and discharging groundwater.

What to do about it

Treat water quality testing and the permitting path as part of feasibility, not paperwork to resolve later. Discharge arrangements in particular are governed by state and local rules and are not a design detail to be improvised.