A carbon monoxide detector in an enclosed car park (basement parking) measures the CO from vehicle exhaust, runs the extraction fans at the right stage and raises an alarm when the concentration passes a safe limit. There are two common approaches: a standalone system that controls the fans directly, such as the Komttech VCO800, or addressable detectors on the fire alarm loop, such as the Honeywell Farenhyt IDP-CO.
This guide compares the two, explains how to split zones and count detectors, how alarm levels link to extraction stages, and what to check in the datasheet and submittal before approval.
Key takeaways
- CO is colourless and odourless and is not picked up by ordinary smoke detectors, so an enclosed car park needs dedicated CO detection.
- The Komttech VCO800 is a standalone panel with 1 to 4 zones of up to 16 VSO-800 detectors each, 4 extraction levels and 4 alarm levels.
- The Honeywell Farenhyt IDP-CO is an addressable UL 2075 listed detector for the loop of an addressable panel such as the IFP-2100.
- The manufacturer rates the VSO-800 at about 200 m² coverage, mounted 1.5 to 2 m high.
- CO detection manages day-to-day ventilation. It does not replace fire detection or smoke control.
In this article
- Why does an enclosed car park need a carbon monoxide detector?
- What do the codes say about enclosed car park ventilation?
- Standalone CO detection system or addressable detector on the fire alarm loop?
- Side-by-side comparison
- How do you split zones and how many CO detectors do you need?
- Alarm levels and extraction fan stages: how does the interface work?
- What to check in the datasheet and submittal
- Inspection, maintenance and CO sensor life
- Common mistakes
- CO detection systems from AZEIDK
- FAQ
- Conclusion
Why does an enclosed car park need a carbon monoxide detector?
CO comes from incomplete combustion of fuel and builds up in poorly ventilated spaces such as basements, tower car parks and mall parking, especially near ramps, queuing areas and at peak hours. People cannot sense it, so continuous measurement is the practical way to know the level.
For context, NIOSH sets a recommended exposure limit of 35 ppm as a time-weighted average and a 200 ppm ceiling, while the OSHA permissible limit is 50 ppm TWA. These occupational health figures help read the scale. They do not replace the set points the designer approves for each project.
The second benefit is energy: instead of running extraction fans at full capacity all day, CO-controlled ventilation runs them in stages according to the measured concentration.
What do the codes say about enclosed car park ventilation?
In Saudi Arabia, mechanical ventilation falls under the Saudi Mechanical Code (SBC 501) and fire protection under the Saudi Fire Protection Code (SBC 801), together with what Civil Defense approves on the project drawings.
As an international technical reference, Section 404 of the 2024 International Mechanical Code (IMC) requires enclosed parking garage ventilation to run continuously or automatically by detectors, cycling between full-on at no less than 0.75 cfm/ft² and standby at no less than 0.05 cfm/ft². The same edition requires the detectors to be listed to UL 2075 and to detect both CO and nitrogen dioxide (NO2), so CO alone is not enough under that edition.
The designer should therefore confirm the edition adopted for the project, the corresponding Saudi clause, and whether NO2 detection is needed alongside CO.
Standalone CO detection system or addressable detector on the fire alarm loop?
Standalone: Komttech VCO800 panel and VSO-800 detector
The VCO800 is the control panel of the Komttech CO detection system for underground car parks. It has one to four expandable modular zones, each with up to 16 self-addressing VSO-800 detectors on up to 1000 m of twisted cable. It reads each detector’s concentration individually, sounds an alarm when safe levels are exceeded and acts directly on the extraction fans. Each zone works independently and can be disconnected while the others stay in service.
The VSO-800 uses a linear NAP-505 electrochemical sensor with a 0 to 330 ppm range, 1 ppm reading accuracy, 200 m² coverage and a 7-year life, and comes with a high base for surface conduit entry.
Addressable: Honeywell Farenhyt IDP-CO on an IFP-2100 panel
The IDP-CO-W is an intelligent addressable detector that meets UL 2075 for system-connected CO detection. Its address is set with rotary switches, so no extra modules are needed for point ID. It offers automatic drift compensation, RealTest CO testing and a 10-year CO cell with end-of-life warning. With a B200S sounder base it produces the Temporal 4 CO alarm pattern.
It goes on the loop of a compatible addressable panel such as the Farenhyt IFP-2100, whose built-in SLC supports 159 IDP/SK detectors and 159 modules, expands to 2100 points and complies with UL 864 10th Edition. The alarm thresholds in the datasheet (70, 150 and 400 ppm with set response times) are the UL 2034 sensitivity limits: they are designed to warn people, not to stage fans.
Side-by-side comparison
| Item | Komttech VCO800 + VSO-800 | Farenhyt IDP-CO on a fire alarm panel |
|---|---|---|
| Main role | Measure concentration and control extraction fans | Addressable CO alarm within the fire alarm system |
| Wiring | 2 x 1.5 mm² twisted cable, up to 1000 m per zone | SLC loop of the addressable panel |
| Capacity | 4 zones x 16 detectors | Per loop and panel capacity |
| Fan control | Direct: 4 extraction levels, 3 voltage-free contacts | Through panel programming and control modules |
| Reading | ppm per detector on the panel display | Alarm status and detector location |
| Listing | Not stated in the manufacturer brochure | UL 2075 |
| Sensor life | 7 years | 10-year cell with end-of-life warning |
| Best fit | Basements, tower and mall car parks | Buildings with addressable fire alarm, boiler rooms, small car parks |
Many projects combine both: a standalone system for ventilation, with its alarm signals passed to the fire alarm panel for the control room.
How do you split zones and how many CO detectors do you need?
Start from the manufacturer’s coverage. At about 200 m² per VSO-800, a 3,000 m² basement level needs at least 15 detectors on area alone, which fits one 16-detector zone. That is a minimum, not a layout. The approved drawing sets the final number after reviewing:
- Ramps, entries and exits: where engines start and idle and CO tends to concentrate.
- Dead corners: areas outside the air path between supply and extract openings.
- Fan grouping: each detection zone should match a ventilation zone served by specific fans, so the panel runs the fans nearest the source.
- Levels: one zone per level works well, so a four-zone panel can serve four levels, and one zone can be isolated for maintenance.
- Cable length: up to 1000 m per zone on 2 x 1.5 mm² twisted cable, per the Komttech brochure.
The VSO-800 mounts 1.5 to 2 m high per the manufacturer, close to breathing level and clear of vehicle impact. The IDP-CO is installed per its installation manual and the approved panel instructions.
Alarm levels and extraction fan stages: how does the interface work?
Per its datasheet, the VCO800 offers 4 extraction levels, 4 pre-selected alarm levels, 4 selectable operating modes and 3 voltage-free outputs, which connect to the fan control panel or VFD according to the ventilation design. Staged operation typically runs: low concentration, fans at minimum or standby; rising concentration in a zone, higher speed for that zone’s fans; sustained rise, full extraction; alarm level, audible alarm and a signal to the fire alarm panel or BMS.
This article does not set ppm values for each stage: they follow the approved design, the applicable code and the manufacturer’s instructions. Above all, program the priority: on a fire alarm the fans must switch to the approved smoke control mode and leave CO control. Smoke control in car parks is covered in our car park fire protection guide.
What to check in the datasheet and submittal
- Range: 0 to 330 ppm for the VSO-800, 20 to 300 ppm for the VCO800 panel.
- Listing: if the specification calls for UL 2075, the IDP-CO is listed per its datasheet; the Komttech brochure states no listing, so confirm before submitting.
- Whether NO2 detection is needed, especially where diesel vehicles park.
- Panel supply: 220 V AC ±10% primary and 24 V DC secondary.
- The interface diagram with the fan panel and fire alarm panel, and the fire priority sequence.
- Sensor life and replacement plan.
Our technical selection of systems and equipment service matches the model to the specification before supply.
Inspection, maintenance and CO sensor life
Electrochemical sensors have a finite life: 7 years for the VSO-800 and 10 years for the IDP-CO cell, which signals end of life and a fault. The IDP-CO compensates for drift automatically and supports RealTest. A maintenance programme should include gas testing per the manufacturer’s instructions, checking that the fans respond at each stage, logging each detector’s reading and replacing sensors before end of life. This can sit within our annual maintenance contracts.
Common mistakes
- Spacing detectors on area alone and ignoring ramps and dead corners.
- One zone for several levels, so every fan runs because of one level.
- Ceiling-mounting the detector like a smoke detector instead of at the manufacturer’s height.
- No fire priority, leaving fans under CO control during a fire.
- Relying on CO alone where the applicable code also requires NO2.
- Leaving sensors in service past their rated life.
CO detection systems from AZEIDK
AZEIDK supplies the Komttech VCO800 panel, the VSO-800 detector, the Honeywell Farenhyt IDP-CO detector and the IFP-2100 panel in Saudi Arabia, within its carbon monoxide and gas detection range and fire alarm solutions. Our team reviews the detector layout, prepares the submittal and handles supply, installation, connection to ventilation or fire alarm, testing and commissioning. Each product page carries the manufacturer datasheet.
FAQ
Does a smoke detector detect carbon monoxide?
No. A smoke detector responds to smoke particles. CO needs a dedicated sensor, such as the electrochemical sensor in the VSO-800 or the CO cell in the IDP-CO.
How much area does a car park CO detector cover?
The Komttech VSO-800 covers about 200 m² per the manufacturer. The approved layout sets the final number after ramps, corners and fan zones are considered.
At what height is a CO sensor mounted?
The VSO-800 mounts 1.5 to 2 m high per the manufacturer. Each model has its own height in its installation manual.
Can a CO detector connect to the fire alarm panel?
Yes. The IDP-CO is addressable and sits on the loop of a compatible panel such as the IFP-2100, and the VCO800 can pass its alarm to the fire panel through its voltage-free contacts.
How long does a CO sensor last?
7 years for the VSO-800 and 10 years for the IDP-CO cell with end-of-life warning, per their datasheets.
Conclusion
Choosing a car park CO detector starts with one question: do you need fan control, a CO alarm within the fire system, or both? Then split zones by level and fan group, count detectors from coverage, and set extraction stages, alarm levels and fire priority in the approved design.
Designing ventilation for an enclosed car park? Send us the drawings and fan zoning, and we will propose the CO detector layout and panel with datasheets. Contact the AZEIDK team
