Pete Seddon, Head of Technical at Rinnai UK, explains the terms “hard and soft water” and expands on the long-term effects hard water has on DHW systems. Further attention is given to how system maintenance is provided to combat DHW system component fatigue – a result of untreated hard water.
Hard water areas can affect the internal components of DHW systems which gives less than an optimal performance and a reduction of system efficiency, as well as longevity. Hard water is an overlooked contributor towards a hot water system’s performance decline. This article will explain what hard water is, where hard water is located, the effects that hard water can have on a UK customers appliance, prevention and removal.
“Hard water” is water that contains a high concentration of dissolved minerals such as magnesium and calcium. Hard water forms once dissolved minerals are transported by flowing rainwater over certain rocks like chalk and limestone.
Hard water filters into the UK water supply once surface sources such as rivers, reservoirs and groundwater locations like aquifers collect. Rainwater accumulates that added mineral content.
Water companies then collect from these sources, chemically treat the water and then distribute through UK pipelines. However, minerals that are collected through this process remain present in drinking water, as there is no harm to human health.
The main areas around the UK that have access to a water supply that mostly contains “hard water” are predominately the south and south-east. Areas most affected are Thames Valley corridor, the Cotswolds, London and a large part of the Home Counties such as Kent, Sussex and Surrey due to the proliferation of chalk and limestone in the areas. Having said that there are also other areas dotted around the UK that can receive hard water. Most water suppliers will have postcode checkers on their websites which will allow you to find out what your water hardness is.
The effects of hard water upon a hot water system are long-term and can affect the performance and longevity of a DHW unit. One main characteristic of consistent use of hard water is a concentration of limescale inside hot water systems. Once limescale attaches itself to the internal components of a DHW unit, performance and efficiency is compromised by a build-up of limescale.
A buildup of limescale is formed by excess minerals within the water tank and connecting pipes of a DHW system. The limescale behaves as an insulator preventing the heat being transferred in to the water. As heat is absorbed by limescale the unit must work harder and longer to get the heat into the water resulting in higher energy costs and increased component fragility. This additional heat also exacerbates further build-up of limescale.
As a result of limescale on the internal metal components of a boiler, storage water heater or continuous flow water heater powered DHW system can begin to cause corrosion and erosion. Customers will have to confront leaks, an increase in maintenance costs, structural damage, operative failure and finally an early end to the product lifecycle.
Hard water impact and limescale infestation upon DHW systems and indoor plumbing pipes has been recognised as a major factor that requires problem solving. To prevent the forming of debilitating substances access to several technologies, chemical as well as natural solutions and techniques are readily available.
Water softeners are one potential route of limescale prevention but can also remove existing limescale build up albeit the removal will take time. Once a water softener is attached to in-coming water main a process called ‘ion exchange’ begins. Ion exchange replaces calcium and magnesium with sodium as well as potassium to soften the water content. Due to this technology physically softening the water, it is one of the best solutions however it does have its drawbacks so research should be carried out when choosing the most suitable treatment.
Limescale converters such as Aquabion are another option that reverses the effects of DHW systems that are reliant on hard water. A mechanism that resembles a pipe is inserted into the plumbing pipework and instantly starts to treat the hard water when drawn off. These devices could also start to disintegrate any formations of limescale within the system. Unlike a salt softener, limescale converters typically use a physical process to alter the structure of lime particles in the water. This process often involves using a device with a sacrificial anode, typically zinc. As water flows through the device, the lime particles are modified, becoming less likely to stick to surfaces and forming less hard deposits. This method can be preferred due to the minerals within the water being kept but also adding zinc into the water, all of which can add to health benefits.
Magnetic and electronic water conditioners are two further devices that supply a non-chemical solution to eliminating hard water limescale removal. The structure of minerals such as calcium and magnesium is altered using magnetic and electronic fields that disrupt usually associated behavioural patterns making limescale far less likely to attach itself to the internal elements of a hot water system.
If limescale is already present within an appliance or system, at a basic level a light acidic solution such as white vinegar can be used to breakdown limescale. White vinegar contains acidic properties that are ideal in dissolving nefarious hard water accumulations. Various chemical descaling solutions are also 
available – all acids such as hydrochloric, phosphoric, sulfamic, lactic and oxalic acid compounds are all well suited to destroying limescale. It is always preferable to use a suitable descaling solution rather than rely on the treatment options mentioned earlier because a limescale remover will be far more effective and take less time to remove any build up or deposits.
Rinnai aims to supply customers with all possible information that provides key knowledge enabling hot water and heating systems to perform at the optimum standard for a complete lifecycle. Rinnai will continue to seek out and share information that equips installers, specifiers, contractors and end-customers to arrive at a data-based choice of appliance and system based on practical, economic and technical criteria.
Please visit https://www.rinnai-uk.co.uk/ to find out more.
