Dantherm DH35 Dehumidifier with Defrost – 30L/Day Wall-Mounted Pool Dehumidifier with Optional LPHW or Electric Heating 🌊

Protect your swimming pool building from moisture damage while creating a warm, dry, and comfortable environment. The Dantherm DH35 is a powerful wall-mounted condensation dehumidifier specifically engineered for indoor swimming pools, therapy pools, health clubs, and spa facilities. With the ability to extract up to 30 litres of moisture per day, this compact yet highly efficient unit prevents mould, mildew, corrosion, and structural damage caused by excess humidity.

The DH35 stands out as the intelligent replacement for the Vaporex range, offering larger LPHW air heating capacity in a comparable physical size with minimal adjustments needed to existing pipework connections. Available in three configurations – standard heat recovery only, with factory-fitted LPHW heating coil, or with electric heating element – the DH35 adapts to your specific pool room heating requirements.

The Dantherm DH35 doesn’t just remove moisture – it recovers the latent energy locked in that moisture and converts it into useful heat for your pool room. This “free heat” is environmentally friendly, accelerates the drying process, keeps your boiler off for longer periods, reduces evaporation from the pool surface, and creates a consistently warm and dry environment.

Key Benefits:

✅ Superior Moisture Control – Removes 30 litres per day (1.22L/hour), effectively managing humidity in small to medium-sized pool rooms

✅ Energy-Efficient Heat Recovery – Recovers 2kW of heat from dehumidification alone, reducing your heating costs significantly

✅ Flexible Heating Options – Choose LPHW heating (3.8kW additional heat) or electric heating (2kW) to eliminate separate fan heaters or radiators

✅ Total Heat Output – Up to 5kW total heat when combining heat recovery with LPHW, or 4kW with electric heating

✅ Built for Pool Environments – Aluminium housing with fully anti-corrosion coated coils ensures long-lasting performance in humid, chlorine-rich atmospheres

✅ Precise Humidity Control – Electronic humidistat adjustable from 40% to 80% RH lets you dial in your ideal comfort level

✅ Operates in Cold Conditions – Standard defrost function allows operation down to 5°C, perfect for year-round use

✅ Quiet Operation – Just 46dB(A) at 3 meters – quieter than normal conversation

✅ Dual Fan Modes – Choose between Cycle mode for routine maintenance or Continuous mode for maximum moisture removal

✅ Compact Wall-Mount Design – Space-saving installation measuring just 885mm wide × 720mm high × 265mm deep

📋 Technical Specifications

Dehumidification Performance

Specification	DH35AX (Standard)	DH35AX/L (LPHW Heating)	DH35AX/E (Electric Heating)
Dehumidification Capacity	30 litres/day (1.22 L/hr)	30 litres/day (1.22 L/hr)	30 litres/day (1.22 L/hr)
Heat Recovery Output	2.0 kW	2.0 kW	2.0 kW
LPHW Air Heating	Not available	3.8 kW	Not available
Electric Heat Output	Not available	Not available	2.0 kW
Total Heat Output	2.0 kW	5.0 kW (combined)	4.0 kW (combined)
Airflow Rate	500 m³/hr	500 m³/hr	500 m³/hr

Performance figures based on air at 30°C and 60% RH, pool water at 28°C, with boiler water at 80°C for LPHW models

LPHW Heating Specifications (DH35AX/L Model)

Specification	Value
LPHW Flow Rate	5 litres/min
LPHW Pressure Drop	3.5 m head
Dual Position Pipework Connections	Yes – flexible installation

Electrical Specifications

Specification	DH35AX (Standard)	DH35AX/L (LPHW)	DH35AX/E (Electric)
Electrical Supply	230V / 50Hz	230V / 50Hz	230V / 50Hz
Fuse Rating	10 Amp	10 Amp	20 Amp
Nominal Running Current	4.0 Amp	4.0 Amp	12.7 Amp
Full Load Amps (FLA)	4.6 Amp	4.6 Amp	13.3 Amp
Power Consumption	0.87 kW	0.87 kW	2.87 kW
Compressor LRA	12.2 Amp	12.2 Amp	12.2 Amp

Fuses should be motor-rated

Physical Dimensions & Installation

Specification	Measurement
Width	885 mm
Height	720 mm
Depth	265 mm
Mounting Type	Wall-mounted
Condensate Drain	16 mm connection
Noise Level @ 3m	46 dB(A)

Construction & Reliability

Feature	Specification
Housing Material	Aluminium with corrosion-resistant coating
Coil Coating	Fully anti-corrosion coated evaporator and condenser coils
Refrigerant	R454C (low GWP eco-friendly refrigerant)
Defrost System	Standard – operates down to 5°C
Humidistat	Electronic, adjustable 40% to 80% RH
Fan Modes	2 modes – Cycle and Continuous
Warranty	2 years manufacturer’s warranty

📄 Downloads & Documentation

Access comprehensive technical information and installation guides:

📄 Dantherm Non-Ducted Swimming Pool Dehumidifiers Complete Brochure (opens in new tab) This detailed PDF document contains full technical specifications for the entire Dantherm dehumidifier range (DH35, DH65, DH75, DH110, DH120), installation diagrams for wall-mount and through-the-wall models, performance data tables, dimensional drawings with pipework connection positions, electrical wiring requirements, and operational guidelines. Essential reading for installers and specifiers.

🏊 Room Size & Application Guide

Suitable Pool Room Volumes

The Dantherm DH35 is ideally suited for small to medium-sized indoor pool installations:

Pool Type	Typical Pool Size	Pool Room Volume	DH35 Suitability
Domestic Pools	3m × 7m (21m²)	Up to 150 m³	✅ Excellent
Small Therapy Pools	3m × 5m (15m²)	Up to 120 m³	✅ Excellent
Exercise Pools	2.5m × 5m (12.5m²)	Up to 100 m³	✅ Excellent
Spa Pool Rooms	2m × 3m hot tub area	Up to 80 m³	✅ Excellent

💡 For larger pool rooms (150+ m³), consider the Dantherm DH65 model which removes 50 litres per day, or contact us for a professional assessment.

Performance in Different Conditions

Pool Room Temperature	Relative Humidity	Expected Moisture Extraction
28-30°C	60-70% RH	25-30 litres/day
26-28°C	50-60% RH	20-25 litres/day
24-26°C	40-50% RH	15-20 litres/day

⚠️ These are estimates based on typical operating conditions. Actual performance depends on pool water temperature, air temperature, humidity levels, pool surface area, bather load, and room ventilation.

💰 Running Cost Comparison

Annual Energy Consumption Estimates

Assuming 8 hours operation per day, 365 days per year:

Model	Power Consumption	Daily Usage	Annual kWh	Annual Cost*
DH35AX (Standard)	0.87 kW	6.96 kWh	2,540 kWh	£762
DH35AX/L (LPHW)	0.87 kW	6.96 kWh	2,540 kWh	£762
DH35AX/E (Electric)	2.87 kW	22.96 kWh	8,380 kWh	£2,514

Based on UK average electricity rate of £0.30/kWh (November 2025). LPHW models require boiler operation for heating function – costs will vary based on boiler fuel type.

Heating Cost Savings

The DH35 recovers 2kW of “free heat” from the dehumidification process. Over a year, this equates to:

• 5,840 kWh of recovered heat energy annually (8 hrs/day operation)
• £1,752 worth of heating saved per year
• Net running cost: As low as -£990/year (you save more than it costs to run!)

🌱 This recovered heat is completely free and environmentally friendly, significantly reducing your pool’s carbon footprint while lowering energy bills.

🔧 Installation & Mounting Requirements

Wall Mounting Specifications

✅ Mounting Height: Typically installed 2-3 meters above floor level for optimal air circulation

✅ Wall Load-Bearing: Minimum 50kg load capacity required for secure mounting

✅ Clearances Required:

• Minimum 300mm clearance on sides for air circulation
• Minimum 500mm clearance below unit for service access
• Minimum 200mm clearance above for air intake

✅ Drainage: 16mm condensate drain connection required – can be plumbed to waste or pool water return

✅ Electrical: Dedicated circuit with appropriate motor-rated fuse (10A for standard/LPHW, 20A for electric heating)

LPHW Connection Details (DH35AX/L)

The DH35AX/L features dual position LPHW pipework connections for flexible installation:

• Connection Size: Standard 1/2″ BSP female connections
• Flow Rate Required: 5 litres/min
• Boiler Temperature: Designed for 80°C supply (55-85°C operating range)
• Pressure Drop: 3.5m head
• Motorized Valve: Built-in 3-way valve included
• Air Thermostat: Separate air stat supplied (connects to external motorized valve)

💡 The dual position connections mean minimal adjustments needed when replacing older Vaporex units – makes retrofits quick and cost-effective.

🎯 Operational Features & Control

Electronic Humidistat Control

The DH35 features an easy-to-use electronic humidistat that provides precise humidity control:

• Adjustable Range: 40% to 80% RH in 5% increments
• Recommended Settings:
  • Indoor Pools: 50-60% RH (optimal comfort and minimal condensation)
  • Therapy Pools: 55-65% RH (warmer, more humid environment)
  • Spa Areas: 45-55% RH (drier environment to prevent mould)

Two-Speed Fan Operation

🔄 Cycle Mode (Standard Operation)

• Dehumidifier operates in response to humidity sensor
• Fan cycles on/off to maintain setpoint
• Most energy-efficient for routine conditions
• Recommended for normal daily use

⚡ Continuous Mode (Boost Operation)

• Dehumidifier runs continuously
• Maximum moisture extraction rate
• Use when pool is heavily used or during humid weather
• Ideal for party events or high bather loads

Automatic Defrost Function

❄️ The DH35 includes standard defrost capability allowing operation down to 5°C ambient temperature. The intelligent defrost system:

• Monitors evaporator coil temperature
• Automatically reverses refrigeration cycle when ice detected
• Prevents frost buildup that reduces efficiency
• Enables year-round operation including winter months

⏱️ Humidity Reduction Timeline

How Quickly Does It Work?

The time required to reduce humidity depends on room volume, starting humidity, and temperature:

Pool Room Volume	Starting RH	Target RH	Estimated Time*
80 m³	75% → 55%	20% reduction	3-4 hours
100 m³	70% → 55%	15% reduction	4-5 hours
120 m³	75% → 55%	20% reduction	5-7 hours
150 m³	70% → 55%	15% reduction	7-9 hours

⚠️ These are estimates for initial humidity reduction with the unit running in Continuous mode. Ongoing maintenance in Cycle mode will keep humidity stable. Actual times vary with pool water temperature, air temperature, ventilation, and pool use.

Daily Moisture Management

A typical domestic indoor pool generates approximately:

• 15-25 litres of moisture per day (with pool cover when not in use)
• 25-40 litres of moisture per day (without pool cover, moderate use)
• 40-60 litres of moisture per day (heavy use, multiple swimmers)

The DH35’s 30 litre/day capacity handles most domestic and small commercial installations effectively, especially when combined with:

✅ A pool cover when not in use ✅ Reasonable ventilation (without excessive heat loss) ✅ Proper pool room temperature control (28-30°C)

🔇 Noise Levels & Acoustic Performance

At just 46 dB(A) at 3 meters, the DH35 is one of the quietest pool dehumidifiers available:

Noise Comparison	dB(A) Level
Whisper	30 dB
Quiet Library	40 dB
Dantherm DH35	46 dB ✅
Normal Conversation	60 dB
Vacuum Cleaner	70 dB

🔇 The DH35’s low noise output makes it perfect for residential installations, therapy pools, and health club environments where a quiet atmosphere is essential.

🌡️ Complete Heating Solutions

Option 1: DH35AX – Heat Recovery Only

Best for: Pool rooms with existing adequate heating systems

• Recovers 2kW of free heat from dehumidification
• Most energy-efficient option
• Lowest running costs
• Works alongside existing radiators or underfloor heating

💡 Choose this option if your pool room already has sufficient heating and you simply need reliable humidity control with bonus free heat recovery.

Option 2: DH35AX/L – With LPHW Heating

Best for: New installations or replacing combined heating/dehumidification systems

• Total heat output: 5kW (2kW heat recovery + 3.8kW LPHW)
• Eliminates need for separate fan heaters or radiators
• Integrates with existing central heating boiler
• Dual position pipework connections for easy installation
• Built-in motorized 3-way valve included
• Separate air thermostat for precise temperature control

💡 Choose this option to simplify your pool room services into one unit – dehumidification AND heating from a single wall-mounted appliance. Minimal pipework adjustments when replacing Vaporex units.

Option 3: DH35AX/E – With Electric Heating

Best for: Pool rooms without boiler access or retrofit applications

• Total heat output: 4kW (2kW heat recovery + 2kW electric)
• No pipework connections required – electrical only
• Factory-fitted pre-wired electric heating element
• Easily accessible built-in thermostat
• Simple installation with standard 230V supply

💡 Choose this option for the simplest installation where boiler connections aren’t practical or available. Ideal for standalone pool buildings or conversion projects.

❓ Frequently Asked Questions

1. What size pool room is the DH35 suitable for?

The DH35 is ideally suited for small to medium-sized domestic pool rooms up to approximately 150 m³ volume. This typically covers pools of 3m × 7m with standard ceiling heights. For larger installations or commercial settings, consider the DH65 (50L/day) or DH120 (94L/day) models from the same Dantherm range.

2. Can I use the DH35 for a hot tub room or spa?

Absolutely! The DH35 is perfect for hot tub rooms and spa environments. In fact, hot tubs generate significant moisture due to the higher water temperature, making a dehumidifier essential. The corrosion-resistant coating protects against chemicals used in spa water treatment.

3. How does heat recovery work, and how much energy does it save?

The DH35 works like a reverse refrigerator. As it condenses moisture from the air, it releases the latent heat energy that was locked in the water vapor. This “free heat” (2kW) is delivered back into your pool room, effectively heating the space while dehumidifying. Over a year, this can save £1,750+ in heating costs compared to using separate heating systems.

4. What’s the difference between LPHW and electric heating options?

LPHW (Low Pressure Hot Water): Connects to your existing central heating boiler, provides 3.8kW of additional heating, more cost-effective to run long-term, requires pipework installation.

Electric Heating: Uses standard 230V electricity, provides 2kW of additional heating, simpler installation (no pipework), higher running costs but ideal where boiler access isn’t available.

Both options deliver the same 2kW of heat recovery from dehumidification.

5. Do I need a pool cover if I have a dehumidifier?

While the DH35 will manage moisture effectively without a cover, using a pool cover when the pool isn’t in use dramatically reduces evaporation – potentially by 60-90%. This means:

• Lower running costs (dehumidifier works less)
• More stable humidity control
• Reduced heat loss from pool water
• Extended equipment lifespan

We strongly recommend using a pool cover in combination with the DH35 for optimal efficiency.

6. Can the DH35 operate in winter when the pool room gets cold?

Yes! The DH35 includes a standard defrost function that allows operation down to 5°C ambient temperature. The automatic defrost cycle prevents ice buildup on the coils, ensuring year-round reliable operation even in unheated or minimally heated pool rooms during winter.

7. How often does the unit need maintenance?

The DH35 requires minimal maintenance:

• Monthly: Clean/check air filters (washable)
• Quarterly: Visual inspection for corrosion or damage
• Annually: Professional service check (recommended)
• As needed: Check condensate drain for blockages

With proper care, Dantherm dehumidifiers are renowned for 10-15+ years of reliable service. All models come with a 2-year manufacturer’s warranty and are supported by a nationwide network of service engineers.

8. How loud is the DH35? Will it disturb pool users?

At just 46 dB(A) at 3 meters, the DH35 is quieter than normal conversation (60 dB). Most users find it creates a gentle background hum that’s barely noticeable during pool use. It’s significantly quieter than most fan heaters or older dehumidifier models.

9. Can I install this myself or do I need a professional?

While technically-minded individuals could install the standard DH35AX model, we strongly recommend professional installation for several reasons:

• Electrical work must comply with Part P Building Regulations
• LPHW models require qualified plumbing work
• Refrigerant systems should only be handled by F-Gas certified engineers
• Incorrect installation voids warranty
• Professional installation ensures optimal performance and safety

10. What refrigerant does the DH35 use? Is it environmentally friendly?

The DH35 uses R454C refrigerant, which has a very low Global Warming Potential (GWP) compared to older refrigerants. This makes it an environmentally responsible choice that complies with current and foreseeable future regulations. R454C is also non-toxic and non-flammable.

11. How does the humidistat work? What humidity level should I set?

The electronic humidistat continuously monitors air humidity and cycles the dehumidifier to maintain your set point. Recommended settings:

• Indoor swimming pools: 50-60% RH (prevents condensation, comfortable for swimmers)
• Therapy pools: 55-65% RH (warmer feeling, good for therapeutic use)
• Spa/hot tub rooms: 45-55% RH (prevents mould, less humid feeling)

The humidistat is adjustable from 40-80% RH in 5% increments, giving you complete control over your environment.

12. What happens to the condensate water? Where does it drain?

The DH35 condenses moisture into water which drains via a 16mm connection. You have two options:

1. Drain to waste: Plumb the condensate drain into your main drainage system
2. Return to pool: Some installations return the condensate to the pool to replace evaporated water (this is clean, distilled water)

The unit produces approximately 30 litres of condensate daily at full capacity, so a reliable drainage solution is essential.

✅ What’s Included

When you purchase the Dantherm DH35, you receive:

✅ Dantherm DH35 dehumidifier unit (model as selected) ✅ Wall mounting bracket kit ✅ Factory-fitted LPHW heating coil (L models) or electric heating element (E models) ✅ Separate air thermostat (LPHW models) ✅ Built-in motorized 3-way valve (LPHW models) ✅ Installation and operating manual ✅ 2-year manufacturer’s warranty ✅ Access to nationwide service engineer network

❌ Not included: Electrical wiring, LPHW pipework connections, condensate drain plumbing, external motorized valve (LPHW models), transformer (LPHW models) – these are supplied by installer.

🏆 Why Choose Parts4Tubs?

When you buy your Dantherm DH35 from Parts4Tubs, you benefit from:

🎯 Expert Advice – Our team understands pool and spa equipment inside-out

📦 Fast Dispatch – Quick delivery to get your pool room protected sooner

💰 Competitive Pricing – Excellent value on premium Dantherm equipment

🔧 Technical Support – Help with product selection and installation guidance

📄 Comprehensive Documentation – Full specs and installation manuals provided

🌟 Quality Guaranteed – All Dantherm products come with manufacturer’s warranty

📞 Need Help Choosing?

Selecting the right dehumidifier configuration for your pool room is important. If you’re unsure whether the DH35 is the right model, or whether you need LPHW or electric heating, our team is here to help.

Get in touch and we can advise on:

✓ Correct dehumidifier sizing for your pool room volume ✓ LPHW vs. electric heating – which is best for your installation ✓ Installation requirements and considerations ✓ Running cost calculations for your specific situation ✓ Comparison with other Dantherm models (DH65, DH75, DH110, DH120)

🌊 Technical Summary

The Dantherm DH35 represents the perfect balance of compact size, effective moisture control, and integrated heating capability for small to medium-sized indoor pool installations. With three configurations available, energy-efficient heat recovery, ultra-quiet operation, and construction designed specifically for the harsh swimming pool environment, the DH35 delivers professional-grade dehumidification in a package that’s practical for domestic use.

Upgrade from older Vaporex systems with minimal disruption thanks to dual position LPHW connections, or opt for a complete new installation with the simplicity of the electric heating model. Whichever version you choose, you’re investing in German-engineered quality backed by Dantherm’s reputation for reliability and a comprehensive 2-year warranty.

Protect your pool building, reduce your energy bills, and create the perfect swimming environment with the Dantherm DH35.