💨 Monitair 75 Dehumidifier with Defrost (1 Phase) | DH75AX

Transform Your Indoor Pool Environment with Professional-Grade Humidity Control

The DH75AX Monitair 75 is a high-performance, non-ducted dehumidifier specifically engineered for indoor swimming pool environments. Whether you manage a domestic pool, therapy center, health club, hotel spa, or leisure facility, this advanced system delivers exceptional moisture control while recovering energy to reduce running costs and protect your building investment.

Why the Monitair 75 Stands Above the Rest

Indoor swimming pools create challenging atmospheric conditions. Without proper humidity control, moisture damage leads to corrosion of structural elements, mold growth, bacteria proliferation, and accelerated deterioration of building materials. The Monitair 75 doesn’t just remove moisture—it intelligently converts the latent energy trapped in water vapor into usable heat, creating a warm, dry, and healthy environment while dramatically reducing your energy bills.

🌟 Key Features & Benefits

✅ High-Capacity Dehumidification – Removes up to 3.6 litres per hour (86.4 litres per day) at optimal conditions, effectively managing humidity in medium to large indoor pool halls

✅ Advanced Defrost System (Standard) – Maintains consistent performance even in cooler conditions, operating reliably down to 5°C ambient temperature

✅ Energy Recovery Technology – Recovers 4.7 kW of heat from moisture extraction, contributing to space heating and reducing boiler dependency

✅ Optional LPHW Air Heating – Available with Low Pressure Hot Water heating battery (8.9 kW additional heat output) to eliminate the need for separate radiators or fan heaters

✅ Flexible Installation Options – Choose between wall-mounted or through-wall (TTW) configurations to suit your space and aesthetic requirements

✅ Single-Phase Operation – Easy integration with standard 230V/50Hz electrical supply—no three-phase power needed

✅ Variable Humidistat Control – Adjustable humidity settings from 20% to 80% RH for precise environmental management

✅ Quiet Operation – Only 48.5 dB(A) at 3 meters, ensuring a peaceful pool environment

✅ Robust Build Quality – Smooth white coated alloy finish, designed for long-term durability in corrosive pool hall atmospheres

✅ 2-Year Manufacturer’s Warranty – Full parts and labour coverage backed by nationwide service engineer support

📊 Complete Technical Specifications

Dehumidification Performance

Specification	DH75AX (Wall Mount)	DH75AX/T (Through Wall)
Model Number	DH75AX	DH75AX/T
Dehumidification Capacity	3.6 L/hr (86.4 L/day)	3.6 L/hr (86.4 L/day)
Air Flow Rate	1,180 m³/hr	1,180 m³/hr
Heat Recovery Output	4.7 kW	4.7 kW
Operating Temperature Range	Down to 5°C (with defrost)	Down to 5°C (with defrost)
Humidistat Range	20% to 80% RH (adjustable)	20% to 80% RH (adjustable)
Refrigerant Type	R407C (ozone friendly)	R407C (ozone friendly)

Performance figures based on pool water at 28°C, air at 30°C and 60% RH

Optional Air Heating Specifications (LPHW Models)

Specification	DH75AX/L	DH75AX/TL
LPHW Heat Output	8.9 kW	8.9 kW
Total Heat (Recovery + LPHW)	11.3 kW	11.3 kW
LPHW Flow Rate	9.6 L/min	9.6 L/min
LPHW Pressure Drop	2.8 m head	2.8 m head
LPHW Connection Size	22mm copper stub	22mm copper stub
Boiler Temperature	80°C (recommended)	80°C (recommended)

Electrical Specifications

Specification	Value
Electrical Supply	230V / 50Hz (Single Phase)
Nominal Power Consumption	1.46 kW
Nominal Running Current	6.4 Amps
Full Load Amps (FLA)	7.8 Amps
Compressor LRA	55 Amps
Fuse Rating Required	13 Amp (motor rated)

Physical Dimensions & Installation

Dimension	Wall Mount Model	Through Wall Model
Width (unpacked)	1,520 mm	1,474 mm
Height (unpacked)	796 mm	1,167 mm (to top duct)
Depth (unpacked)	385 mm	350 mm
Weight (unpacked)	153 kg	153 kg
Condensate Drain	15mm diameter stub	15mm diameter stub

Acoustic Performance

Specification	Value
Noise Level at 3m	48.5 dB(A)

⚠️ Note: Through-wall models include duct and decorative grille kit for professional installation

🏊 Suitability Guide: Is the Monitair 75 Right for Your Pool?

Recommended Pool Hall Volumes

The DH75AX is designed for medium to large indoor pool environments. Based on its 3.6 L/hr dehumidification capacity and 1,180 m³/hr air circulation rate, this unit is ideally suited for:

Pool Hall Volume	Suitability	Notes
Up to 300 m³	✅ Excellent	Ideal capacity with headroom for peak demand
300-450 m³	✅ Good	Well-suited for typical conditions
450-600 m³	⚠️ Adequate	May require supplementary ventilation during high bather loads
Over 600 m³	❌ Undersized	Consider Monitair 110 or multiple units

Typical Applications

✅ Domestic Indoor Pools – Private residential pool halls up to 10m x 5m

✅ Therapy Pools – Rehabilitation and hydrotherapy facilities

✅ Small Hotel Pools – Boutique hotel and B&B pool facilities

✅ Health Club Pools – Small to medium fitness center pools

✅ Spa Facilities – Wellness centers and spa pool areas

✅ School Swimming Pools – Small teaching pools and learn-to-swim facilities

💰 Energy Efficiency & Running Cost Benefits

How Energy Recovery Works

Unlike basic dehumidifiers that simply remove moisture and waste the energy, the Monitair 75 uses heat pump technology to recover latent heat from water vapor. This recovered energy (4.7 kW) is returned to your pool hall as warm, dry air—effectively providing free heating.

Real-World Cost Savings

Traditional Method (Ventilation Only):

• Brings in cold outdoor air that must be heated from scratch
• High energy consumption for space heating
• Estimated running cost: £4-6 per hour during winter

Monitair 75 Method (Heat Recovery):

• Recycles and recovers energy from moist air
• Minimal additional heating required
• Estimated running cost: £1.20-1.80 per hour for the unit alone
• Potential savings: 50-70% on space heating costs

💡 Annual Savings Estimate: For a pool hall operating 10 hours daily, year-round energy recovery could save £3,000-£5,000 annually compared to ventilation-only humidity control.

Estimates based on electricity at £0.30/kWh and gas at £0.07/kWh

⏱️ Dehumidification Performance: Real-World Scenarios

Moisture Extraction in Different Conditions

The Monitair 75’s 3.6 L/hr capacity is measured at optimal conditions (30°C, 60% RH). Here’s how performance varies:

Pool Hall Condition	Relative Humidity	Estimated Extraction Rate	Time to Reduce RH by 10% (300m³ hall)*
Hot & Humid (After Heavy Use)	70-80% RH	4.0-4.5 L/hr	2-3 hours
Optimal Operating Conditions	60-70% RH	3.6-4.0 L/hr	3-4 hours
Moderate Humidity	50-60% RH	3.0-3.5 L/hr	4-5 hours
Lower Humidity (Cooler Days)	40-50% RH	2.5-3.0 L/hr	5-6 hours

Estimates assume minimal fresh air infiltration and average bather load

Maintaining Ideal Pool Hall Conditions

The recommended relative humidity for indoor pool halls is 50-60% RH at 28-30°C air temperature. The Monitair 75 continuously monitors humidity via its built-in humidistat and cycles automatically to maintain your set point, ensuring:

✅ Comfortable swimming conditions ✅ Minimal condensation on windows and surfaces ✅ Protected building structure ✅ Reduced chloramine buildup

🔧 Installation Guidance & Options

Wall-Mounted Installation (DH75AX)

Best For: Pool halls with adequate wall space and where aesthetics are a priority

Installation Requirements:

• Suitable wall structure capable of supporting 153 kg
• Access to 230V electrical supply with 13A motor-rated fuse
• 15mm condensate drainage to waste (gravity or pumped)
• Minimum clearances: 300mm sides, 500mm top, 200mm bottom
• Variable air outlet grille positioning for optimal air distribution

Advantages:

• Compact footprint (1,520mm W x 796mm H x 385mm D)
• All equipment visible for easy maintenance
• Direct air circulation into pool hall

Through-Wall Installation (DH75AX/T)

Best For: Situations where equipment must be located in an adjacent plant room

Installation Requirements:

• Two rectangular penetrations through wall (dimensions: 892mm x 382mm intake, 984mm x 346mm supply)
• Plant room must be within immediate adjacency to pool hall
• Supplied with decorative inlet and outlet grilles
• Wall thickness accommodation: standard installation, sleeves available for thicker walls
• Unit must be fully sealed to wall to prevent air recirculation

Advantages:

• Cleaner pool hall aesthetics (only grilles visible)
• Quieter operation (equipment noise contained in plant room)
• Easier maintenance access from plant room
• Protects unit from direct pool hall moisture exposure

⚠️ Critical Installation Note: For through-wall installations, all cavities around supply and intake holes must be sealed with non-porous sleeves/boards to prevent short-circuit air recirculation, which would severely compromise performance.

🛠️ Optional LPHW Air Heating System

When to Specify the “L” Heating Option

If your pool hall requires additional space heating beyond the heat recovery provided by dehumidification alone, the DH75AX/L models integrate a Low Pressure Hot Water (LPHW) heating battery.

Benefits of Integrated Air Heating: ✅ Eliminates need for separate radiators or fan heaters ✅ Single equipment solution for dehumidification AND heating ✅ Combined heat output: 11.3 kW total (4.7 kW recovery + 8.9 kW LPHW) ✅ Motorized 3-way valve included for temperature control ✅ Reduces overall equipment cost and installation complexity

Requirements:

• Existing boiler system with capacity for additional 8.9 kW load
• 22mm copper connections for flow and return
• Boiler water temperature: 80°C (recommended for optimal performance)
• Wall-mounted air thermostat (included with heating models)
• LPHW flow rate: 9.6 litres/min

💡 Sizing Tip: Calculate your pool hall heat loss using Building Regulation U-values. If total heat requirement exceeds 11 kW, consider supplementary heating or the larger Monitair 110 model.

🔇 Noise Considerations

At 48.5 dB(A) measured at 3 meters, the Monitair 75 operates at a noise level comparable to:

• Quiet conversation
• Background music at low volume
• Modern refrigerator

This makes it suitable for environments where acoustics matter, including residential pools, therapy centers, and hotel spas. The noise profile is a low-frequency hum from the compressor and fan, easily masked by ambient pool activity.

Noise Reduction Tips:

• Through-wall installation naturally reduces pool hall noise
• Ensure unit is mounted on a structurally sound wall (vibration isolation)
• Regular filter maintenance prevents increased fan noise

🌊 Maintenance & Operational Notes

Routine Maintenance Schedule

Weekly:

• Visual inspection of condensate drainage (ensure free-flowing)

Monthly:

• Clean washable inlet and outlet air filters (access via grilles)
• Check humidistat setting (adjust if environmental conditions changed)

Quarterly:

• Inspect condensate drain trap for blockages
• Check electrical connections for corrosion

Annually:

• Professional service including refrigerant pressure check
• Coil cleaning (evaporator and condenser)
• Verify defrost cycle operation

Defrost System Operation

The standard defrost system automatically activates when evaporator coil temperature drops below freezing point. This allows reliable operation down to 5°C ambient temperature—essential for:

• Pools used seasonally with reduced winter heating
• Pools in unheated conservatory-style enclosures
• Energy-saving scenarios where space temperature is allowed to drop overnight

During defrost cycles, the compressor temporarily stops while the fan continues, using recovered heat to melt ice buildup. Cycles are brief and automatic—no user intervention required.

❓ Frequently Asked Questions

Q: What size pool hall can the Monitair 75 effectively dehumidify?

A: The DH75AX is designed for pool halls up to approximately 450 m³ in volume under typical conditions. For a standard 10m x 5m pool with 4m ceiling height (200 m³), this unit provides excellent capacity with headroom for peak demand periods. Larger installations may require the Monitair 110 or multiple units.

Q: Can I install the Monitair 75 myself, or do I need a professional?

A: Due to the unit’s weight (153 kg), electrical requirements (230V hardwired), refrigerant handling regulations, and critical installation parameters (especially for through-wall models), professional installation is strongly recommended. Incorrect installation can void warranty and result in poor performance. Seek a qualified pool engineer or HVAC specialist familiar with pool hall dehumidifiers.

Q: How much does it cost to run the Monitair 75?

A: At 1.46 kW power consumption, the unit costs approximately £0.44 per hour to run (based on £0.30/kWh electricity rate). For a typical pool operating 8-10 hours daily, expect £3.50-4.40 daily or £105-132 monthly in direct running costs. However, the energy recovery feature (4.7 kW heat output) significantly reduces your boiler/heating costs, often resulting in net savings of 50-70% compared to ventilation-only humidity control systems.

Q: What’s the difference between wall mount and through-wall models?

A: Wall mount (DH75AX): Entire unit is mounted on the pool hall wall, with air intake and discharge directly into the space. Simpler installation but equipment is visible.

Through-wall (DH75AX/T): Unit is located in an adjacent plant room, with only decorative grilles visible in the pool hall. Requires wall penetrations but offers cleaner aesthetics, quieter pool hall operation, and easier maintenance access. Supplied with grille kit.

Both versions offer identical dehumidification performance—choice depends on your facility layout and aesthetic preferences.

Q: Do I need the LPHW air heating option?

A: This depends on your pool hall’s total heat requirement. The standard DH75AX provides 4.7 kW of “free” heat from energy recovery, which may be sufficient for well-insulated, smaller pool halls or those with existing supplementary heating (radiators, underfloor heating).

Add LPHW heating (DH75AX/L) if:

• You want to eliminate separate fan heaters or radiators
• Your pool hall has moderate to high heat loss
• You have an existing boiler with spare capacity

The combined 11.3 kW output (4.7 + 8.9 kW) can heat most domestic pool halls without additional equipment.

Q: How long does the warranty last, and what does it cover?

A: The Monitair 75 includes a full 2-year manufacturer’s warranty covering parts and labour. This is backed by a nationwide network of Certikin-trained service engineers. Register your unit after installation to activate coverage. Routine maintenance items (filters) and damage from incorrect installation or neglect are not covered.

Q: Can the Monitair 75 operate in very cold conditions?

A: Yes, the standard defrost system allows operation down to 5°C ambient temperature. This is sufficient for most UK pool installations, including conservatory-style enclosures and seasonal-use pools. The defrost cycle automatically prevents ice buildup on the evaporator coil, maintaining performance even in cooler conditions.

Q: How noisy is the unit during operation?

A: At 48.5 dB(A) measured at 3 meters, the Monitair 75 operates at a similar volume to a quiet conversation or modern refrigerator. Most users find the low-frequency hum unobtrusive, especially during active pool use. Through-wall installation further reduces pool hall noise by containing equipment in the plant room.

Q: What humidity level should I set the humidistat to?

A: For optimal indoor pool conditions, set the humidistat to maintain 50-60% relative humidity. This range:

• Minimizes condensation on windows and cold surfaces
• Prevents mold and bacteria growth
• Protects building structure from moisture damage
• Maintains comfortable swimming environment
• Reduces chloramine concentration

Adjust within the 20-80% range based on seasonal conditions and personal preference, but avoid settings below 45% (uncomfortably dry) or above 65% (condensation risk).

Q: Do I need to empty a water tank, or is drainage automatic?

A: The Monitair 75 features automatic condensate drainage via a 15mm stub connection. Condensate is plumbed to a nearby drain (gravity drainage preferred) or connected to a condensate pump if required to lift to drain level. There is no water tank to empty—the system operates fully automatically once commissioned.

Q: Can I control the unit remotely or integrate it with building management systems?

A: The standard DH75AX includes an adjustable humidistat for automatic operation based on humidity level. For LPHW heating models (DH75AX/L), a wall-mounted air thermostat is included for temperature control. Remote control and BMS integration are not standard features but may be achievable through third-party controls—consult with your installer for options.

Q: What maintenance is required, and how often?

A: Monthly: Clean washable air filters (5-minute task) Quarterly: Check condensate drainage and electrical connections Annually: Professional service including coil cleaning, refrigerant check, and defrost system verification

Regular filter maintenance is critical—blocked filters reduce efficiency and increase energy consumption. The unit is designed for long-term reliability with minimal intervention when properly maintained.

📥 Downloads & Technical Documentation

Access comprehensive product information, installation guides, and pool hall design resources:

📄 Monitair 110 Specifications & Installation Guide (opens in new tab) Complete technical specifications for the Monitair range, including detailed dimensional drawings, electrical schematics, and through-wall installation details.

📄 Vaporex and Monitair Product Brochure 2022 (opens in new tab) Full-color brochure covering the complete Calorex Monitair dehumidifier range with performance data, model comparisons, and application guidance.

📄 Guidelines to Pool Hall Construction 2022 (opens in new tab) Essential reading for pool hall design: construction materials, insulation requirements, vapor barriers, condensation prevention, and humidity control strategies.

✅ Why Choose the Monitair 75 from Parts4Tubs?

Proven Performance – Part of the industry-leading Calorex range by Certikin, trusted in thousands of pool installations across the UK

Energy Efficiency – Heat recovery technology delivers up to 70% savings on space heating costs compared to traditional ventilation methods

Long-Term Reliability – Built specifically for the harsh, corrosive environment of indoor pool halls with robust construction and quality components

Comprehensive Support – 2-year warranty backed by nationwide service engineers and technical support

Flexible Installation – Wall mount or through-wall options with optional LPHW heating integration

Quiet Operation – Suitable for residential, therapeutic, and hospitality environments where acoustics matter

Environmental Responsibility – R407C ozone-friendly refrigerant and energy recovery technology reduce your carbon footprint

🛒 Technical Summary

The DH75AX Monitair 75 delivers professional-grade dehumidification for medium to large indoor pool environments. With 3.6 L/hr moisture removal capacity, 4.7 kW energy recovery, advanced defrost for year-round operation, and optional LPHW air heating, this single-phase unit provides a complete environmental control solution.

Whether you’re protecting a new pool investment, retrofitting an existing facility, or replacing aging equipment, the Monitair 75 offers the perfect balance of performance, efficiency, and value.

Transform your pool hall environment today. Experience superior humidity control, reduced energy costs, and long-term structural protection with the Monitair 75 dehumidifier.