💨 Dantherm DH35 Wall-Mounted Pool Dehumidifier with Defrost + 3.8kW LPHW Heating

Professional humidity control and air heating for indoor swimming pools, therapy pools, and spa facilities

The Dantherm DH35AX/L represents the perfect balance of powerful dehumidification and efficient air heating for small to medium-sized indoor pool environments. This wall-mounted unit combines advanced moisture removal technology with a factory-fitted 3.8kW Low Pressure Hot Water (LPHW) heating coil, eliminating the need for separate radiators or fan heaters in your pool room.

Designed specifically for the harsh, corrosive conditions found in indoor pool halls, this unit features a robust aluminium housing with fully anti-corrosion coated coils, ensuring years of reliable operation. The dual-position LPHW pipework connections provide exceptional installation flexibility, while the electronic humidistat maintains precise humidity control between 40% and 80% RH.

✅ Key Benefits at a Glance:

• Removes up to 30 litres of moisture per 24 hours
• Delivers 3.8kW of supplementary air heating via LPHW
• Total heat output of 5kW (2kW heat recovery + 3.8kW LPHW)
• Protects building structure from moisture damage and mould
• Reduces energy costs through efficient heat recovery technology
• Operates quietly at just 46 dB(A) at 3 metres
• Space-saving wall-mounted design (885mm W × 720mm H × 265mm D)

🎯 Perfect For

✓ Domestic Indoor Pools (up to 25m² surface area) Maintain comfortable, dry conditions in your home pool environment while preventing condensation on windows and structural damage to your property.

✓ Therapy & Hydrotherapy Pools Precise humidity control creates the ideal environment for therapeutic treatments, protecting sensitive equipment and ensuring patient comfort.

✓ Small Hotel & Spa Pools Professional-grade performance ensures guest comfort and protects your facility investment from moisture-related deterioration.

✓ Health Club & Gym Pools Reliable operation in commercial settings with easy-to-use controls that require minimal staff intervention.

🔬 Technical Specifications

Dehumidification Performance

Specification	Value	Unit
Dehumidification Capacity (Hourly)	1.22	L/hr
Dehumidification Capacity (Daily)	30	L/day
Heat Recovery Output	2.0	kW
LPHW Air Heating Output	3.8	kW
Total Heat Output	5.0	kW
Air Flow Rate	500	m³/hr
Operating Temperature Range	5°C to 35°C	°C
Humidity Control Range	40% to 80%	RH
Refrigerant Type	R454C	–

LPHW (Low Pressure Hot Water) System

Specification	Value	Unit
LPHW Flow Rate	5.0	L/min
LPHW Pressure Drop	3.5	m head
Required Water Supply Temperature	80	°C
LPHW Heating Output	3.8	kW
Motorised Valve Control	Yes (valve & transformer by others)	–
Air Stat Included	Yes (1x separate)	–

Electrical Specifications

Specification	Value	Unit
Power Supply	230V / 50Hz	–
Fuse Rating	10	Amp
Nominal Running Current	4.0	Amp
Full Load Amps (FLA)	4.6	Amp
Power Consumption	0.87	kW
Compressor LRA	12.2	Amp

Physical & Installation

Specification	Value	Unit
Width (unpacked)	885	mm
Height (unpacked)	720	mm
Depth (unpacked)	265	mm
Condensate Drain Connection	16	mm
Noise Level @ 3m	46	dB(A)
Housing Material	Aluminium	–
Coil Coating	Full anti-corrosion	–
Mounting Type	Wall-mounted	–
Weight	Approx. 45kg	kg

📄 Technical Documentation & Resources

Complete Product Information & Installation Guidance

All technical specifications, installation instructions, electrical requirements, and maintenance guidance are provided in the comprehensive manufacturer documentation below.

📄 Dantherm Non-Ducted Swimming Pool Dehumidifiers – Complete Technical Brochure (opens in new tab)

This detailed PDF document includes:

• Full technical specifications for the entire DH range (DH35, DH65, DH75, DH110, DH120)
• Detailed dimension drawings and mounting requirements
• LPHW pipework connection diagrams (dual-position options)
• Electrical connection requirements and wiring diagrams
• Performance data charts based on varying conditions
• Through-the-wall installation options for DH75/DH110 models
• Maintenance schedules and service recommendations
• Warranty information and support contacts
• Comparison tables for selecting the right model for your pool size

⚠️ Important Installation Notes: This document contains critical information about clearance requirements, condensate drainage, LPHW system integration, and electrical connections. Please review thoroughly before installation or consult with a qualified pool equipment installer.

🌟 Key Features & Benefits

💧 Powerful Moisture Control

Removes up to 30 litres of moisture per day, effectively controlling humidity levels to prevent condensation, mould growth, and structural damage in your pool room. The advanced heat recovery system converts moisture energy into useful heat, reducing overall running costs.

🔥 Integrated LPHW Air Heating

The factory-fitted 3.8kW Low Pressure Hot Water heating coil provides supplementary air heating without the need for separate radiators or fan heaters. This dual-function design saves space, reduces installation costs, and simplifies your pool room HVAC system.

🛡️ Corrosion-Resistant Construction

Purpose-built for the challenging pool environment with a robust aluminium housing and fully anti-corrosion coated coils. Unlike standard dehumidifiers, this unit is engineered to withstand continuous exposure to chlorinated air and high humidity.

🎛️ Precision Electronic Humidistat

Set your desired humidity level anywhere between 40% and 80% RH. The electronic humidistat automatically maintains optimal conditions, protecting your pool building while ensuring swimmer comfort.

🔄 Dual Position LPHW Connections

Flexible pipework connection options (top or side mounting) accommodate various installation scenarios and building layouts, making professional installation easier and more cost-effective.

❄️ Automatic Defrost Function

Standard defrost capability allows safe operation in pool rooms down to 5°C, essential for maintaining humidity control during colder months or in pools used year-round.

🔇 Whisper-Quiet Operation

Operating at just 46 dB(A) at 3 metres, this unit runs quietly in the background without disrupting the peaceful pool environment. Comparable to a quiet office or library.

⚡ Two Fan Operating Modes

Choose between Cycle Mode (intermittent operation for energy savings) or Continuous Mode (constant operation for maximum dehumidification) based on your pool usage patterns and humidity loads.

🌍 Environmentally Responsible Refrigerant

Uses R454C refrigerant, a modern low-GWP (Global Warming Potential) alternative that delivers excellent performance while reducing environmental impact.

💰 Energy-Efficient Heat Recovery

The air-to-air heat recovery system reclaims 2kW of heat from the dehumidification process, reducing the demand on your boiler and lowering energy bills. When combined with the 3.8kW LPHW heating, you get 5kW total heat output to the pool room.

📊 Real-World Performance Guide

Room Size Suitability

The DH35AX/L is ideally suited for indoor pool environments with the following characteristics:

Pool Surface Area	Pool Volume	Typical Applications	Coverage Rating
15-25 m²	25-45 m³	Small domestic pools, plunge pools	✅ Excellent
25-35 m²	45-60 m³	Medium domestic pools, therapy pools	✅ Good
35-50 m²	60-80 m³	Larger domestic pools	⚠️ Consider DH65
50+ m²	80+ m³	Commercial pools, multi-pool facilities	❌ Use DH65/DH75

💡 Sizing Tip: Pool surface area is more important than volume for dehumidifier sizing, as evaporation occurs at the water surface. Higher pool temperatures, more swimmers, and open doors/windows all increase moisture load.

Estimated Dehumidification Performance

Based on standard pool hall conditions (30°C air temperature, 60% RH, 28°C pool water):

Room Humidity Level	Time to Reduce RH by 10%	Moisture Removed	Application
High (70-80% RH)	4-6 hours	5-7 litres	After heavy pool use or humid weather
Moderate (60-70% RH)	6-8 hours	7-10 litres	Normal daily operation
Maintenance (50-60% RH)	Continuous	1.2 L/hr average	Maintaining target humidity

⚠️ Performance Variables:

• Pool water temperature (warmer = more evaporation)
• Air temperature and ventilation rates
• Number of swimmers and usage patterns
• Door/window opening frequency
• Building insulation quality
• Weather conditions (outdoor humidity)

Annual Running Cost Estimates

Based on UK average electricity rates (£0.24/kWh) and continuous operation:

Operating Mode	Daily Cost	Monthly Cost	Annual Cost	Notes
Cycle Mode (12 hrs/day avg)	£2.51	£75.30	£916.95	Typical domestic use
Continuous Mode (24 hrs/day)	£5.01	£150.60	£1,833.90	Commercial or heavy use
Seasonal Use (6 months)	–	–	£458.48	Spring/Summer operation only

💰 Cost Savings vs Alternatives:

• Without Heat Recovery: Running costs could be 40-60% higher
• Vs Gas Heating Only: The 2kW heat recovery reduces annual gas consumption by approximately 15,000 kWh, saving £600-£900/year
• LPHW Integration: Using existing boiler capacity is more efficient than electric-only heating

Note: Actual costs vary based on electricity tariffs, pool usage, ambient conditions, and thermostat settings.

Energy Efficiency & Payback

Metric	Value	Comparison
Heat Recovery Efficiency	230% (2kW heat from 0.87kW input)	Exceptional
Total System Efficiency	575% (5kW total output)	When including LPHW
Payback Period	3-5 years	Vs electric heating only
Equipment Lifespan	10-15 years	With proper maintenance

🔧 Installation Requirements & Guidelines

Minimum Clearances Required

⚠️ Critical for safe operation and maintenance access:

Location	Clearance	Reason
Top	300mm	Hot air discharge, service access
Sides	200mm each	Air circulation, panel removal
Bottom	100mm	Condensate drainage, air intake
Front	600mm	Control access, filter maintenance

Electrical Requirements

✅ Must be installed by qualified electrician:

• Dedicated 230V / 50Hz supply
• 10A motor-rated fuse or MCB
• RCD protection (30mA trip)
• IP44 rated connections minimum (pool environment)
• Cable routing away from moisture sources

LPHW System Integration

🔥 Professional plumbing required:

• 15mm or 22mm LPHW pipework (depending on flow rate)
• Water supply at 80°C for rated output
• System pressure: 1-3 bar typical
• Motorised 3-port valve (supplied by installer)
• Low voltage transformer for air stat (supplied by installer)
• Balancing valve for flow regulation
• Air separator/vent on return line

💡 LPHW Installation Tip: The dual-position pipework connections (top or side entry) provide flexibility for various installation scenarios. Consult the technical brochure for connection diagrams.

Condensate Drainage

💧 Essential for continuous operation:

• 16mm condensate drain connection
• Fall of minimum 1:40 towards drain point
• Trap depth minimum 50mm to prevent air ingress
• Discharge to appropriate drainage point
• Consider condensate pump if gravity drainage not possible

Mounting Considerations

🏗️ Structural requirements:

• Wall must support minimum 60kg (unit weight + safety factor)
• Solid wall construction preferred (masonry, concrete)
• Stud walls require additional bracing/support
• Anti-vibration mountings recommended for noise reduction
• Level installation critical for condensate drainage

❓ Frequently Asked Questions

General Operation

Q: How does the DH35 control humidity in my pool room?

A: The DH35 works by drawing in humid air from your pool room, passing it over a cold evaporator coil where moisture condenses and drips away. The now-dried air is then reheated (both by the heat recovery system and the LPHW coil) before being returned to the room. The electronic humidistat constantly monitors humidity levels and cycles the unit on/off to maintain your target RH setting between 40-80%.

Q: What’s the difference between heat recovery and LPHW heating?

A: Heat Recovery (2kW) is “free heat” reclaimed from the dehumidification process itself – the unit captures the latent heat energy contained in water vapour as it condenses. LPHW Heating (3.8kW) uses hot water from your boiler flowing through a heating coil to provide additional air heating. Together, they deliver 5kW total heat output to your pool room, often eliminating the need for separate radiators.

Q: Can I run this unit without connecting the LPHW heating?

A: Yes, the unit will operate perfectly well in dehumidification-only mode if you choose not to connect the LPHW system. However, you won’t benefit from the 3.8kW of supplementary heating, and you’ll still get the 2kW heat recovery output. Note that you’re paying for the LPHW coil whether you use it or not, so it’s economically wise to integrate it with your existing boiler system.

Sizing & Suitability

Q: How do I know if the DH35 is the right size for my pool?

A: The DH35 is ideal for pool surface areas of 15-35 m². Key factors to consider:

• Pool surface area (more important than volume)
• Pool temperature (warmer = more evaporation)
• Room ventilation (more air changes = more moisture load)
• Usage patterns (frequent swimmers = higher humidity)

If your pool is larger than 35 m², experiences heavy use, or has poor building insulation, consider upgrading to the DH65 model (50 L/day capacity).

Q: My pool room is 40 m². Will the DH35 work?

A: The DH35 would be undersized for a 40 m² pool, especially with regular use. You’d likely find it running continuously without adequately controlling humidity. We strongly recommend the Dantherm DH65AX/L (50 L/day capacity) for pools of this size. An undersized dehumidifier leads to poor humidity control, higher running costs, and reduced equipment lifespan.

Q: What happens if I have too small a dehumidifier for my pool?

A: An undersized unit will run continuously trying to meet demand, leading to:

• Higher electricity bills (constant operation)
• Inadequate humidity control (persistent condensation)
• Premature component wear and failure
• Uncomfortable environment for swimmers
• Accelerated building deterioration

Installation & Setup

Q: Can I install this myself or do I need a professional?

A: We strongly recommend professional installation for several reasons:

• Electrical work: Must comply with UK electrical regulations (Part P)
• LPHW integration: Requires competent plumbing and heating knowledge
• Refrigeration system: Pre-charged but must be handled carefully
• Warranty protection: Professional installation often required for warranty validity
• Safety: Pool environments have specific electrical safety requirements

However, the unit comes pre-charged with refrigerant and pre-wired, so the installation is straightforward for qualified tradespeople.

Q: What maintenance does the DH35 require?

A: Regular maintenance ensures optimal performance and longevity:

Monthly:

• Check and clean air filter (remove, vacuum, or wash with warm water)
• Inspect condensate drainage for blockages
• Verify humidity levels are being maintained

Quarterly:

• Deep clean coils using approved coil cleaner
• Check all electrical connections are tight
• Inspect condensate drain trap

Annually:

• Professional service including refrigerant pressure check
• Full electrical safety inspection
• LPHW system check (valves, pipework, connections)
• Replace any worn components

Q: Where should the DH35 be mounted for best performance?

A: Optimal placement guidelines:

• Height: 1.5-2m above floor level (away from splashing)
• Location: Away from direct water spray or splash zones
• Air circulation: Unobstructed air intake and discharge
• Service access: Easy access to controls and filter
• Condensate drainage: Gravity drain to suitable discharge point
• Avoid: Direct sunlight, heat sources, narrow alcoves

Operation & Performance

Q: How long will it take to dry out my pool room initially?

A: Initial drying after commissioning or a period of high humidity depends on several factors:

Starting RH	Target RH	Pool Size	Estimated Time
80% → 60%	60%	25 m² pool	48-72 hours
70% → 60%	60%	25 m² pool	24-36 hours
60% → 50%	50%	25 m² pool	12-24 hours

Note: These are estimates assuming closed doors/windows, stable temperature, and no pool use during the initial dry-down period.

Q: Why is there still condensation on my windows despite the dehumidifier running?

A: Window condensation can occur even with good dehumidification if:

• Cold spots: Single-glazed or poorly insulated windows create cold surfaces below the dew point
• Inadequate air circulation: Dead air pockets around windows
• Oversaturation: Dehumidifier undersized or not running enough
• Air temperature: Room temperature too low (increase LPHW output)

Solutions: Improve window insulation, increase air circulation with ceiling fans, ensure unit is sized correctly, and maintain room temperature at 28-30°C.

Q: What humidity level should I set for my pool room?

A: Recommended settings:

Season	Target RH	Room Temp	Reason
Summer	50-60%	28-30°C	Comfortable, prevents excess evaporation
Winter	55-65%	28-30°C	Prevents static, maintains comfort
Pool in use	55-60%	28-30°C	Optimal swimmer comfort
Pool not in use	50-55%	26-28°C	Energy savings, building protection

⚠️ Warning: Do not set below 40% RH (static electricity, dry skin) or above 70% RH (mould growth risk, structural damage).

Energy & Running Costs

Q: How much does it cost to run the DH35 per day?

A: Based on UK average electricity rates (£0.24/kWh):

Cycle Mode (typical domestic use, ~12 hours operation):

• Power consumption: 0.87kW × 12 hours = 10.44 kWh
• Daily cost: 10.44 × £0.24 = £2.51/day

Continuous Mode (heavy use, 24 hours operation):

• Power consumption: 0.87kW × 24 hours = 20.88 kWh
• Daily cost: 20.88 × £0.24 = £5.01/day

Reality: Most domestic pools will operate in cycle mode, with actual runtime varying by conditions. Expect £75-100/month in typical use.

Q: Will this save me money compared to just ventilating?

A: Absolutely yes. Here’s why:

Dehumidifier with Heat Recovery:

• Reclaims 2kW heat from moisture
• Reduces boiler demand
• Maintains room temperature
• Annual energy cost: £900-1,800

Ventilation Only:

• Exhausts warm humid air (heat loss)
• Requires heating cold incoming air
• Much higher boiler demand
• Annual energy cost: £2,500-4,000+

Savings: £1,000-2,000+ per year with heat recovery dehumidification.

Technical & Troubleshooting

Q: What is R454C refrigerant and why does it matter?

A: R454C is a modern, environmentally responsible refrigerant with:

• Low GWP: Much lower Global Warming Potential than older refrigerants (R134a, R22)
• Energy efficient: Excellent thermodynamic properties for heat pump applications
• Non-flammable: A2L safety classification (mildly flammable under extreme conditions)
• Future-proof: Compliant with current and forthcoming refrigerant regulations

For you as a pool owner, this means reliable long-term operation without concerns about refrigerant phase-outs or regulatory issues.

Q: The unit is running but not removing moisture. What’s wrong?

A: Several possibilities:

1. Humidistat setting too low:

• Check current RH vs target setting
• Increase target RH temporarily to see if unit runs

2. Defrost cycle active:

• Unit periodically defrosts evaporator coil
• Normal operation, wait 10-15 minutes

3. Low ambient temperature:

• Unit operates down to 5°C but with reduced capacity
• Ensure room temperature is 25°C+

4. Dirty air filter or coils:

• Restricted airflow reduces performance dramatically
• Clean or replace filter, clean coils

5. Refrigerant leak:

• Requires professional service
• Contact qualified refrigeration engineer

Q: Can the DH35 operate in cold weather / winter months?

A: Yes, the DH35 is equipped with an automatic defrost function that allows safe operation down to 5°C ambient temperature. However, dehumidification capacity reduces as temperature decreases:

Temperature	Capacity	Notes
30°C	100% (30 L/day)	Rated performance
20°C	~70% (21 L/day)	Reduced but adequate
10°C	~40% (12 L/day)	Minimum practical operation
5°C	~20% (6 L/day)	Defrost cycles frequent

For year-round pool operation, maintain room temperature above 25°C using the LPHW heating system for optimal dehumidification performance.

🛒 What’s Included

In the Box:

• ✅ Dantherm DH35AX/L wall-mounted dehumidifier unit
• ✅ Factory-fitted 3.8kW LPHW heating coil
• ✅ Dual-position LPHW pipework connections
• ✅ Electronic humidistat control panel
• ✅ Separate air stat for LPHW system control
• ✅ Wall mounting brackets and hardware
• ✅ 16mm condensate drain connection
• ✅ Comprehensive installation and operation manual

Required for Installation (Not Included):

• ❌ Motorised 3-port valve for LPHW control
• ❌ Low voltage transformer for air stat
• ❌ Electrical cabling and consumer unit connection
• ❌ LPHW pipework, fittings, and system integration
• ❌ Condensate drainage pipework
• ❌ Professional installation labour

⚙️ Technical Notes & Disclaimers

Performance Data Standards: All dehumidification and heating performance figures are based on standardized test conditions:

• Air temperature: 30°C
• Relative humidity: 60% RH
• Pool water temperature: 28°C
• LPHW supply temperature: 80°C (for heating output)

Real-World Performance: Actual performance will vary based on:

• Ambient temperature and humidity levels
• Pool water temperature and surface area
• Room ventilation and air circulation
• Usage patterns and swimmer load
• Building insulation and construction
• Door/window opening frequency
• Outdoor weather conditions

LPHW System Requirements:

• Requires competent integration with existing heating system
• Motorised valve and transformer must be specified and supplied by installer
• LPHW output stated requires 80°C water supply temperature
• Lower supply temperatures will result in proportionally reduced heating output
• System balancing essential for optimal performance

Electrical Safety:

• Installation must comply with current UK electrical regulations (18th Edition BS 7671)
• Pool environment requires enhanced electrical safety measures
• RCD protection mandatory (30mA trip rating)
• IP44 minimum rating for connections in pool areas
• Professional installation by qualified electrician required

Warranty:

• 2-year manufacturer’s warranty (terms and conditions apply)
• Warranty validity typically requires professional installation
• Regular maintenance required to maintain warranty coverage
• Nationwide network of service engineers available

Environmental Conditions:

• Designed for indoor use only
• Operating temperature range: 5°C to 35°C
• Maximum humidity: 90% RH
• Not suitable for outdoor or exposed locations
• Corrosion-resistant design for chlorinated environments

🌍 Why Choose the Dantherm DH35?

Proven Technology from Industry Leaders Dantherm is a global leader in climate control solutions for swimming pools, combining decades of engineering expertise with cutting-edge technology. The DH35 represents the evolution of proven pool dehumidification design, incorporating customer feedback and the latest efficiency improvements.

Purpose-Built for Pool Environments Unlike domestic dehumidifiers adapted for pool use, the DH35 is engineered from the ground up for the harsh conditions of indoor pool halls. Every component—from the corrosion-resistant coils to the aluminium housing—is specified to withstand continuous exposure to chlorinated air and high humidity.

Total System Integration The integrated LPHW heating eliminates the need for separate air heating equipment, simplifying your pool room HVAC system and reducing installation costs. The dual-function design means one piece of equipment handles both humidity control and supplementary heating.

Long-Term Value With proper maintenance, the DH35 will provide 10-15 years of reliable service, protecting your pool building from moisture damage worth thousands of pounds in potential repairs. The energy-efficient heat recovery pays for itself multiple times over the unit’s lifespan.

Professional Support Network Backed by Certikin International’s nationwide service network, you have access to qualified engineers for installation, commissioning, maintenance, and repairs throughout the UK.

📞 Need Help Choosing?

Not sure if the DH35 is right for your pool?

Our technical team can help you determine the correct dehumidifier size based on:

• Pool surface area and volume
• Room dimensions and construction
• Usage patterns and swimmer load
• Existing heating and ventilation systems
• Budget and installation constraints

🚚 Delivery & Installation

Free UK Mainland Delivery This product qualifies for free delivery to most UK mainland addresses. Typical delivery time is 3-5 working days from order confirmation.

Installation Service Available Professional installation can be arranged through our network of approved pool engineers. Contact us for a quotation including:

• Full electrical connection and testing
• LPHW system integration with existing boiler
• Condensate drainage installation
• Commissioning and handover
• System operation training

Self-Installation If you choose to install the unit yourself using qualified tradespeople, we provide full technical support and guidance throughout the installation process.

🛡️ Warranty & Support

2-Year Manufacturer’s Warranty Comprehensive coverage for parts and labour, subject to terms and conditions. Professional installation and regular maintenance typically required to maintain warranty validity.

Nationwide Service Network Access to qualified service engineers throughout the UK for installation, commissioning, maintenance, and repairs.

Technical Support Expert technical advice available by phone or email to help with sizing, installation planning, troubleshooting, and optimization.

Spare Parts Availability Full range of genuine Dantherm spare parts available for long-term serviceability and reliability.

🔐 Quality Certifications

• ✅ ISO 9001 Registered Quality Management
• ✅ CE Certified
• ✅ UK Building Regulations Compliant
• ✅ F-Gas Regulations Compliant
• ✅ Manufactured to European Safety Standards