Tag Archives: High Capacity Dishwashing

Commercial Dishwash/Warewash Design

Designing the Ware/Dish Wash Area:

Efficient and Ergonomic Space/Storage/Systems

This is in reference to everything except for the machine, especially for larger establishments and facilities, this part is as if not more important than the machine itself!

Is there enough ‘set down’ space for the soiled dishes/utensils?

Is there a proper sort scrape system in place, scrape holes in the set down bench or not? The Location of such and the big one, food waste/disposal machines/systems*.

*A subject to cover in detail another time.

Pre rinse sink or sinks, size, basket rack support frame in the sink or not, built in waste trap into the sink drain, remote drain valve opening device (OHS safety no cutting hands with rogue steak knives in bottom of sink!)

Dishwasher basket storage, plenty of and easy access, either under bench racks, or wall racks. Storage of cleaning equipment and chemicals, clothes brushes, scrubbers all need a home, well draining and on the ‘dirty side’ of the line. As do chemicals for the machine and general washing, a small amount will be required at or near the machine and or sink, again on a well draining rack or shelf, the bulk chemical storage will be located elsewhere in a suitably ventilated room away from food stores and preparation.

Clean racks space, in a small operation this may be as simple as allowance for 2 baskets on the exit side of a DW, not 1.5! It’s amazing how many exit benches even entry that are made that simply do not consider the standard requirements of a DW basket or 2!

Larger operations that may have exit rollers may hold many basket racks, and may need to as the operation system may be such that the staff member could be bogged down rinsing and loading dishes at the dirty end at such pace and volume that they don’t get a chance to get to the clean end for a while to sort and stack, if there is insufficient ‘parking space’ the machine will stop (sensor at end of bench tells it to!) and then you can’t load the machine until baskets are cleared. This may mean extending the exit roller bench around a corner to gain more meters, if this is the case the corner roller bench often requires ‘power assistance’ to help the baskets along.

Sorting racks, in larger operations the ability to place racks of cutlery aside onto a shelf for sorting can make a big difference to efficiency of the operation, freeing up valuable ‘parking space’ this can be a simple shelf above the bench that holds the baskets ready for this task.

Finally all these dishes, cutlery and crockery need homes, where possible storage should be provided nearby to allow for bulk stacking in peak times before transfer of the utensils/crockery to their final homes.

You need to have the best possible solution of stacking, sorting, parking and sorting in place with the space available to you to make the most of any machine you have, if you get this part right it can mean a huge difference is labour savings for a larger operation, perhaps one staff member instead of two in peak times.

Warewashing floor plans

typical DW elevated drawings
typical DW elevated drawings


Commercial machines are noisy! The water pressures and volumes are much greater than domestic machines, that after all is how you get a 3 minute wash cycle not 30! It is not ideal to have them near the front of house if it can be avoided, especially larger rack machines. Most manufacturers do have a specification upgrade or model that includes ‘insulated hood/body’ and this is the model that should be selected anywhere where noise or heat is a consideration.

Water Quality:

Know the quality of your water. The main concern it is what is known as ‘hard’ which refers to high levels of minerals in the water, particularly ‘calcium’. On its own all this may do really is show up as a kind of dirty water mark on stainless, fine white lines around water drops stains etc. But when this water is exposed to constant heating such as the boiling/heating tank in the dishwasher, it tends to ‘calcify’ up around the elements in the tank, blocks jets/nozzles etc and can lead to premature element failure also.

If the water quality is poor than a high quality water filter or filters is recommended to be installed onto the incoming water supply, in some remote areas , especially where bore water is used a ‘Reverse Osmosis’ system may be required, which can be expensive. Some people just choose to use and abuse the machine and replace often knowing it will have a limited effective performance life.

Stand Alone Reverse Osmosis Machine

Sufficient Hot Water Supply,

When designing a facility your Hydraulics engineer should be requesting specification details about the machine/s being used and also gain a better understanding of the anticipated use rates and times to meet general use and also peak demands, from this they can establish recommendations for a suitable Hot water system to suit.

The hydraulics consultant/engineer will also require the above information for calculations required for your trade waste requirements.

The small print:

Australian Water Mark:

Quality machines as noted above will have an Australian water mark, sticker/badge fixed to the machine, which means the unit has been through a process of testing and certification to meet Australian plumbing standards, learn more here, http://www.abcb.gov.au/product-certification/watermark


Back Flow Prevention Devices (BFPD):

Normally are incorporated into most machines a BFPD is a type of valve that is connected to the water supply (or is in the machine ) of the machine, its designed to prevent soiled/dirty water being forced back into the freshwater supply line where it could contaminate other fresh/clean water supply lines.

In some local council areas it has been noted that local plumbing inspectors have demanded BFPD be fitted to machines, even where such machines already have such a device either built in and or supplied with the machine. In some cases they specify a particular type of BFPD, which not only is expensive but is supposed to be inspected at least on Annual basis which adds frustration and costs to the business.

It’s something that customers need to be aware of and are normally not, and it’s an extra cost and inconvenience to the business. Your plumber and yourself can dispute it with the local inspector and you may or may not win your argument.

It’s something that your Hydraulics Consultant/engineer may be able to advise you with, again you will need to be able to provide them with full speciation details from the Manufacturer of the machine.

Canopies/Drains and Stainless Steel

Floor drainage, not only is it a requirement to meet Australian Standards to have a ‘draining floor to waste’ on this area it makes perfect safety and hygiene sense. In large facilities with large machines you should be using ‘floor drain troughs’ to cope with such a wet area.

Lower volume operations with pass through machines often a small round floor waste is suffice.

Dishwasher floor trough

To Canopy or Not to Canopy?

When you look at the Australian standards a Pass through Dishwasher generally the answer is YES, even if low KW. However local Authorities often consider the specific situation of its use. For example it is in such a location where the volume is so infrequent that its hardly used, and perhaps a simple ceiling vent may suffice (the steam has to go somewhere!) such a place may be a community hall, where the kitchen only gets used on a Saturday night once every now and then.

Or a small kitchen than opted for a pass through DW instead of an under counter machine for OHS reasons (avoiding heavy tray lifting and bending down). Higher volume Pass through and Conveyor machines its not negotiable. There is a bunch of reasons why the Canopies (Steam condensate hoods) are required, Hygiene, Working conditions and protection of the building materials are some of.

Built in steam condensate hoods, are now available on some machines. These have a filter system built in/on the hood that processes the steam in such a way a canopy id not required. This is great in locations where installing a hood and the duct work associated could be cost prohibitive. They are a more expensive machine, but the savings of the duct and canopy offset the cost.

Commercial Dishwasher Canopy
Commercial Dishwasher Canopy

Stainless Steel.

Generally lots of it! From floor to canopy or ceiling at least behind the Dishwasher and preferably the entire DW/Ware washing area.

You can use tiles which may be ok for lighter duty areas, but the upkeep and cleaning of them isn’t as easy as Stainless steel splash backs in this area. Under shelves should be ‘rack style’ to allow drainage as also for wall shelves, backs with 300mm splash backs well sealed to wall, both at the back and end sections if applicable.

Running Costs:

Saving money with hot air!

A clever energy saver most machines offer is a type of steam condensate/heat exchanger system, where basically a large amount the steam that escapes from the machine is captured and used to reheat water, this reduces energy consumption a lot as you are giving the water heating process a boost from the steam you have already paid to generate!

To Polish or not to Polish?

Totally up to each establishment’s style and type of service. Where once we were taught to polish all cutlery and glasses it’s not always seen as important in today’s age of ‘casual dining/drinking’ However if you’re a busy place 100+ per day and you are paying staff to manually polish cutlery/crockery you need to your maths and consider machines that do it for you. There are ‘cutlery burnishes’ that have tumble your silver ware with a special compound that makes them all shiny and spotless each time, they can be a bit noisy, but cheaper than paying staff to do it!

And for Glasses you should consider upgrading your glass washer to a machine that has a ‘reverse osmosis’ water demineralisation and filtering system either built in or attached, you will get close to ‘spot free washing as you can get and in most cases avoid the expensive chore of ‘polishing’, so it’s just a mathematical question of do I spend a few thousand more on such a machine to save XX$$$ PA in extra wages polishing glassware.

Saving Labour $$$

The other pre rinse method is in the machine itself. Applicable to flight and rack conveyor machines normally, although some high end Pass through systems offer something similar also. It’s normally a section of the DW system that is on before the main rinse body, rinses all the dishes before entering the wash cycle, not as energy efficient as the manual pre rinse, but saves labour dramatically by cutting back on the prep time of the dish washer operator, so in some cases the annual labour savings could offset energy costs.

Some larger systems also offer a ‘dryer tunnel’ section also, effectively a hot air blast as the dishes pass through a great luxury if you can afford it, very costly to run, and given that the dishes are going to be coming out of the machine at +75c minimum they generally air dry pretty well without too much help.

Saving running costs by choice of energy

Whilst not common in Australia, something different to consider, running your machine on Gas or Steam!

Gas is a no brainer on the KW Per Hour costs as you could be running at 6KWPhr instead of 24KPhr as an example, basically the system has a gas hot water heater to generate the hot water instead of electrical. The other great benefit of such a machine is that if a facility does not have enough power available or the costs to upgrade the power to suit it can allow a large capacity machine to be used without bumping up the power requirements.

Steam is even greater economically again, but in Australia almost unheard of these days, but still does happen in the Northern Hemisphere where steam heating systems in large commercial buildings such as hospitals occurs.

Gas Commercial DW