So you think you know about… Warewashers

Warewashing is the collective industry name for dishwashers and glasswashers. It derives its name from glass "ware" and table "ware".

Ideally, there should be separate machines for dishwashing and glasswashing. Small establishments cannot justify the cost of a dedicated glasswasher and dishwasher, but there are problems in using the same machine for both. The wash time for glassware is very short, so putting glasses in with the longer wash cycle needed for tableware wastes energy.

Food debris from tableware can easily cause smears and spots on glassware, leading to the need for hand finishing or rewashing. Even putting glasses in the washing machine on their own following a tableware washing cycle can produce soiled glassware. Dishwashers are often programmed to perform a pre-rinse cycle to clear loose food stuck to plates and may have a finishing hot rinse to aid sanitisation.

These are the types of machine available:

Glasswashers
Glasswashers tend to be front-loading, compact machines for small to moderate usage of glassware, often fitting under a counter or on a bench in the dishwash area so the same person can process both glasses and dishes. A busy bar operation would need something bigger and faster, most probably a pull-down hood machine with racking on either side of the unit. The wash cycle is continuous and very fast. As one rack is being loaded, another is being washed.

There is not a great deal of difference in construction between a glasswasher and dishwasher except that wash-cycle settings are a lot quicker on glasswashers and wash temperature options lower than on a dishwasher as there is less soil to get rid of.

An endemic problem with glasswashing is streaking. These scummy streaks can be caused through food residues if both glasses and dishes are being washed in the same machine. Even if glasses are washed in a completely separate cycle following dishwashing, there may still be enough residual food debris left in the wash tank to show on glassware. However, the most usual cause of streaking on glassware is dissolved salts in the water supply, always worse in areas where there is hard water.

Every warewashing machine should have a water-filtration system fitted to the water intake. The type and cost will be dictated by the hardness of the water. Even in parts of the country with the hardest of water it should be possible to minimise streaking from dissolved water salts through fitting the right type of water filter. But restaurant staff laying up tables with wine glasses should still be trained to look for streaks and hand-polish with a cloth or return to the dishwash if necessary.

Cabinet dishwashers
Dishwashers also start with compact machines, which look and work in a similar way to glasswashers and are designed to fit under a counter or on a bench in a back-of-house cleaning area, still room or satellite kitchen.

Pull-down hood machines
The next level in machine design is the pull-down hood dishwasher. These are more powerful and faster and are manually loaded with a basket of soiled tableware. Often they are configured with stainless-steel tabling either side of the washer, so while one basket of dirty tableware is being washed, another is being loaded ready to go in, and a washed basket on the other side is being emptied. This gives a continual cycle of plate washing.

Rack conveyor dishwashers

These work on a pass-through system where the soiled tableware is manually scraped then loaded on to a conveyor belt with plate holders and cutlery baskets. The crockery then passes through different washing zones, which typically start at pre-rinse, go to hot wash and then hot rinse. The dishes come out on the other side of the conveyor ready for stacking.

Flight dishwashers
These are semi-automatic systems, similar in principle to rack conveyor machines, but much bigger. They are designed to cope with huge volumes of soiled tableware such as those found in a hospital kitchen. Depending on size, they can take plates with food residue still on, cutlery and trays.

Staff are at either end of the unit, either scraping and loading the conveyor belt with dirties or taking the cleaned tableware out. Food is prewashed from plates and collected in a dewatering unit so that only the food is held back for waste disposal. Cutlery can be magnetically removed from meal trays to prevent it disappearing into the food waste, and the whole operation needs minimal staff. These machines are normally custom-built to fit the warewashing area and the scale of the operation.

Utensil washers

A kitchen which generates a lot of heavily soiled cooking pots may wish to install a utensil washer. There are two principal systems available. One is similar to a dishwasher, but using very powerful detergents and spray jets that pound the soiled cookware. The other system combines water and detergents with tiny plastic granules which bombard the cookware, producing an abrasive effect that can remove even the worst burnt-on food residue.

Detergents: a primer

Dishwasher detergents are not all the same, and using the wrong type will result in the dishwasher underperforming. A detergent should be able to clean whatever is put through it in a single pass.

All detergents and rinse aids are formulated to take account of water hardness. While a dishwasher should always have a water softener fitted, not all do. Detergents for hard-water areas contain a water-softening agent.

Although many kitchens choose to put glasses through the dishwasher with the tableware, using a detergent formulated for tableware, glassware should really only be washed using glassware detergent. Using tableware detergents to wash glasses will lead to etching on the glass, that familiar fogginess that renders fine glassware unusable and brittle.

All detergent suppliers offer a general-purpose detergent, but there are some specialist detergents. A problem for businesses with a high throughput of teacups is staining from the tannin in the tea. If this is a problem, then detergents containing chlorine are available to remove the stain. Utensil washers need a metal-safe detergent, which has corrosion inhibitors to stop the detergent attacking the metals.

Wash performance is not the only way to assess the value of detergents. Cheaper detergents usually require higher dosing levels than more expensive and powerful detergents. The annual cost of detergents in a busy kitchen is considerable, and the dosing controls need to be set professionally after measuring water hardness, type of product going through the dishwasher and the general level of soiling. Good detergent manufacturers usually offer machine set-up as a free service.

Let's get technical

Which size of machine is for me? Many businesses underestimate the capacity of warewashing machine they need. The big mistake is to look at the overall daily throughput and base the choice on that. This is to ignore the fact that there are always peak demand times in the day. Also, buying a machine for current needs makes no allowance for an increase in business. The safest way to avoid buying the wrong size of machine is to ask manufacturers or distributors for advice.

What are the little extras? Pre-scraping and rinsing saves on chemicals, lessens the risk of food residue remaining after washing, and keeps the wash water cleaner.

A hose reel with a powerful spray or a rotating brush with an inbuilt water spray mounted over a sink with a food debris filter system are the two most popular mechanised methods of pre-rinsing.

What technical questions should I ask before buying?

• There are strict national regulations on how warewashers should be connected to the water main to prevent contamination of the water supply through accidental backflow of dirty water. Some cheaper machines may not fully comply, which could lead to costly modifications later.
• Ask about the type of steel. All warewashing machines offer stainless-steel wash tanks, but there are different grades used in manufacture. The best is grade 304, much more corrosion-resistant than the cheaper, 430-grade stainless steel, though both look the same.
• Ask about noise and heat emissions. Double-skin casings will reduce noise and operating cost and be cool to the touch.u Study the energy and water consumption performance. What may seem a cheap machine to buy could prove to be an expensive machine to run.
• Ask for advice on the fitting of a water-treatment system to prevent limescale build-up in the internal pipework of the machine. Water treatment is essential in hard-water areas.
• Be specific about the availability of spare parts, the turnaround time for spares and the service options offered with the machine. One of the most expensive components on a washing machine is the pump, and it is also one of the commonest sources of breakdown. Invariably, cheap machines are built with cheap pumps. Cheap, that is, until it goes wrong.
• Many of the cheaper machines, mostly coming into the UK from southern Europe, are without spares back-up - frustrating to the restaurant that discovers its super deal has turned into a nightmare when the dishwash grinds to a halt and the service companies shake their heads.

How do I find out more?

CESA (Catering Equipment Suppliers Association)
Tel: 020 7233 7724
E-mail: enquiries@cesa.org.uk
Web: www.cesa.org.uk

CEDA (Catering Equipment Distributors Association)
Tel: 01274 826056
E-mail: secretary@ceda.co.uk
Web: www.ceda.co.uk