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Equipment: Saving energy while you wash

15 June 2006
Equipment: Saving energy while you wash

The role of mechanised warewashing is to reduce labour costs, but rising utility bills now make machine usage of energy, water and chemicals significant balance sheet items in their own right. As a result, suppliers increasingly promote eco-friendly features as standard items rather than extras.

A good example is the four-sided fully enclosed hood now fitted to Hobart pass-through dishwashers. Traditionally, hoods have had a three-sided design, allowing clouds of steam to spill out on every unloading. The box-like enclosure of Hobart's four-sided hood retains a lot more of the heat, amounting to an estimated 3kW. Standard insulation in the hood gains a further 500W.

Some of Hobart's cabinet machines also have higher doors and internal fittings, which permit double-stacked racking (virtually doubling the quantity of ware that can be handled per cycle) with only marginal increases in change-over times and utility costs.

However, some fitments still require extra investment, as with optional drain heat recovery on Hobart pass-through models. Units consist of two water pipes coiled together: one pipe takes the hot water discharged to the drain on each cycle and also heats up the adjacent pipe, where fresh cold water is flowing in the opposite direction into the rinse boiler. This simple exchange can have a dramatic effect, reducing energy consumption by up to 9kW and helping lower peak load tariffs by corresponding reductions in electrical loading.

The snag with such fitments is that two different financial regimes are applied by many buyers, with the screwing down of purchase price gaining priority over running costs. But Hobart says there has been a significant change in attitude and estimates that about half of its pass-through buyers now specify drain heat recovery, which represents an increase of 50% over the past five years. "During the life of the machine that simple bit of technology will, on running costs alone, pay for the equipment," claims Ian Garner, managing director of Hobart UK.

Smaller throughput
The same arguments don't always wash where throughputs are more modest, however.

Miele Professional specialises in fresh-water cabinet washers. Cycles are two to four times longer than on recirculating water machines, with higher water consumption. Malcolm Martin, marketing manager at Miele, concedes that the benefits lie in better hygiene rather than reduced running costs.

"But for a gastropub or a B&B, it is often not cost effective to do just a couple of cycles on a standard recirculating tank machine," he points out. "You have to fill up the tank and bring it up to temperature. If you have only a small amount of ware to wash, a fresh-water machine is a cost-effective way of doing it." But he concedes that it is less suitable for 60- to 80-cover applications needing fast turnaround. Miele plans to bring out a model to bridge this gap later this year.

"A publican turning over £150,000-£250,000 per year and with two years remaining on the lease doesn't want to spend any more than he has to," says John Nelson, managing director of Nelson Dish and Glasswashing. His policy over the past three years has been to offer all machines at basic, stripped-down prices, letting purchasers add on features to suit.

"In practice this has worked very well with machine price kept low and nobody ‘over-sold'," he points out. Even so, the main optional extras are now specified in about 80% of Nelson sales. These include double-skinning of the main tank, which entails wrapping a second stainless steel sheet around the basic tank with insulation in between. This adds from about £100 to the price of a small washer. A further £100 is required if the user opts for a specially moulded shallow tank that reduces the amount of water needed.

Adding two chemical dosing units adds a further £150 but avoids the extra effort and inconsistencies of doing the job by hand. "Without precise dosing, users err on the side of generosity and subsequently waste a lot of money unnecessarily," Nelson points out. On a dishwasher used for two sessions a day, the savings achieved by a good-quality detergent dosing system should readily achieve savings of between £150 and £200 per year, he reckons.

Nigel Westall, sales and marketing director of Classeq, believes there is a fundamental argument for machines that need minimum amounts of water. "If there is less water in the tank, there is less power needed for heating, less detergent for each wash and less fresh water needed for rinsing," he says. Classeq's approach is to make the surface area of the tank as small as possible. The overall dimensions on the company's current models are now half what they were a few years ago. Thus the Eco glasswasher now has an 18-litre tank, down from 33 litres, with fresh water consumption reduced from 3.5 to 3 litres per cycle. Duo dishwashers are even smaller, at 10 litres. Machine electrical loadings are not significantly lower but having less water to heat cuts energy consumption per cycle.

Simon Aspin, commercial director of Winterhalter, maintains that improved water quality is the best way to reduce costs. "The more you can recycle your wash water, the less water, chemicals and energy you use," he points out. This highlights the importance of continuous water filtering and has also brought a big increase in caterers specifying water softeners.

Winterhalter's TE machines, which have integral water softeners, adding about £500 to machine price, now account for more than 80% of the company's sales of such machines - about three times the number compared with five years ago. "It all adds up," Aspin concludes. "If you don't fit a softener you have to factor in the cost of extra service call-outs, because of limescale build-up, plus the cost of the extra electricity required as the elements scale up."

Life costs Warewasher life costs have recently received attention from Enodis UK Food Service Group, with several energy-saving features as standard on the completely updated range of Masterwash warewashers it announced this month. The range now extends to glasswashers and pass-through machines, as well as front-loading dishwashers and features double-skinned tanks, water-saving wash chambers requiring only 10 litres to fill and front-filters designed to keep water cleaner for longer.

The effects of heat recovery tend to be most tangible on large multi-tank machines. The "energy saver" option now available on Baron rack-and-flight-type dishwashers saves up to 20kW on the largest models as well as reduced steam and heat emission into the kitchen, according to the manufacturer. The system converts hot steam from the exit of the dishwasher into a water heating process to raise the temperature of the incoming water. Roger Flanagan, managing director of Baron's UK distributors, Universal Food Service Equipment, believes that it won't be too long before similar systems will be created for smaller machines.

While it is now common on larger multi-stage machines to transfer water between sections, Electrolux has taken a different approach on its latest rack-type machine with a modular design that makes the wash and rinse tanks completely separate. This means that tanks are regenerated individually and avoid the energy spill-over between the pre-wash zone and the wash zone.

The main benefits of this approach, according to Electrolux Professional managing director Andrew Jones, is in lower water usage (up to 30%) per cycle and a big (up to 75%) improvement in chemical usage. Machines also benefit from the fact that all doors are foamed "like a refrigerator" which provides additional rigidity and lower noise as well as energy-saving benefits.

Jones estimates that about 15-20% of Electrolux users in the UK now specify models with optional heat pump system. A further energy-saving feature is auto-start, which ensures that no water or energy is consumed during periods when the dishwasher is on standby.

Building assessments Building industry body the Building Research Establishment notes the benefits of heat pumps in its Environmental Assessment Method (BREEAM) for rating the environmental performance of both new and existing buildings. In one such assessment involving FCSI member Tricon Foodservice Consultants, a Meiko dishwasher fitted with a heat pump and CSS (Chemical Saving System) was estimated to achieve payback within 18-24 months. "And that's not taking into account the reduced water consumption," comments Gareth Sefton of Tricon. Another kitchen consultant, Garry Nokes of GWP, says that all major installations carried out by his company now include a wide range of energy-saving or reclaim equipment, with heat pumps now standard on mid-range and large projects.

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