A commercial dishwasher is a vital piece of equipment in any industrial or commercial kitchen. It is also probably the most expensive pieces of equipment in your kitchen, so you’ll need to pay special attention to regular maintenance, usage of proper chemicals and operating the machine correctly.
A lot of things can go wrong if the dish machine is not taken care of, but one of the most serious threats to your dishwasher and your business is hard water and its deposits – limescale.
Lime buildup is a common issue with any type of appliance that uses water. White, crusty deposits will form inside and around your dish machine and glasswasher, steam table, 3-compartment sink or any other equipment that is in contact with the water supply.
Besides giving your kitchen that old and dirty look, limescale can prevent your appliances from operating at satisfactory levels, and, eventually, break down. Moreover, lime buildup could cause mineral deposits or a white film to form on your dishware and glassware, which is something that your customers won’t rate positively.
Luckily for every owner of a commercial kitchen, there are chemicals designed to specifically combat and remove limescale called descalers or delimers, and there are special water softener systems, designed to cut the issue in its root.
10 Steps to Delime a Commercial Dishwasher [+Infographic]
Before you proceed with deliming a commercial dishwasher, make sure you get properly geared up. You’re going to need safety glasses, gloves and a mask to protect yourself from hot steam, dangerous acid burns and chemical fumes.
The best time to delime the dishwasher is either before your work day starts or after the working hours are over and the machine is empty.
Although the deliming procedure for high-temp and low-temp commercial dishwashers differs slightly we came up with an easy 10-Step Guide on How to Remove Limescale from High-temp and Low-temp Dishwashers.
Step #1: Everything Off
If you have a low-temperature dishwasher, you should start by turning off the chemical feed switch or removing the chemical feed lines from containers. You should be very careful when deliming a low-temp dishwasher, because some sanitizers include chlorine, iodine or quaternary ammonia that can form acid or noxious gas that can damage your dish machine or cause harm to your health.
In case you have a high-temperature dishwasher, start by turning off the detergent dispenser and removing the detergent, as it counteracts with the descaler. Next, turn off the dishwasher and the booster heater in case you have one.
Step #2: Water Out
The next step would be to drain any water from the dishwasher and to empty the wash tank(s). Even though your dishwasher has an automatic delime cycle, it’s always better to manually drain the water from the tank.
Step #3: Cleaning Time
Now you should inspect the rinse jets and lower and upper wash arms and clean them if necessary. Remove, clean and replace the drain screen, scrap trays, and open tips if needed.
Step #4: Water In
Now you should refill the machine with fresh water. In case you have a low-temp dishwasher, it’s best to turn on the machine and run it for one cycle to remove any possible traces of chlorine sanitizer. Refill it once again after the cycle is over.
Step #5: Descaler In
Next, add the descaling solution into the wash tank or to the drain port according to the manufacturer’s instructions.
Step #6: Cycle Time
Now it’s time to shut the door and run a cycle with the deliming agent. In case you have a high-temp dishwasher, turn on the machine, but do not turn on the heating elements.
Always check the manufacturer’s instructions for the recommended deliming time and it is important.
Step #7: Inspection Time
After the cycle is over, open the door and inspect the inside of the dishwasher (wash arms, rinse jets, etc.). If it’s not properly delimed, add more deliming solution and run another cycle while following the manufacturer’s instructions.
Step #8: Drain & Refill
When the dishwasher is free of scale buildup, drain the water from the wash tank and refill it with fresh water. In case you have a low-temp dishwasher, there will be an additional Step #9.
Step #9: Cycle Again (Low-temps Only)
In case you have a low-temp dishwasher, you’ll need to run the machine for another 10 minutes to remove the any possible deliming solution residue. After that, drain and refill the dish machine.
Step #10: Done & Ready
Now that the deliming process is over, it’s time to get the dishwasher ready for washing. In case you have a high-temp dishwasher, turn the dishwasher and the booster heater on, and turn on the detergent dispenser.
In case you have a low-temp dishwasher, turn the chemical feed switch back on or place the feed tubes back into containers, and get the chemical feed pumps ready.
Important: Always consult your chemical professional before your try deliming your commercial dishwasher yourself.
How NOT Deliming Your Commercial Dishwasher Can Hurt Your Business
The U.S. Environmental Protection Agency (EPA) hasn’t set a legal limit for water hardness, primarily because minerals that contribute to hardness do not have harmful effects on human health but can affect the aesthetic quality of water and can hurt your business.
Namely, the buildup of these minerals can cause damage to appliances, cause poor detergent performance and deliver poor cleaning results, which will become a nightmare for anyone who runs or works in a commercial kitchen. More details about the most serious ways hard water can interfere with the performance of your dish machine are presented below:
Affect the Detergent
Hard water can affect the amount of detergent that is necessary to deliver good cleaning results which can result in overusing it.
Also, some synthetic detergents can become less effective, because their active ingredient can become inactivated by hard water.
Cause Limescale Buildup
Heated hard water will cause limescale buildup, and limescale will cause inefficient operation, and eventually, dishwasher failure.
Scale can also clog pipes, cause water flow reduction, loss of water pressure and pipe corrosion. After the pipes get too clogged or corroded there will be no other solution then to change the whole pipe system.
Limescale shortens the life cycle of a water heater, because the it will have to work much harder to pass the limescale and heat the water. It will also reduce its efficiency and capability of reaching high temperatures.
Cause Visible Stains
Since hard water reduces the effectiveness of cleaners, the impurities don’t get easily rinsed away, so the film will remain. The white, red and black stains will be visible both on the inside of the dishwasher and on dishes, glasses and utensils.
Using more detergent to achieve satisfactory results will result in higher operating costs, as you’ll need to purchase more detergent more often.
Also, limescale will eventually cause dishwasher failure, so you’ll either be forced to constantly spend money on costly repairs, or to make a few capital investments into new dishwashers after they break down for good. Getting new piping system, water heaters, pumps and filters are just more things that can be added to the list of necessary but avoidable expenses.
Finally, since limescale prolongs the dishwasher’s operating time, the additional run-time will be very much visible on your electrical bills.
What is Hard Water?
All water sources can either be defined as “hard” or “soft“, and the difference is in the amount of naturally occurring minerals present in the water. Soft water can be defined as surface water that originates from lakes or rivers, that is free from most minerals that form insoluble deposits. On the other hand, water that is high in dissolved minerals, particularly calcium and magnesium, is considered as “hard”.
Soft water becomes hard by passing though ground and dissolving rocks and minerals. The longer the water travels through the ground that is rich in these minerals, the harder it becomes, because the mineral density also becomes higher. Therefore, water pumped from underground aquifers is harder than the water from rivers and lakes.
The level of water hardness is measured in grains per gallon (gpg), which defines how many grains of calcium carbonate is found in a gallon of water. There is a generally accepted division of water into four categories. The classification and respectable grains per gallon measures are presented below:
- Soft: 0 – 1.0
- Slightly Hard: 1.0 – 3.5
- Moderately Hard: 3.5 – 7.0
- Hard: 7.0 – 10.5
- Very Hard: >10.5
According to the US Geological Survey, more than 85% of the United States has hard water. The reason behind such a high number are the ancient sea beds that once covered most of the US territory. The sea beds disappeared, but they left behind a high concentration of limestone in areas that are today described as areas with “hard” and “very hard” water.
The hardest waters are found in Texas, New Mexico, Kansas, Arizona, Utah, southern Nevada, parts of Colorado and southern California. However, important to point out when mentioning these states is that certain cities might have significantly softer areas depending on the water source. Generally speaking, these are the six metro areas that are notorious for having the hardest water in US:
- Las Vegas (NV)
- San Antonio (TX)
- Phoenix (AZ)
- Indianapolis (IN)
- Minneapolis (MN)
On the other hand, only a small portion of population (15%) mainly located in New England, Gulf states, Pacific Northwest and some parts of Southeast are fortunate enough to have soft water running through their water systems.
If your business is on a municipal water system, then the water supplier can provide information on the level of water hardness, and in case of a private water supply, you can test the water hardness by using simple testing kits or strips or bringing water samples to a water testing laboratory. Most of those laboratories preform tests for free.
What is Limescale?
As mentioned previously, hard water is rich in dissolved mineral such as calcium, magnesium, iron and lime. Limescale is a white, chalky deposit of these minerals that hard water leaves behind after it evaporates from a surface. Precisely because water evaporates more quickly when exposed to heat, you’ll see limescale build up the quickest in kitchen appliances that use heated water, such as your commercial dishwasher.
How Does a Discaler Work?
To prevent limescale from forming, you’ll need to think about introducing a water softener system. However, in case you already have a limescale buildup, you’ll need to delime your dishwasher. Although there are some natural ways to remove limescale, those methods are more suitable for residential dishwashers.
Since limescale and detergent scum are difficult and time consuming to remove in a commercial kitchen environment, you won’t get by without the chemicals that have high limescale removal abilities. Here you’re going to use a chemical substance that goes around by many names – delimer, descaler, scale remover or lime remover.
Limescale remover consists of low foam surfactants and acids, and acids are the main ingredient that makes a descaling agent powerful against scale. Here’s a little bit of 8th grade science to explain the process.
On one side, we have limescale carbonate minerals that are alkaline (or basic), and on the other we have a delimer that is an acidic solution. The reaction between an acid and base is called “neutralization reaction”, because the acid will dissolve the minerals and leave you with a nice, shiny and limescale-free surface.
There are three types of acids used most often in commercial descalers and they range from least aggressive to most aggressive:
- Lactic acid based delimers (aka green delimer) – least aggressive;
- Phosphoric acid based delimers – medium aggressive;
- Hydrochloric acid based delimers – very aggressive.
As for the surfactants, their main purpose is to remove other limescale components, such as oils, rust, silica and other contaminants that can be found in the water system.
How to Choose a Descaler?
There are two main factors to take into consideration when choosing a descaler: water hardness and the surface the descaler is going to be used on.
As explained, water hardness is determined by the geographical location, and the type and location of the water source of your area. After you determine the exact type of water in your area, you’ll be able to choose the right delimer.
The hardest waters will require the most aggressive, hydrochloric acid-based scale removers that are effective in removing red minerals, such as iron and rust, while moderately hard water will require some less aggressive descalers.
Note: Know your chemicals. Most aggressive delimers are not suitable for manual use or spray applications, as dangerous fumes could spread all over the kitchen.
As for the surface you plan to use your descaler on, you’ll need to make sure that the deliming agent is not going to damage it. For example, interior compartments of industrial dish- and glasswashers, such as gaskets and seals, can be sensitive to hydrochloric acid as are all softer metals. The strongest acids can be mixed with inhibitors to reduce the damage to certain metal components, but they don’t work well on all metal surfaces and many are hazardous.
On the other side, the level of water hardness might be really high and require aggressive descaling chemicals, so the best would be to consult professionals regarding the best possible long-term solution.