💧 Monitair 75 Through-Wall Dehumidifier with Defrost – DH75AX/T (Single Phase)

Transform your indoor pool environment with the most space-efficient dehumidifier solution available

The Monitair 75 (DH75AX/T) is a professional-grade through-wall dehumidifier engineered specifically for indoor swimming pools, therapy centres, health clubs, and hotel spa facilities. By extracting up to 86.4 litres of moisture per day while recovering latent heat energy, this unit protects your building structure while dramatically reducing energy costs compared to traditional ventilation-only systems.

Why Choose the Monitair 75 Through-Wall Dehumidifier?

🏊 Space-Saving Through-Wall Design

Unlike traditional wall-mounted units that consume valuable pool hall space, the DH75AX/T installs through the wall with only decorative inlet/outlet grilles visible in your pool area. The entire unit sits in an adjacent plant room or utility space, providing powerful dehumidification without compromising your pool hall aesthetics or floor space.

⚡ Intelligent Heat Recovery Technology

The Monitair 75 doesn’t just remove moisture – it captures the latent heat energy locked in water vapour and converts it into 4.7kW of usable warmth, returning it directly to your pool hall. This recovered heat helps maintain comfortable temperatures, reduces boiler runtime, and minimizes evaporation from your pool surface.

❄️ Advanced Defrost System

Equipped with automatic defrost capability, the DH75AX/T maintains consistent performance even when operating in cooler conditions down to 5°C. This ensures year-round reliability without manual intervention or performance degradation during winter months.

💰 Exceptional Running Cost Efficiency

With a nominal power consumption of just 1.46kW while delivering 4.7kW of heat output through energy recovery, the Monitair 75 achieves a remarkable efficiency ratio. By minimizing the need to introduce and heat cold outdoor air for dehumidification, you’ll see substantial reductions in your heating bills.

🔧 Professional-Grade Build Quality

Manufactured by Calorex (Certikin), a leading name in pool environment control, the DH75AX/T features R407C ozone-friendly refrigerant, corrosion-resistant construction suitable for high-humidity environments, and comes with a comprehensive 2-year manufacturer’s warranty supported by a nationwide network of service engineers.

Complete Technical Specifications

Dehumidification Performance

Electrical Requirements

Physical Dimensions & Installation

Wall Penetration Requirements

Acoustic Performance

Important Installation Note: Machine and duct must be sealed to wall with all cavities filled to prevent recirculation. For cavity wall installations, seal around both supply and intake holes with non-porous sleeves or boards.

Optional LPHW Air Heating Upgrade

The DH75AX/TL variant includes a Low Pressure Hot Water (LPHW) air heating battery that provides supplementary space heating, eliminating the need for separate fan heaters or radiators.

LPHW Heating Specifications (DH75AX/TL Only)

Note: LPHW heating requires boiler water supply at 80°C. Performance figures assume pool water at 28°C and pool hall air at 30°C / 60% RH.

Room Size & Coverage Recommendations

Suitable Pool Hall Volumes

Pool Surface Area Guidelines

Calculation basis: Assumes pool water temperature 28°C, pool hall air 30°C at 60% RH, with pool cover used when not in use.

Real-World Performance & Moisture Removal Times

Estimated Dehumidification Times

Understanding how quickly the Monitair 75 can reduce humidity levels helps with operational planning:

Important Disclaimers:

• Times are estimates assuming continuous operation at 30°C ambient temperature
• Actual performance varies based on external air infiltration, pool cover usage, bather load, and ambient conditions
• Initial moisture removal is faster; times increase as target humidity approaches
• Using a pool cover when the pool is not in use significantly reduces dehumidification requirements

Daily Moisture Extraction Capacity

At 86.4 litres per day, the Monitair 75 can handle typical moisture generation from:

• Indoor pool up to 50m² with moderate use (4-6 hours daily)
• Therapy pool with continuous use up to 35m²
• Spa facility pool area with intermittent high occupancy

Energy Efficiency & Running Cost Analysis

Efficiency Advantage Over Ventilation-Only Systems

Traditional dehumidification using outdoor air ventilation requires heating that cold air to pool hall temperature – an energy-intensive process. The Monitair 75’s heat recovery system offers substantial savings:

*Based on typical indoor pool operating 8 hours/day, 6 days/week at £0.24/kWh electricity rate

Heat Recovery Explained

For every 1 kW of electricity consumed, the Monitair 75 delivers 3.2 kW of effective heating through energy recovery – a coefficient of performance (COP) of 3.2:1. This recovered heat:

• ✅ Reduces boiler runtime by 30-50%
• ✅ Maintains comfortable air temperature naturally
• ✅ Reduces pool surface evaporation by maintaining optimal air temperature
• ✅ Lowers overall HVAC system load

Installation Requirements & Clearances

Through-Wall Installation Overview

The Monitair 75 through-wall model requires careful planning for optimal performance:

✅ What’s Included:

• Full wall mounting brackets and fixings
• Decorative internal grilles for supply and intake ducts
• Duct sleeves for wall penetration
• Installation manual with detailed specifications

🔧 Installation Prerequisites:

• Wall thickness: Suitable for standard cavity walls (275-350mm typical)
• Plant room depth: Minimum 400mm clearance behind unit
• Wall penetrations: Two rectangular openings as per specifications
• Electrical supply: Dedicated 13A circuit with motor-rated fuse
• Condensate drainage: 15mm waste connection with fall

Minimum Clearances Required

Plant Room Considerations

⚠️ Critical for Through-Wall Models:

• Plant room must NOT connect to pool hall air space (prevent recirculation)
• Adequate plant room ventilation required for compressor heat dissipation
• Floor must support 153 kg unit weight plus mounting brackets
• Access for future maintenance and component replacement essential

Key Features at a Glance

🎯 Top 7 Standout Benefits

1. Space Liberation Install the entire unit in your plant room while enjoying powerful dehumidification in your pool hall. Only attractive grilles visible – no bulky wall-mounted equipment consuming valuable space.

2. Free Heat Recovery Captures 4.7kW of heat from extracted moisture and returns it to your pool hall. This “free” heating reduces boiler dependency and creates a naturally comfortable environment.

3. Automatic Defrost Protection Operates reliably down to 5°C without performance loss. The defrost system automatically activates when needed, ensuring consistent moisture removal year-round.

4. Whisper-Quiet Operation At just 48.5 dB(A) at 3 metres, the Monitair 75 runs quieter than normal conversation. Through-wall design further reduces perceived noise in the pool hall.

5. Professional Reliability Built to commercial standards with corrosion-resistant materials. Backed by Calorex/Certikin’s reputation for pool environment control excellence and a 2-year comprehensive warranty.

6. Intelligent Humidity Control Variable humidistat adjustable from 20-80% RH allows precise control. Set your ideal comfort level and the unit maintains it automatically.

7. Structural Protection Prevents costly moisture damage to building structures, protects expensive finishes, and inhibits mould and bacteria growth by maintaining optimal humidity levels.

How Heat Recovery Dehumidification Works

The Monitair 75 uses advanced refrigeration technology to simultaneously remove moisture AND generate heat:

Step 1: Warm, humid air from your pool hall is drawn through the intake grille

Step 2: Air passes over a cold evaporator coil where moisture condenses into water

Step 3: Dry air then passes over a hot condenser coil, gaining heat from the refrigeration cycle

Step 4: Warm, dry air returns to the pool hall via the supply grille

Step 5: Condensed water drains away via 15mm drain connection

The Result: Your pool hall receives warmer, drier air while consuming minimal electricity. The energy that was “locked” in the moisture is recovered and used beneficially rather than wasted.

Installation Scenarios & Applications

Ideal For:

✅ Domestic Indoor Pools Perfect for home pool installations up to 10m × 5m where space is at a premium and plant room installation is feasible.

✅ Therapy & Rehabilitation Pools Maintains clinical standards for moisture control while providing quiet, unobtrusive operation suitable for therapeutic environments.

✅ Boutique Hotel & Spa Pools Space-saving design preserves aesthetics while delivering professional-grade humidity control. Quiet operation doesn’t disturb guests.

✅ Health Club Small Pools Suitable for teaching pools, hydrotherapy pools, or smaller fitness facility pools up to 50m² surface area.

✅ Existing Pool Retrofits Through-wall design ideal for adding professional dehumidification to existing pools where internal space cannot accommodate wall-mounted units.

When to Consider Upgrading to Monitair 110:

• Pool surface area exceeds 60 m²
• Pool hall volume over 500 m³
• Heavy commercial use with high bather loads
• Multiple water features (spa, splash zones, etc.)
• Inadequate performance from current equipment

Comparison: Standard vs Through-Wall Models

Recommendation: Choose through-wall (DH75AX/T) when you have access to suitable plant room space and want to maximize pool hall aesthetics and usable space.

Maintenance & Operating Guidelines

Routine Maintenance Requirements

Monthly Tasks:

• ✅ Inspect and clean inlet/outlet grilles (remove lint, debris)
• ✅ Check condensate drain is flowing freely
• ✅ Verify humidistat settings are appropriate for season

Quarterly Tasks:

• ✅ Clean or replace washable air filters
• ✅ Inspect condensate drain trap (ensure water seal present)
• ✅ Check for any unusual noises or vibrations

Annual Service:

• ✅ Professional inspection by qualified technician
• ✅ Refrigerant pressure check
• ✅ Electrical connection inspection
• ✅ Compressor and fan motor condition assessment
• ✅ Deep clean of evaporator and condenser coils

Maximizing Efficiency & Lifespan

💡 Pro Tips for Optimal Performance:

1. Use a Pool Cover: Reduces evaporation by 90% when pool not in use, dramatically reducing dehumidifier workload
2. Maintain Pool Water Temperature: Keep at 28°C or below; higher temperatures increase evaporation exponentially
3. Limit Air Temperature: Maintain pool hall at 30°C maximum; excessive heat increases moisture generation
4. Ensure Good Air Circulation: Don’t block inlet or outlet grilles; maintain specified clearances
5. Address Air Leaks: Seal external doors and windows to prevent humid outdoor air infiltration
6. Monitor Performance: If unit runs continuously without achieving target humidity, investigate causes (air leaks, excessive pool temperature, etc.)

Troubleshooting Common Issues

⚠️ Important: If unit requires refrigerant work, compressor service, or electrical repairs, always use a qualified F-Gas certified technician.

Frequently Asked Questions

❓ What size pool can the Monitair 75 handle effectively?

The DH75AX/T is suitable for indoor pools with surface areas up to approximately 50-60m² (typical dimensions 10m × 5m to 12m × 5m). This assumes pool water at 28°C, pool hall at 30°C, and sensible use of a pool cover when not in use. For larger pools, consider the Monitair 110 model with 4.5L/hr capacity.

❓ Can I install this unit myself or do I need a professional?

Professional installation is strongly recommended. The through-wall installation requires structural wall penetration, proper sealing to prevent air recirculation, electrical connection by a qualified electrician, and correct condensate drainage setup. Improper installation can significantly reduce performance and void warranty coverage.

❓ How much does the Monitair 75 cost to run per month?

Based on typical operation (8 hours daily, 6 days/week) at current electricity rates around £0.24/kWh, expect monthly running costs of approximately £140-180. Actual costs vary with usage patterns, ambient conditions, and local electricity rates. The heat recovery function substantially reduces overall heating costs, often saving £140-240 monthly compared to ventilation-only dehumidification.

❓ Is the unit noisy? Will it disturb swimmers?

The Monitair 75 operates at 48.5 dB(A) measured at 3 metres – comparable to quiet conversation or a modern refrigerator. The through-wall design further reduces noise perception in the pool hall since the compressor and fan are located in the adjacent plant room rather than within the pool space itself.

❓ What’s the difference between the DH75AX/T and DH75AX/TL models?

The “L” designation indicates the model includes an LPHW (Low Pressure Hot Water) air heating battery. The standard DH75AX/T provides 4.7kW of heat through energy recovery only. The DH75AX/TL adds an 8.9kW LPHW heating coil (requires connection to your boiler system), delivering up to 11.3kW total heat output – useful for larger spaces or when supplementary heating is needed.

❓ How often do filters need cleaning or replacement?

The washable air filters should be inspected monthly and cleaned quarterly under normal conditions. More frequent cleaning may be required if your pool hall has high dust levels or heavy usage. The filters are easily accessible behind the internal grilles and can be cleaned with warm soapy water, rinsed, and reinstalled once dry.

❓ Can this unit cool the pool hall in summer?

No, the Monitair 75 is a dehumidifier with heat recovery – it adds heat to the space. For summer cooling, you would need to implement natural ventilation, mechanical ventilation, or a separate air conditioning system. Some facilities simply open windows/doors for natural ventilation during hot weather when the pool hall might otherwise overheat.

❓ What happens if there’s a power cut?

The unit will stop operating during a power outage. Once power is restored, most models will automatically restart based on the humidistat setting. However, during extended outages, pool hall humidity will rise significantly. This highlights the importance of robust construction materials (as detailed in the Pool Hall Construction Guidelines PDF) that can withstand temporary periods of high humidity without damage.

❓ How long does the unit typically last?

With proper annual maintenance, the Monitair 75 typically provides 10-15 years of reliable service. Key factors affecting lifespan include maintenance regularity, water chemistry control (chlorine vapours can be corrosive), ambient operating conditions, and duty cycle. The 2-year manufacturer’s warranty covers parts and labour, and extended warranty options may be available through your installer.

❓ Do I need the defrost version, or can I save money without it?

Defrost is standard on all Monitair models operating in UK conditions and should not be skipped. Even in well-insulated, heated pool halls, ambient temperatures can drop below 10°C during winter, especially during startup or overnight. The defrost system prevents ice buildup on the evaporator coil that would severely degrade performance.

❓ What wall thickness is required for through-wall installation?

The through-wall model is designed for standard UK cavity walls ranging from 275-350mm thickness. For walls outside this range, consult with your installer – telescopic mounting options or custom fabricated extensions may be available. The unit depth is 350mm, and adequate clearance must be provided on the plant room side.

❓ Can I connect this to a building management system (BMS)?

Standard models include basic control via the adjustable humidistat. For integration with BMS systems or remote monitoring, consult with Calorex technical support or your installer about available interface options. Some installations may require additional control panels or relay interfaces.

📄 Downloads & Technical Documentation

Access comprehensive technical information, installation guides, and design resources:

Product Datasheets & Specifications

📄 Vaporex and Monitair Range Brochure 2022 (opens in new tab) Complete technical specifications for the entire Monitair dehumidifier range including DH75AX/T model. Includes performance data, dimensional drawings, electrical requirements, and model comparison charts. Essential reading before purchase. (PDF, 4 pages)

📄 Monitair 110 Technical Specifications (opens in new tab) Detailed specifications for the larger Monitair 110 model. Useful for comparison if you’re deciding between the 75 and 110 capacity models, or planning for future expansion. Includes dimensional drawings and through-wall installation details. (PDF, 2 pages)

Installation & Design Guidelines

📄 Guidelines to Pool Hall Construction 2022 (opens in new tab) Comprehensive guide to designing and building indoor pool environments. Covers insulation requirements, vapour barriers, structural considerations, glazing recommendations, and dehumidification principles. Essential reading for architects, builders, and pool owners planning new construction or major renovations. (PDF, 8 pages)

💡 Installer Note: All PDF documents open in a new browser tab. Save these documents for reference during planning, installation, and maintenance phases.

Why Buy From Parts4Tubs?

✅ Expert Technical Support – Knowledgeable staff to help with product selection and sizing

✅ Installation Guidance – Can recommend qualified installers in your area

✅ Competitive Pricing – Professional equipment at fair prices

Ready to Transform Your Pool Environment?

The Monitair 75 Through-Wall Dehumidifier represents the optimal solution for indoor pools where space is valuable, energy efficiency matters, and professional-grade performance is required. With its heat recovery technology, whisper-quiet operation, and space-saving design, it’s the smart choice for protecting your investment while creating the perfect pool environment.

Need help deciding if this is the right unit for your application? Contact our technical team with your pool dimensions, hall volume, and any specific requirements. We’ll provide honest guidance on whether the Monitair 75 meets your needs or if a different model would be more appropriate.

Important Purchasing Note: This product is supplied as the dehumidifier unit only. Professional installation, electrical connection, wall penetration work, and condensate drainage installation are not included and must be arranged separately. We recommend working with qualified pool environment specialists familiar with Calorex equipment.