Pass through dishwasher buying guide

The potential rewards in terms of efficiency saving are far greater with these powerful, rapid washing units. However, even more than with a frontloading dishwasher, a commercial pass through dishwasher system represents a significant investment for any commercial catering operation and is not a purchase to undertake lightly, or without doing at least some basic research.

Prior to reading the specific purchasing advice for pass through systems, we strongly recommend you look at our essential advice for the purchase and installation of all warewashers, which covers the following key areas.

• Break tanks and WRAS legal requirements
• Servicing valves
• Water pressure
• Drain pumps
• Requirement for a water softener
• Type of water softener
• Electricity supply
• Hot vs cold water supplies

Once you're satisfied you understand the minimum requirements of your washer purchase, you can take a closer look at the specific guidance for a pass through or rack conveyor dishwasher system. Catering Appliance Superstore makes this easier with our pass through dishwasher buying guide

Size, dimensions, and positioning

Naturally, one of the first things you will check is the location the system will be installed and the dimensions of the pass through dishwasher, to determine whether you have room for it. Remember, although the external dimensions of the washers themselves are clearly listed on the Catering Appliance Superstore product pages, you will want a total width, depth and height for the full dishwasher array, including any loading tables, pre-wash sinks or draining racks. You'll also need to check the height and any aerial obstructions more carefully than if you were purchasing a smaller front loading commercial dishwasher.

One major advantage of pass through dishwasher systems is that there is no door that needs to be opened; instead a wash hood is moved up and down or the crockery and cutlery trays are passed through on a conveyor. Because of this they're often easy to keep loading and unloading without having to stop to let members of service staff past.

If you don't have enough continuous space for a pass through washer system and all the associated sinks and draining surfaces, don't worry. Pass through systems supplied by Catering Appliance Superstore are available as corner fit units, making the most of the space you have.

Capacity and type of unit

The hourly wash capacity of pass through dishwashers is impressive, not necessarily because of any extra space for cookware (although they can have a lot more vertical space for tall items), but because of the speed each load is completed. Drop down hood washers like the Classeq P500AD-12 use up to twice as much power as an equivalent front loaded unit, while rack conveyor systems like the Hobart Ecomax C805A can use a huge five times as much power. All that extra energy isn't wasted, it's going into washing dishes really quickly.

When calculating wash capacity of a hooded pass through dishwasher, multiply the maximum capacity of 18 plates by an average washes per hour. 18 to 20 is a reasonable estimate based on a cycle of 3 minutes, but some models allow variable wash cycles (see below) that can speed operation up even more. Also check for those with auto start hoods for even quicker turnaround.

The Hobart Ecomax rack conveyor systems stocked by Catering Appliance Superstore are really the next step up from drop down hood dishwashers - they operate continuously and depending on the unit and the settings applied can wash up to 150 racks per hour - that's 2700 plates.

Additionally, where calculations of wash capacity for front loading dishwashers need to include about 30 seconds for loading and unloading, you can cut this down to 10 or even 5 seconds for a pass through washer, or nothing for a conveyor system which runs continuously. Over the course of days, weeks and months this makes a huge difference.

Variable cycle selector

For hooded passthrough dishwashers, having the flexibility to vary the cycle time to cater for quick wash items or more difficult to clean cookware is an extremely useful feature.

Energy efficiency features

Although pass through systems already use a lot more power and a bit more water than front loaded washers, in terms of the amount of washing they do they are far more efficient and more cost effective "per plate" if your commercial catering business produces enough washing up to justify them.

As with any other range, there are additional features to look out for to further improve energy efficiency. Look for low volume wash tanks and rinse tanks, double skinned body and hood construction, and insulated boiler.

Power requirements

Where most front loaded commercial dishwashers and glasswashers are supplied as single phase with some available in a three phase power option, pass through systems have greater power requirements and are more often supplied as three phase as standard. Some but not all can still be purchased as single phase, but this must be specified. Regardless, their requirements for power are greater than many other appliances, so make sure you check our guide to electric supply for commercial appliances to ensure you have enough capacity on your power circuit and the right kind of supply.

We've already mentioned that the rack conveyor systems use a lot of power, so if you won't use them to their full potential (will you consistently go through over 2000 plates an hour?) we recommend a hood washer as the pass through system for your catering operation. Of course if you think you might go through this many, the opposite advice is true.

Additional components of your passthrough system

Don't forget that the dishwasher itself is only the main component of your passthrough system, not the whole system. To get a really efficient dishwasher area set up you will need tables before the wash for stacking plates and other crockery, and space for racking up on the crockery trays. A pre rinse sink with a jet tap before the wash is also a good idea to keep your dishwasher free of debris, and then after the washer you will need an area from cooling and drying.

For a continuously operational conveyor system these areas need to be large enough to avoid the risk of the whole production line backing up, and some thought will need to go into how the system is staffed.

Many of these items are supplied as part of the dishwasher range by the manufacturer, to ensure they fit perfectly with the dimensions of their washer. You can however purchase general purpose units providing height is correct and you have sufficient width for trays to slide in and out of the dishwasher easily.