August 09, 2018
Raised Rail Prep Tables – Deciding Between Cold Wall vs. Forced Air
I hear this question all the time: “What’s the difference between cold wall and forced air prep tables?” Let’s answer it by looking at each system and examining how it works.
Wrapped Rail (Cold Wall) Conductive Cooling Prep Tables
Wrapped wall prep table systems use copper lines running along the outside body of the food well. The lines form frost to create a cold blanket of air. This results in more consistent and even temperature. No fans or ductwork are required to move the air; therefore, a cold-wall design helps reduce energy-related costs.
Another key feature of this model is its cleanability.
A split-zone prep table unit’s top rail is sealed from the base, allowing it to contain spills and making it easy to clean. There are also no exposed air vents, which is another huge plus. This eliminates the gunk that can build up after a spill which can be difficult to clean and restrict the airflow of the unit, causing performance issues.
Rails with drains make this job even easier, as you can simply dump water into the rail and drain it into a bucket.
Additionally, wrapped wall units allow you to control the top temperature separately from the base of the unit. This split system creates additional energy savings when not in use and offers better control between the top zone and the bottom zone. With a forced air prep table that uses one coil to deliver cold to both areas, you have to compromise one temperature zone for the other. This can result in freezing products in the base or even the coil itself, which means the entire unit is down until it has been defrosted. Using a wrapped wall dual system means you never have to make that choice, because both zones are being cooled independently.
In my opinion, a recessed pan, cold wall, wrapped, conductive cooling prep table is the most effective method for providing a cold blanket of air above pans without using air from the base which can also dry out the food. It delivers cold more efficiently than forced air units, especially in high-heat environments.
Forced Air System Prep Tables
Forced air prep tables rely on air from the base coil being forced above the pan surface area (“air-over”). This often occurs through duct work and/or providing cold air to the pans, but not blowing over the top.
As is the case with most pieces of kitchen equipment, there are pros and cons with forced air units. On the plus side, they are lower in initial purchase price than cold wall designs, but the benefits stop there. Lower upfront price is the only reason most people buy forced air prep tables, as they require more energy to operate, are harder to keep clean and struggle to hold accurate temperatures in both zones.
Continuing with the negative side, forced air prep tables have a number of other issues:
- Ambient air from the room brings an extra heat load and additional humidity as it is circulated back through the base coil. The base cannot keep up with the cooling demand, so the prep table’s temperature must be lowered. This can cause product stored in the base to freeze as well as the coil itself, sending the unit into premature defrost or shutting the coil down altogether.
- The air movement of a forced air prep table can dry out toppings and ingredients. Because pan contents are more influenced by ambient air, freshness can be reduced and waste increased.
- They are more difficult to clean due to the vents and duct work.
- They are more costly in high-heat environments due to increased maintenance issues.
Constantly providing temperatures below 41°F without freezing is the goal of both forced air and wrapped wall prep tables. My recommendation is to always check the ambient conditions of the working environment and to understand the workload of the unit prior to selecting a prep table. Doing so in combination with the information presented above should provide a great guide to making the right choice for any customer and any kitchen.
Chef Steve D'Angelo
Unified Brands Corporate Chef