🔥 Bowman GL140 Heat Exchanger 1,000,000 BTU (300kW) – Cupro Nickel | 3708-2C

🌡️ High-Capacity Commercial Pool Heating – Engineered for Large-Scale Aquatic Facilities with Triple-Speed Heat Transfer Technology

📋 Product Overview

The Bowman GL140-3708-2C is a high-performance cupro nickel heat exchanger engineered for large commercial and institutional swimming pools. Part of Bowman’s renowned GL series, this unit delivers an impressive 300kW (1,000,000 BTU/hr) heat transfer capacity when paired with an 82°C boiler system, making it ideal for Olympic-sized pools and major aquatic centres.

Bowman’s unique tube design delivers up to three times faster heating than standard competitor units, significantly reducing energy costs and heat-up times. The cupro nickel construction provides excellent corrosion resistance for chlorinated pool water, while the removable tube stack design ensures straightforward maintenance access throughout the unit’s long service life.

Suitable for pools up to 455,000 litres (100,000 gallons), this heat exchanger represents over 100 years of British heat transfer engineering expertise. Whether connected to a boiler system, heat pump, or integrated into a multi-source heating arrangement, the GL140-3708-2C delivers consistent, reliable performance for demanding commercial applications.

⭐ Key Features

✅ Exceptional Heat Output – Delivers 300kW (1,000,000 BTU/hr) with 82°C boiler water, or 170kW (580,000 BTU/hr) with 60°C systems

✅ Cupro Nickel Tube Stack – Superior corrosion resistance for chlorinated pool water with excellent heat transfer properties

✅ Triple-Speed Heating Technology – Bowman’s optimised tube design heats pools up to three times faster than standard units

✅ High Flow Capacity – Accommodates pool water flow rates up to 50.4m³/h (840 l/min) for large-scale installations

✅ Commercial-Grade Construction – Heavy-duty cast iron body with industrial BSP threaded connections

✅ Flexible Mounting Options – Can be installed vertically or horizontally to suit your plant room configuration

✅ Easy Maintenance Access – Removable end covers and tube stack for simple cleaning and servicing

✅ Integral Thermostat Pocket – Built-in 7mm thermostat pocket for accurate pool water temperature monitoring

✅ Wide System Compatibility – Works with boilers, heat pumps, solar thermal systems, and combined heat sources

✅ Proven Reliability – Backed by Bowman’s 100+ years of heat transfer expertise and worldwide installations

🔧 Technical Specifications

Specification	Details
Model Number	GL140-3708-2C
Heat Output (82°C Boiler)	300 kW / 1,000,000 BTU/hr
Heat Output (60°C Boiler)	170 kW / 580,000 BTU/hr
Shell Material	Cast Iron
Tube Stack Material	Cupro Nickel
Maximum Pool Volume	455 m³ / 100,000 gallons
Boiler/Primary Flow Rate	12.6 m³/h (210 l/min)
Maximum Pool Water Flow	50.4 m³/h (840 l/min)
Max Operating Pressure	6 bar (both sides)
Max Operating Temperature	110°C (heating side) / 100°C (pool side)
Pool Water Connections	3″ BSP Threaded
Boiler Water Connections	1½” BSP Threaded
Overall Length	532 mm
Shell Diameter	162 mm
Mounting Hole Spacing	120 mm x 100 mm (M10 x 15)
Weight (Dry)	30 kg
Thermostat Pocket	Integral 7mm diameter
Warranty	12 months (manufacturing faults)

📊 Heat Transfer Performance

🏊 Pool Heating Capacity

The GL140-3708-2C delivers substantial heat transfer performance optimised for commercial pool applications:

With 82°C Boiler Water:

• Heat Output: 300 kW (1,000,000 BTU/hr)
• Suitable for pools up to: 455,000 litres (100,000 gallons)
• Boiler Flow Required: 12.6 m³/h (210 l/min)

With 60°C Boiler Water:

• Heat Output: 170 kW (580,000 BTU/hr)
• Suitable for pools up to: 455,000 litres (100,000 gallons)
• Boiler Flow Required: 12.6 m³/h (210 l/min)

⚡ Efficiency Factors

• Counter-Flow Design – Must be installed with pool water flowing opposite to heating water for optimal performance
• Flow Rate Optimisation – Performance figures based on achieving 30°C pool water temperature
• Proper Sizing – Ensure boiler/heat source capacity matches heat exchanger requirements
• Temperature Differential – Greater differential between heating source and pool water increases heat transfer rate

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⏱️ Heat-Up Times & Temperature Maintenance

⚠️ Important Notice: Heat-up times vary significantly based on multiple factors including:

• Heat source output (boiler/heat pump kW rating)
• Starting water temperature
• Target water temperature
• Pool cover usage
• Ambient/outdoor temperature
• Heat exchanger sizing match
• Pool insulation quality
• Weather conditions

The GL140-3708-2C is a passive heat transfer device – actual heating times depend entirely on your heat source capacity and installation conditions.

📐 Sizing Guidance from Manufacturer

According to Bowman’s technical documentation, the GL140-3708-2C is rated for:

• Maximum Pool Volume: 455 m³ (100,000 gallons) with 82°C boiler water
• Performance Basis: All ratings calculated to achieve 30°C pool water temperature

🛡️ Material & Compatibility Guide

Cupro Nickel Construction – The GL140-3708-2C Choice

The cupro nickel tube stack in this model offers an excellent balance of performance and durability:

✅ Chlorinated Freshwater Pools – Ideal for standard chemically-treated pool water

✅ Excellent Heat Transfer – Cupro nickel provides superior thermal conductivity

✅ Strong Corrosion Resistance – Withstands typical pool chemical levels

✅ Cost-Effective Durability – Long service life at competitive pricing

✅ Proven Performance – Trusted material choice for commercial installations

📋 Recommended Water Chemistry Limits (Cupro Nickel)

Parameter	Recommended Range
Free Chlorine	1.0 – 3.0 ppm
pH Level	7.2 – 7.8
Calcium Hardness	200 – 400 ppm
Alkalinity	100 – 150 ppm
Bromine	2.0 – 4.0 ppm
Chloride	Less than 150 ppm

⚠️ Material Selection Notes

• Salt Water Pools: For salt water chlorinator systems or salt water pools, consider the GL140-3708-2T (Titanium) variant
• Freshwater Only: Stainless steel models should NOT be used with salt water chlorinators or salt water pools
• Titanium Option: Available as GL140-3708-2T with 10-year tube stack guarantee and suitability for all water types

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🎯 Applications & Use Cases

The Bowman GL140-3708-2C is engineered for demanding commercial applications:

🏢 Commercial & Institutional Facilities

• Large leisure centres and aquatic complexes
• Olympic and competition swimming pools
• Multi-pool commercial facilities
• Hotel and resort pool systems

🏊‍♂️ Aquatic Centres

• Public swimming pools
• Council-operated facilities
• School and university pools
• Sports training centres

🔥 Heat Source Integration

• Boiler Systems – Designed for optimal performance with gas, oil, or biomass boilers
• Heat Pump Connection – Compatible with air-source and ground-source heat pump systems
• Combined Systems – Integrates seamlessly into multi-source heating arrangements

🏭 Industrial Applications

• Process water heating
• Large-scale water temperature control
• Industrial facility pools

🔨 Installation Considerations

Mounting Options

• Vertical Mounting – Space-saving configuration for compact plant rooms
• Horizontal Mounting – Traditional installation with easy access to connections

Critical Installation Requirements

⚠️ Counter-Flow Configuration Required The heat exchanger MUST be installed in counter-flow arrangement – pool water must flow in the opposite direction to heating water. Failure to install correctly will significantly reduce performance.

⚠️ Thermostat Positioning Install the thermostat in the integral pocket on the pool water INLET side for accurate temperature monitoring.

Connection Specifications

• Pool Water: 3″ BSP threaded connections
• Boiler/Heat Source: 1½” BSP threaded connections
• Thread Engagement: Ensure sufficient thread engagement with the C-Coat 300 coated internal threads

Installation Best Practices

✅ Install downstream of pumping and filtration equipment

✅ Use pump-assisted boiler/solar water circulation

✅ Fit isolation valves on all connections for maintenance access

✅ Install dosing systems AFTER the heat exchanger with non-return valve

✅ Add inhibitor to boiler circuit for corrosion protection

✅ Ensure frost-free installation location

✅ Allow adequate access for end cover removal and maintenance

⚠️ Professional Installation Recommended – For warranty compliance and optimal performance, professional installation by a qualified engineer is strongly recommended.

📥 Downloads & Resources

 Swimming Pool Heat Exchanger Brochure – Complete product range specifications and performance data (PDF)

 Installation, Operation & Maintenance Guide – Full technical installation instructions and maintenance procedures (PDF)

🏆 Why Choose Bowman Heat Exchangers

✅ 100+ Years of British Engineering Excellence – EJ Bowman has manufactured heat exchangers in Birmingham, UK since 1920

✅ World-Leading Pool Heat Exchangers – Tens of thousands of units operating reliably worldwide, from domestic spas to Olympic facilities

✅ Superior Heat Transfer Design – Up to three times faster heating than competitor products through optimised tube design

✅ Quality Materials & Construction – Premium cupro nickel, stainless steel, and titanium options to suit every application

✅ Proven Global Track Record – Trusted by major aquatic facilities including the Sochi Winter Olympics venue and Nirvana Spa

✅ Comprehensive Support – Full range of spare parts available with detailed technical documentation

✅ Material Guarantees – Titanium tube stacks carry a full 10-year guarantee on all titanium in contact with pool water

🛍️ Why Buy from Parts4Tubs

✅ UK-Based Pool Heating Specialists – Expert knowledge of commercial and domestic pool heating solutions

✅ Authorised Bowman Stockist – Genuine products with full manufacturer warranty

✅ Technical Advice Available – Our team can help with sizing, selection, and installation queries

✅ Fast UK Delivery – Quick dispatch on in-stock items

✅ Competitive Pricing – Trade and volume discounts available

✅ After-Sales Support – Spare parts, servicing advice, and ongoing technical support

✨ Summary

The Bowman GL140-3708-2C represents the pinnacle of commercial pool heat exchanger technology. With 300kW heat transfer capacity, robust cupro nickel construction, and Bowman’s renowned triple-speed heating design, this unit delivers exceptional performance for pools up to 455,000 litres. Backed by over a century of British engineering expertise and trusted by aquatic facilities worldwide, the GL140 is the professional choice for large-scale pool heating applications.

Ready to heat your commercial pool efficiently? Contact Parts4Tubs today for expert advice and competitive pricing.