Glasswasher and dishwasher guide for purchasers and installers

Commercial dishwashers and glasswashers - guide for purchasers and installers

Catering Appliance Superstore have produced general guidance for the purchase of commercial dishwashers and commercial glasswashers in our separate buyers guides, but we have also produced an additional plain English guidance sheet here to help navigate the intricacies of commercial warewasher installation. These are a few essential considerations we believe prospective buyers should be aware of before they begin to look at "nice to have" warewasher features like energy and water efficiency, rinse boost pumps or extended warranties.

The purchase and installation of a commercial glasswasher or dishwasher is a slightly more complex prospect than the purchase of their domestic equivalents. Regardless of which model you ultimately choose after reviewing the buying guide, there are a few things you absolutely need to understand and get right. In this guide we will cover the following:

  1. Break tanks and WRAS legal requirements
  2. Servicing valves
  3. Water pressure
  4. Drain pumps
  5. Requirement for a water softener
  6. Type of water softener
  7. Electricity supply
  8. Hot vs cold water supplies


To make things as simple as possible, we have added customer filters to our glasswasher and dishwasher pages to help you narrow your range of choices in line with the following considerations.


1.) Break tanks and WRAS legal requirements

The 2005 Water Regulations Advisory Scheme (WRAS) states that storage cisterns or tanks connected to the public water supply must protect that water supply from contamination from backflow - a commercial dishwasher or glasswasher counts as a cistern (cistern is just the technical term for any container that holds water fed by an inlet).

Unless you are on a private water supply or outside the UK (where other regulations may apply), your installer will need to ensure a dishwasher incorporates a visible and unobstructed vertical air break between the inlet pipe and the tank water level. The exact specification of the break tank is determined by a five point contamination rating, from clean water at one end to...quite dirty water at the other. Commercial dishwashers are somewhere in the middle.

Theoretically a catering business can commission a plumber to install an air break tank system external to a commercial dishwasher that is not supplied with a built in system, but the installer would have to be a specialist and the total cost would likely be prohibitive. Install a commercial warewasher without a break tank on a public water supply and you risk prosecution.

All of this means that our strongest advice is to purchase a dishwasher with a built in break tank of type A for fluid category 5 (the strongest protection available), of which several are available at Catering Appliance Superstore, always clearly marked in each product description.


2.) Servicing valves

WRAS guidance also states that your plumber must include a servicing valve on the water inlet as close to the commercial dishwasher or glasswasher as possible, to be able to switch off the water to that machine to facilitate maintenance.


3.) Water pressure

Commercial dishwashers and glasswashers operate best in a particular range of water pressure, generally 2 to 4 bar (or 28 to 56 psi). Low pressure can result in lethargic rinser spin (rinser arms are usually powered by the water pressure through the unit), amongst other performance problems. High pressure can cause damage to the machine over time.

There are various dubious DIY schemes for testing water pressure, such as attaching a hose to the mains and raising the end vertically to see how high the water can be pumped, but if you suspect you have high or low pressure you're best advised to book a plumber in to check it or buy your own mains water pressure tester (which are not very expensive).

An internal fitted or external booster pump will neatly deal with low water pressure problems, and high water pressure can be addressed by a restrictor valve fitted by a qualified plumber.


The product descriptions for Catering Appliance Superstore's range of commercial warewashers clearly state the water pressure requirements so you can check against any water pressure measurements you take, and whether the device includes a rinse booster pump or whether one can be added as an optional extra.


4.) Drain pumps

Drain pumps are required when waste drains are situated higher than the warewasher outlet. Mounting a commercial dishwasher or glasswasher on a surface or stand can avoid the need for a pump, but if this is not possible and your commercial dishwasher waste water needs to travel uphill to escape then a pump will be required.

The product descriptions for Catering Appliance Superstore's range of commercial warewashers clearly state the height of the machine drain from the floor so you can quickly check, and we list any options for built in drain pumps where these are offered by the manufacturer for that model.


5.) Requirement for a water softener

In hard water areas, it is strongly recommended that a water softener is used in conjunction with your commercial dishwasher or glasswasher to avoid a build up of limescale that will block jets and render the machine ineffective. Even in areas where limescale build up is less noticeable, water softeners are a good idea if you want to extend the working life of your dishwasher, or at least reduce the need for regular disassembly and deep cleaning of rotary jets.

Minerals in hard water can also reduce the effectiveness of soaps and detergents by combining with them before they have had a chance to function on the items being washed, in the process forming soapy deposits that can themselves leave spots and stains on dishes, glasses and cutlery.

You can consult the website of your local water supplier for a general reading of water hardness, or you can purchase a water hardness test kit from a plumbing supplies or general DIY store for a more specific reading. Many are available online for just a few pounds and can be delivered next day. They work by dropping small tablets one at a time into a measured pot of your water - when the water changes colour, check the number of tablets you have used against the chart provided to determine water hardness. You should get a measurement expressed as ppm (parts per million).

If the result is less than 100ppm, you don't need a water softener. If the result is between 100ppm and 300ppm, we strongly recommend a water softening solution of some kind, and for water hardness above 300ppm a high spec water softening system becomes essential for the warewasher to function for any length of time, and results may still be negatively affected. If you are worried about especially high water hardness measurements at your commercial catering operation, please get in touch with us and we can investigate options for you.


6.) Type of water softener

Water softeners work by swapping the minerals (calcium and magnesium) in hard water for sodium (salt) in a process called ion exchange. All water softeners need to kept topped up with salt, or "regenerated".

The water softener is filled with small beads that have a negative charge. Calcium and magnesium ions have a positive charge, so they stick to the beads as the hard water enters your washer. Sodium ions are also positive, and when brine solution is forced through a tank that has beads coated in calcium and magnesium, the hard water ions are displaced and can be flushed away - this process is called regeneration and needs to occur at regular intervals or your water softener will stop working.

Once you've established whether you need a water softener at all, you need to decide what model to opt for. This decision will be based on the type of water supply (hot or cold water) to your commercial dishwasher or glasswasher, the type of warewasher (frontloading or passthrough system) and how heavily you will be using your warewasher, which will determine the capacity of water softener you need to keep up with the quantity of hard water being used.

The performance of the water softener will depend on the hardness of the water. For example, at 300ppm, the DC range of warewasher water softeners achieves 125 litres (or 40 wash cycles) for frontloading machines and 250 lites (or 80 wash cycles) for passthrough machines, before the water softener has to be regenerated.

Manually regenerating water softeners are available, but for ease of convenience and the comfort of knowing your wash water is being consistently softened, we suggest models with integral, automated water softening systems if possible.

Finally, you will need to choose a water softener for either a cold water fed warewasher, or a hot water fed machine. Cold water fed machines can have internal water softeners, but hot water fed machines generally cannot, and there are other differences which mean you need to be clear on how your commercial dishwasher or glasswasher will be plumber in before you purchase the water softener.

Catering Appliance Superstore makes it easy to choose the right water softener for your dishwasher - each product has drop down options that list any compatible water softeners and their essential features, including whether they are suitable for hot water or cold water fed washer installations.


7.) Electricity supply

Catering Appliance Superstore provides a full, plain English guide to electricity supply for commercial appliances to ensure our customers can make informed purchases. We recommend you read this before purchasing a commercial dishwasher, but the main points are summarised here.

Check whether the commercial warewasher is supplied with a fused plug or needs to be hardwired to the circuit. Hardwired connections are more efficient and less prone to wear, but obviously once the dishwasher or washing machine is connected up it will be difficult to move it. You generally have the same restraint with the water supply too, so you need to choose your installation location carefully and stick to it.

Check the Amp rating of the machine against the spare capacity of the circuit you want to install it on. Check whether you are on single phase supply or three phase supply - our range of dishwashers and glasswashers are sold as suitable for 230 or 240 Volt single phase supply, but we can provide variations of some machines that are suitable for three phase supply, such as the hardwired, high powered D.C SXD50.


8.) Hot vs cold water supplies

You can connect most of the dishwashers we sell up to hot or cold water supplies, but please check the product information listed. Cold water fed machines have a maximum input temperature of 30 degrees C, hot water fed warewashers have a maximum input temperature of 60 degrees C.

If you have access to relatively cheap hot water, it could be more cost effective to opt for a hot water feed. For example, if you have a highly efficient water boiler, or if you use solar power or other self sufficient measures like a biomass boiler to heat some of the water to your property, we would recommend fitting your dishwasher to the hot water supply rather than relying on a built in electric heating element within the machine itself.

Remember, if you want to connect to a hot water supply and you're using a water softener, you need to choose the right water softening solution and the water temperature should not exceed 60 degrees C.

By Philip Wearmouth | Catering Appliance Superstore