The Vent-Axia Multivent MVDCH is a ventilation system designed for simultaneous extraction from multiple areas within a building, such as bathrooms, kitchens, and toilets. This unit is specifically engineered for continuous 24-hour operation and should not be used in conjunction with a delay timer. Its primary function is to remove humid air and improve indoor air quality.
Function Description:
The Multivent MVDCH operates as an inline ducted unit, positioned between lengths of ducting. It employs a highly efficient backward curved centrifugal motor impeller set to draw air from up to four separate rooms. An integral humidistat automatically triggers an increased airflow (boost cycle) when a humidity level above a set point is detected, effectively removing moisture caused by activities like showering or cooking. The unit is designed to be mounted in roof voids with a minimum height of 250mm and can be installed in three different orientations: base-mounted, vertically mounted, or ceiling-mounted, offering flexibility for various installation scenarios.
Important Technical Specifications:
- Power Supply: 1 Phase Supply (220-240V 50Hz).
- Fuse Rating: The unit should be protected by a 3A fuse.
- Ducting Compatibility: Designed for 125mm ducting, with provisions for 100mm ducting using adaptors.
- Humidity Set Point: Adjustable between 60% and 90% Relative Humidity (RH), with a mid-point potentiometer setting of 75% RH.
- Operating Temperature Range: Ambient exhaust air temperatures should be between -5°C and 40°C.
- Relative Humidity Limit: Not to be installed in areas with relative humidity above 90%.
- Motor Type: Backward curved centrifugal motor impeller set.
- Over-heating Protection: Equipped with Standard Thermal Overload Protection, which automatically switches the fan off in case of a fault condition.
- Stock Reference Number: 18 30 20B.
- Wireless Controller (Optional Extra): Stock Ref. 426035.
Usage Features:
- Automatic Humidity Control: The integrated humidistat continuously monitors ambient humidity. When the RH exceeds the set point, the fan automatically enters a boost cycle. The response varies based on the initial speed setting:
- Low Speed Setting: If high humidity is detected, the fan speed increases to medium for 30 minutes. If humidity is still high after this period, it increases to high for 15 minutes. If humidity then drops, it returns to low; otherwise, it reverts to medium for another 30 minutes.
- Medium Speed Setting: If high humidity is detected, the fan stays at medium speed for 30 minutes. If humidity is still high after this, it increases to high for 15 minutes and then drops back to the original medium speed setting.
- High Speed Setting: If high humidity is detected, there is no speed change. However, after 30 minutes, the boost time-out automatically resets the fan speed back to low.
- Manual Override: In all automatic humidity operating modes, it is possible to override any humidity cycles in progress and switch the fan to any other speed using the optional wireless controller. However, if high humidity is still present, the unit will revert back to the appropriate automatic humidity cycle operation.
- Wireless Remote Control (Optional): An optional hand-held wireless transmitter allows for remote control of the fan speed (low, medium, high/boost). The transmitter has a range of at least 10m through concrete block/beam floors and features 16 unique code selection options to prevent cross-talk between multiple installations. Multiple transmitters can be dedicated to a single Multivent unit, and vice versa.
- Condensate Drain: The unit is designed to handle moisture-laden air and includes a condensate drain. The location of the drain varies depending on the mounting orientation (on the unit housing for base/vertical mount, under the lid for ceiling mount). Additional drainage may be required for certain configurations.
- Flexible Installation: Can be mounted in three orientations (base, vertical, ceiling) to suit different roof void configurations and ducting layouts.
- Ducting Connections: Spigots are provided for connecting intake and exhaust ducts. For 100mm ducting, the center of the spigot cap can be removed.
Maintenance Features:
- Accessibility: Installation and maintenance require adequate access to the unit.
- Thermal Overload Protection: The motor's built-in thermal overload protection helps prevent damage from overheating. In case of activation, the unit should be isolated, checked for obstructions, allowed to cool, and then reconnected. If the issue persists, a service engineer should be contacted.
- Cleaning: While not explicitly detailed, regular inspection of ductwork and the unit for obstructions is implied by the over-heating protection instructions.
- Wiring: All wiring must comply with current I.E.E. Regulations and be performed by a qualified person. The unit must be earthed, and a local double pole isolator switch with at least 3mm contact separation is required.
- Battery Replacement (for optional wireless controller): The battery compartment cover on the back of the transmitter unit can be removed to replace the PP3 9V battery.
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