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How to Monitor 18 Fridges and Freezers Across Five Locations with Wireless Sensors
One faulty refrigerator can be a local problem. Eighteen fridges and freezers across five locations can become a visibility problem.
For organisations that store temperature-sensitive products, checking each appliance by hand is slow, inconsistent and hard to audit. A staff member may record a temperature during business hours, but that does not show what happened overnight, during a public holiday, or during a short power issue. It also does not help much when the asset sits at another site.
ProSense developed a wireless temperature-monitoring architecture for an organisation that needed practical visibility across 18 refrigerators and freezers at five separate locations. The proposed system used Monnit wireless temperature sensors with probes, local gateways and the iMonnit monitoring platform.
The aim was simple: give authorised users a central place to view temperatures, review history and receive alerts before a temperature excursion turns into a bigger issue.
Why multi-site refrigeration needs a different approach
Manual temperature logs can work for a small site with one or two appliances, especially when risk is low and access is easy. The challenge changes when refrigerators and freezers are spread across multiple locations.
With 18 assets across five sites, several questions become harder to answer:
Which fridges are currently within the required temperature range?
Has any freezer drifted out of range after hours?
Are there repeated temperature swings on one appliance?
Can records be produced for an audit or internal review?
Who receives alerts when a problem occurs at a remote site?
Can access be shared without giving everyone the same level of control?
The issue is not only the number of fridges. It is the combination of distance, time and record keeping.
A refrigerator at one location may be managed by different staff than a freezer at another. Some sites may be visited daily. Others may not. A local alarm on an appliance is useful only if someone is near enough to hear it and knows what action to take.
Wireless monitoring changes the model. Instead of treating each refrigerator or freezer as a separate asset with its own manual process, each one becomes part of a common monitoring platform.
The proposed architecture for 18 refrigeration assets
The ProSense architecture grouped each refrigeration asset into a wireless monitoring system built around three main parts.
System part | Role in the monitoring setup |
Monnit wireless temperature sensor with probe | Measures the temperature inside each refrigerator or freezer |
Local Monnit gateway | Receives wireless sensor data at each site and passes it to the monitoring platform |
iMonnit platform | Displays live readings, stores history and manages alarms and user access |
Each fridge or freezer would have a dedicated temperature sensor and probe. The probe sits where the temperature reading is needed, while the wireless sensor transmits readings to a local gateway.
The gateway acts as the connection point for that site. It receives readings from nearby sensors and sends them to iMonnit, where users can see all monitored locations from one platform.
This structure suits a multi-site setup because it keeps the field hardware simple. Each location needs suitable sensors for its refrigeration assets and at least one local gateway, subject to the site layout and wireless range requirements.
The cloud-based platform then brings everything together.
How the sensors work inside fridges and freezers
A wireless temperature sensor with a probe is well suited to refrigeration monitoring because it separates the electronics from the sensing point.
The temperature probe can be placed inside the refrigerator or freezer, while the sensor body can be positioned where it can communicate reliably with the gateway. This matters because refrigeration cabinets can disrupt wireless signals, especially when metal construction, insulation, doors and stock placement are involved.
The exact probe placement should match the monitoring goal. For example, a facility may want to monitor the general air temperature inside a refrigerator. In some cases, a buffered probe or product-simulating placement may be more suitable, depending on the application and compliance expectations.
For medical, food, refrigeration and facilities applications, the key principle is the same: measure the temperature that best represents the risk being managed.
A good installation plan should define:
Which appliance each sensor belongs to
Where the probe is placed inside the cabinet
How the cable exits or passes through the appliance
Where the sensor body is mounted
How readings will be named in the platform
What alarm thresholds apply to each asset
That naming step sounds small, but it matters. In a five-site system, “Freezer 1” is not enough. A clearer label such as `Site 3 Pathology Freezer 1` or `North Kitchen Upright Fridge` helps users respond quickly.
How gateways connect each location
The gateway is the bridge between the local sensors and the iMonnit platform. In a five-location deployment, each site would typically have its own gateway so that local sensor data can reach the platform without relying on another site.
This approach keeps each site independent. If one location has a network issue, it should not stop another location from reporting. It also makes the system easier to expand because new assets can be added at the relevant site rather than redesigning the whole network.
Gateway placement should be planned rather than guessed. The best position depends on the building layout, appliance locations, construction materials and the distance between sensors and the gateway.
A practical commissioning process would usually include:
Map the assets
List all 18 refrigerators and freezers, grouped by site.
Check wireless paths
Review the physical distance and likely obstructions between sensors and the gateway.
Place gateways in suitable locations
Choose locations that support stable communication and practical access.
Assign sensors to assets
Pair and name each sensor clearly in iMonnit.
Test readings
Confirm that every sensor reports to the platform from its installed position.
Test alarms
Check that email and SMS alerts reach the right people.
For a multi-site refrigeration monitoring project, this planning stage is what makes the system useful rather than just connected.
What iMonnit adds beyond local readings
A local display can show what is happening near one appliance. A monitoring platform shows what is happening across the whole network.
With iMonnit, the proposed architecture provides a pathway for centralised temperature visibility. Authorised users can view the state of all monitored fridges and freezers through a common system, rather than calling each site or waiting for a daily log sheet.
The platform also supports historical records. This is useful when someone needs to understand whether an out-of-range event was short, repeated or linked to a wider issue. For example, a freezer that warms slightly every afternoon may point to door-opening patterns, defrost cycles, loading practices or equipment performance.
Historical data helps teams shift from “What is the temperature now?” to “What has been happening over time?”
Useful records may include:
Current temperature readings
Time-stamped history
Sensor status
Alarm events
Acknowledgements or response notes, where configured
Trends that can support maintenance decisions
The system can also provide configurable email and SMS alarms. That allows alarm rules to match the risk profile of each asset. A medical refrigerator, a food storage freezer and a facilities spare fridge may not need the same thresholds or escalation contacts.
Setting alarm rules that people can act on
Temperature alarms are only useful when they are clear, timely and sent to the right people.
Too few alarms can leave problems unnoticed. Too many alarms can train people to ignore them. A good system design sets rules that match each appliance, product type and operational process.
Alarm planning should cover several points.
Temperature limits should match the application
Medical, food and refrigeration facilities may have different acceptable ranges. These limits should come from the organisation’s own requirements, relevant standards, product guidance or internal procedures.
The monitoring system should reflect those requirements, not invent them.
Delay settings can reduce nuisance alerts
A refrigerator door opened briefly during normal use may cause a short air temperature change. Depending on the application, an alarm delay may help reduce unnecessary alerts while still catching meaningful events.
The delay should be chosen carefully. A high-risk freezer may need faster notification than a general-purpose fridge.
Escalation paths should be clear
An alert should tell people what has happened and where. It should also fit an agreed response process.
For example:
Site staff receive the first alert during business hours
A facilities contact receives alerts after hours
A manager receives escalation if the issue remains unresolved
Technical support or refrigeration contractors are contacted according to internal procedure
This is where multiple user access in iMonnit becomes helpful. Different authorised users can view the assets relevant to their role, while central staff can keep visibility across all five sites.
Making the system easier to manage over time
A wireless architecture is useful because it can grow with the refrigeration fleet.
If the organisation adds another refrigerator at one location, a new sensor can be added and named in the platform. If a sixth location comes online, a gateway and sensors can be planned for that site. The monitoring approach remains consistent, even as the number of assets changes.
That is a major benefit compared with isolated local solutions. A standalone thermometer, local buzzer or paper log may solve one narrow problem. It does not create a shared monitoring model across locations.
To keep the system manageable, ProSense would treat setup details as part of the design, not an afterthought.
A good multi-site structure should include:
A clear asset naming convention
Site-based grouping in the platform
Defined user access levels
Documented alarm thresholds
Agreed alert recipients
Sensor maintenance and battery checks
Periodic review of historical data
A plan for adding new assets
The goal is not only to install sensors. The goal is to create a monitoring arrangement that staff can trust and maintain.
Where this architecture fits best
The proposed system suits organisations that need more than a spot check but do not want the complexity of hard-wired monitoring at every appliance.
It is especially relevant where refrigeration assets are spread across sites and where records matter.
Common applications include:
Medical storage
Refrigerators and freezers used for temperature-sensitive supplies, samples or materials.
Food storage
Cold rooms, upright fridges, display refrigeration and freezers where product condition and audit trails matter.
Refrigeration service
Monitoring that helps identify repeated temperature excursions or equipment behaviour between service visits.
Facilities management
Shared oversight of refrigeration assets across buildings, branches or remote service areas.
The same pattern can also support mixed sites. One location may have medical refrigerators, another may have food storage freezers and another may have general facilities refrigeration. Each asset can be monitored with its own name, thresholds and alert settings while still reporting to the same platform.
What success looks like
A successful deployment does not require staff to stare at a dashboard all day. It gives them confidence that the system is watching the right assets and will alert the right people when readings move outside set limits.
For the 18-fridge, five-location requirement, the ProSense architecture provides a clear pathway to:
Centralised visibility across all refrigeration assets
Temperature history for review and reporting
Configurable email and SMS alerts
Access for multiple authorised users
Site-by-site expansion as new assets are added
Less dependence on manual checks alone
The practical value comes from the full system working together. Sensors collect readings. Gateways connect each site. iMonnit gives staff a shared place to view, review and respond.
When refrigeration is spread across several locations, the monitoring system should not be fragmented. A wireless architecture gives each fridge and freezer a place in one common view, making daily oversight easier and response faster when conditions change.
