Table of Contents
WikiSIS is the place where you can find all the answers to preventing the Sick Installation Syndrome (SIS).
Topics that affect SIS:
Introduction to WikiSIS
Many heating and cooling systems suffer from chronic problems. No matter whether they are small domestic systems or large commercial systems in hospitals or airports. The most common problems are known to all installers and maintenance companies, like sticking thermostatic radiator valves, frequent pump failures, blocked valves, noisy boilers, leaks, increasing energy consumption, system pressure dropping and requiring frequent top ups, black sludge and reddish brown water. Often these problems are seen as normal and unavoidable. Left untreated they will inevitably lead to component and and in the end even complete system failure. Power flushing and chemical treatment often fail to cure the problem and can even make the problem worse.
Don't just accept it!
It is possible to have systems that don`t suffer frequent breakdowns,that work efficiently and reliable over it's entire life. This Wiki is dedicate to eradicating sick systems. The result will be a permanently healthy and efficient installations.
The Sick Installation Syndrome
Sick Installation Syndrome is a collective term given to water-related problems in heating and cooling systems. The common symptoms of SIS are well known such as reddish, brown or black water, seized pumps, noisy or failed boilers, leaks, stuck valves, cold radiators, gurgling noises and clogged pipes. Systems showing these symptoms suffer premature component failures, higher maintenance costs and greatly reduced efficiency.
The aim of this WikiSIS is to explain why systems suffer from SIS and how the root causes can be identified and rectified. The good news is that SIS can easily be prevented from attacking your heating or cooling system in the first place without any additional equipment or chemicals and at no or little extra cost.
What Causes The Sick Installation Syndrome?
All the symptoms described above can be linked to one thing: They are caused by corrosion and its associated effects. Corrosion comes in many forms and can be a very complex subject. In heating and cooling systems, the most common form by far is Uniform Corrosion, also called General Corrosion.
Why do Systems Corrode?
All systems containing metals such as steel, brass, copper etc. corrode. Low levels of corrosion in itself is not a problem. It only becomes a problem if there is continued or accelerated corrosion. There are a number of possible causes for continued or accelerated corrosion rates. Uniform corrosion, which is by far the most common form in non-chemically treated heating systems, can only occur in the presence of oxygen. Simplified it can be said that the more oxygen is present in the system the higher the rate of corrosion.
Without oxygen, corrosion will stop. Therefore it is vital to prevent oxygen from entering the system.
There are a number of ways oxygen can enter a system:
- Dissolved in the initial fill or topping up water
- Trapped as air in the system after filling
- Diffusion through non-diffusion tight materials such as plastics and rubbers
- Low system pressure allowing air to be sucked in at high level
The amount of oxygen that enters the system and therefore the corrosion that is caused by these mechanisms varies greatly.
Research has shown that incorrect pressure control leading to air being sucked into the system at high level leads by far to the most corrosion. How this happens is not immediately obvious and therefore often not identified as a cause of the corrosion.
In the majority of closed heating and cooling installations, an expansion vessel controls the pressure.
It therefore follows that
the expansion vessel plays a vital role in the fight against corrosion and the Sick Installation Syndrome.
