Vent-Axia 403837 Lo-Carbon Tempra SELV LHTP Heat Recovery Unit – Long Cell with Humidistat, Timer & Pullcord
The Vent-Axia 403837 Lo-Carbon Tempra SELV LHTP Heat Recovery Unit is a compact, energy-efficient through-the-wall ventilation system designed to improve indoor air quality while reducing heat loss. Featuring Safety Extra Low Voltage (SELV) operation, an integrated humidistat, overrun timer, pullcord control and extended 460mm cell, this decentralised mechanical ventilation with heat recovery (dMVHR) unit provides an effective solution for bathrooms, kitchens, toilets and utility rooms.
Designed to fit a standard 100mm diameter wall opening, the Tempra SELV LHTP is particularly suitable for residential refurbishment, social housing and extractor fan replacement projects. Its compact heat exchanger achieves up to 78% temperature efficiency, recovering warmth from outgoing air to help maintain comfortable indoor temperatures and reduce ventilation-related energy loss.
Key Features
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Safety Extra Low Voltage (SELV): Extra-low-voltage design for applications requiring SELV ventilation equipment.
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Integrated Humidistat: Automatically responds to increased humidity levels, helping control condensation and excess moisture.
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Overrun Timer: Allows extraction to continue after activation, helping remove residual humidity, odours and stale air.
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Pullcord Control: Convenient manual operation when additional ventilation is required.
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Up to 78% Heat Recovery: Efficient heat exchanger recovers warmth from extracted air to help reduce heat loss.
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Extended 460mm Cell: Suitable for external wall thicknesses between 321mm and 460mm.
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Continuous Ventilation: Selectable extraction rates of 6 l/s or 9 l/s, with boost extraction up to 15 l/s.
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Low Energy Consumption: Efficient Lo-Carbon EC/DC motor consumes as little as 3.2W at trickle speed.
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Quiet Operation: Low-noise performance of approximately 20dB(A) at the lowest operating setting.
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Compact 100mm Installation: Fits standard 100mm diameter wall openings, making it suitable for replacing conventional extractor fans.
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Summer Extract Mode: Manual extract-only setting helps prevent unwanted heat recovery during warmer weather.
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IPX4 Rated: Splash-resistant construction for suitable bathroom and utility room installations.
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Easy Maintenance: Accessible heat exchanger simplifies routine cleaning and servicing.
Energy-Efficient Heat Recovery Ventilation
The Vent-Axia Lo-Carbon Tempra SELV LHTP uses an integrated heat exchanger to transfer warmth from outgoing stale air to incoming fresh air. With temperature efficiency of up to 78%, the system helps minimise heat loss while maintaining effective ventilation and improving indoor air quality.
The unit offers selectable continuous extraction rates of 6 l/s or 9 l/s, with a boost rate of 15 l/s when increased ventilation is required. For intermittent extraction applications, the unit can be configured to operate at 15 l/s.
Its airflow arrangement maintains slight negative pressure within the ventilated room, helping prevent humid air from spreading into adjoining spaces. This makes it particularly useful for moisture control in bathrooms, kitchens and utility areas.
Automatic Humidity Control with Timer and Pullcord
The Vent-Axia 403837 Tempra SELV LHTP combines three convenient ventilation controls to provide flexible operation and effective moisture management.
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Built-in Humidistat: Detects increased humidity and automatically activates additional extraction to help reduce condensation and moisture build-up.
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Overrun Timer: Keeps the ventilation operating after the activation signal has ended, allowing additional time to remove humid air and odours.
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Pullcord Control: Provides convenient manual activation of ventilation when required.
These combined functions make the unit particularly suitable for bathrooms, shower rooms and utility spaces where humidity levels can fluctuate throughout the day.
SELV Operation for Suitable Bathroom Installations
The Safety Extra Low Voltage configuration makes the Tempra SELV LHTP suitable for applications where extra-low-voltage ventilation equipment is specified. This provides additional installation flexibility in moisture-prone environments, subject to the manufacturer's installation requirements and applicable electrical regulations.
Its IPX4 rating provides protection against splashing water, making it suitable for appropriately specified bathroom and utility room applications.
Low-Energy and Quiet Performance
Equipped with a high-efficiency Lo-Carbon EC/DC motor and twin impellers, the Tempra SELV LHTP consumes as little as 3.2 watts at its lowest continuous extraction setting. This energy-efficient design helps reduce running costs in applications requiring regular or continuous ventilation.
With operating noise levels as low as 20dB(A), the unit provides discreet ventilation while helping maintain a comfortable and peaceful indoor environment.
Ideal Applications
- Bathrooms and shower rooms requiring humidity-controlled ventilation
- Toilets and WC facilities
- Domestic kitchens requiring extract ventilation
- Utility rooms and laundry areas
- Social housing and residential developments
- Property refurbishment and renovation projects
- Replacement of existing 100mm wall-mounted extractor fans
- Installations requiring SELV heat recovery ventilation
- Properties requiring automatic humidity control with timer and manual operation
Technical Specifications
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Manufacturer: Vent-Axia
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Product Code: 403837
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Product Range: Lo-Carbon Tempra
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Model: SELV LHTP – Long Cell with Humidistat, Timer and Pullcord
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Ventilation Type: Decentralised Mechanical Ventilation with Heat Recovery (dMVHR)
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Electrical Design: Safety Extra Low Voltage (SELV)
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Installation Type: Through-the-wall
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Duct Connection Size: 100mm diameter
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Long Cell Length: 460mm
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Suitable Wall Thickness: 321–460mm
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Heat Recovery Efficiency: Up to 78%
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Continuous Extraction Rate: 6 l/s or 9 l/s
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Boost Extraction Rate: 15 l/s
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Minimum Power Consumption: 3.2W
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Noise Level: As low as 20dB(A)
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Motor Type: Lo-Carbon EC/DC with twin impellers
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Humidity Control: Integrated humidistat
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Timer Function: Overrun timer
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Manual Control: Pullcord
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Summer Mode: Manual extract-only operation
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IP Rating: IPX4
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Applications: Bathrooms, kitchens, toilets and utility rooms
Simple Installation and Maintenance
The Vent-Axia 403837 Tempra SELV LHTP is designed for installation through an external wall using a standard 100mm diameter opening. Its extended 460mm cell accommodates wall thicknesses from 321mm to 460mm, making it particularly suitable for properties with thicker external walls.
The compact heat exchanger allows the unit to replace many traditional 100mm extractor fans while delivering the additional benefits of heat recovery ventilation. Its straightforward construction and accessible heat exchanger also simplify routine maintenance and cleaning.
The Lo-Carbon Tempra range is designed to meet the performance requirements for continuous extract ventilation under Building Regulations Approved Document F, subject to correct installation and system configuration. SELV electrical connections must be installed in accordance with the manufacturer's instructions and applicable electrical regulations.
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