---
title: "Case Study: Exploiting Lake Energy for Efficient Heating in Main Ridge"
date: 2025-02-12T15:25:00+11:00
author: Geoff Pennington
canonical_url: "https://sogeo.com.au/case-studies/case-study-exploiting-lake-energy-for-efficient-heating-in-main-ridge"
section: Pages
---
![Stiebel Eltron Geothermal Hydronic Heat Pump By SoGeo]()

#  Case Study: Exploiting Lake Energy for Efficient Heating in Main Ridge 

Discover how SoGeo transformed a residential heating system in Main Ridge, VIC, by leveraging a natural lake as a geothermal heat source. Learn how sustainable solutions can enhance comfort and reduce energy costs.

 

 

 

 SóGeo was engaged by Grant in Main Ridge, VIC, to upgrade an existing heating system on his residential property. The home already had hydronic underfloor heating; we set out to lift its efficiency by tapping a resource on the property the existing system was ignoring - a spring-fed lake.

SóGeo installed a 15kW Stiebel Eltron geothermal heat pump (GSHP) drawing from the lake as its heat source — a project also featured on the [**Stiebel Eltron project showcase**](https://www.stiebel-eltron.com.au/projects/main-ridge-geothermal?hsLang=en-au). The lake-loop design significantly reduced installation cost compared to a vertical-borehole geo-exchange while improving overall system performance.

Lake-Loop Geothermal Design

The spring-fed lake maintains a consistent winter temperature of around 8°C - a stable, mild source the heat pump can draw from year-round. That stability is what drove the system’s strong Seasonal Coefficient of Performance (SCOP), at a fraction of the installation cost of a traditional vertical-borehole geo-exchange.

Tight Plant Room Constraints

The existing plant room was small and packed with outdated, energy-intensive pumps. To work within those constraints, we specified a custom wall-mounted buffer tank from Germany- it used wall area that floor-mount tanks couldn’t, freeing up the limited floor space. We replaced the existing fixed-speed underfloor circulation pumps with modern EC (electronically commutated) units - higher efficiency, finer control, and the ability to modulate alongside the heat pump’s variable output.

Installation

The full install was handled in-house by the SóGeo team in one week. No external contractors needed.

Measured Performance

The system achieved an SCOP of 5.1 - strong, particularly given the design conditions. The lake source averages around 8°C in winter. On the load side, the existing underfloor circuit (pipe pitched at 200–250mm in concrete slab) required a flow temperature of 50–55°C to meet the home’s heat loss requirement. That’s a higher lift than a typical underfloor design, and the lake-source stability is what kept overall efficiency strong despite it.

Client Feedback

Grant has been pleased with the result — measurable reduction in electricity bills, and even, predictable heating across the home.

Key Takeaways

\- Where a site has a suitable body of water at stable temperature, a lake-loop geo-exchange is a viable, lower-cost alternative to vertical-borehole drilling.  
\- Custom wall-mounted buffer tanks can resolve plant-room space constraints that would otherwise force compromise on system sizing.  
\- Replacing fixed-speed circulation pumps with modern EC units lifts efficiency and gives the heat pump’s controls a finer instrument to modulate with.

 

 

## Our Partners

   [ ![Reece](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/Reece.png) ](https://www.reece.com.au/)   [ ![Stiebel Eltron](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/Stiebel-Eltron.png) ](https://www.stiebel-eltron.com.au/)   [ ![Mitsubishi](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/Mitsubishi.png) ](https://www.mitsubishielectric.com.au/)   [ ![Purmo](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/Purmo.png) ](https://www.purmo.com/au)   [ ![Viessmann](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/viessmann_wordmark_rgb_1_vitorange.png) ](https://www.viessmann.com.au/)