Standing Column Well Calculator

Determine geothermal open-loop circulation GPM, peak bleed water discharge rate, bedrock heat exchange density (W/m), and submersible pump lifting power.

Thermal Load (Tons)

Total Well Depth (Feet)

Static Water Level (ft)

Bleed Control Setting

Design ΔT Across Exchanger

Well Casing Diameter

Total Water Circulation Flow

48.0 GPM

Bleed Discharge: 4.8 GPM during peak load

Bedrock Heat Density

65.6 W/m

68 BTU/hr per linear foot

Pump Lift Power

1.8 HP

1.34 kW continuous draw

Footage per Ton: 60 ft / ton (vs 200 ft closed loop)

Daily Bleed Discharge Volume: 6,912 Gal / day max

Up-Annulus Water Velocity: 0.45 ft/sec (laminar return)

Standing column well provides 3x higher heat transfer rate per foot of bore than closed-loop U-tubes.

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Standing Column Well (SCW) Thermodynamics

A Standing Column Well is a semi-open geothermal borehole drilled deep into competent bedrock (typically 1,000 to 1,500 feet). Groundwater is pumped from the deep bottom of the water column, circulated through the building's heat pump heat exchangers, and returned directly into the top of the same well column, with water in direct thermal contact with bare rock walls.

Bleeding Control Mechanism

Bleed Fraction:
During peak summer cooling or severe winter cold, a fraction (typically 5% to 15%) of the return water is diverted (bled) to stormwater discharge or secondary injection wells instead of being returned to the well.
Induced Groundwater Inflow:
Bleeding forces fresh, ambient-temperature groundwater from the surrounding aquifer into the rock fractures, instantly stabilizing the well column temperature.
Footage Efficiency:
Because groundwater is in direct contact with the rock without the thermal resistance of HDPE pipe walls and grout, SCWs require only 40 to 70 feet of depth per ton compared to 150 to 250 ft/ton for closed-loop boreholes.

Frequently Asked Questions

What is the primary advantage of a standing column well over closed loops?

Direct water-to-rock contact eliminates the thermal resistance of HDPE pipe and grout, allowing a single 1,200-foot well to support 20 to 25 tons (requiring only 50-60 ft of drilling per ton vs 200 ft/ton for closed loops).

What does bleed mean in a standing column well?

Bleeding refers to discharging 5% to 15% of the circulating water to an overflow discharge rather than returning it to the well. This induces cooler, fresh groundwater to flow from the rock formation into the column.

What geological conditions are required for standing column wells?

Standing column wells require solid, consolidated bedrock (such as granite, basalt, or limestone) that does not cave in when unlined, as well as adequate natural aquifer recharge.