Water quality guidelines for central heating systems with Vaillant or Glowworm boilers installed
This blog post contains information regarding the recommended pH levels for Vaillant and Glowworm boilers, depending on the material their heat exchangers are made from.
This information is relevant to any central heating system with any boiler installed that has a heat exchanger made from stainless steel or aluminium.
At the bottom of this post there is a link to a Vaillant PDF document regarding Galvanic Corrosion on Vaillant boilers.
There is also a link to an in depth detailed PDF document called Water quality instructions for central heating systems.
General pH guidelines for central heating systems
The general recommended pH level for central heating systems generally falls between 7.0 and 9.0, but this can vary depending on the materials used in the heat exchanger.
Systems with aluminium components often require a slightly lower pH, typically between 8.2 to 8.5, while copper can be affected by pH levels above 9.5.
Stainless steel is generally more tolerant, with a pH range of 7.0 to 9.5
Galvanic Corrosion
Heating systems containing mixed metals are most at risk from galvanic corrosion.
Modern Vaillant boilers contain various different metals including;
copper, stainless steel, composites, brass and aluminium, depending on the model.
Most heating systems also contain mild steel (radiators) along with copper, brass and plastic piping.
What is Galvanic Corrosion?
Galvanic corrosion is an electrochemical process causing excessive corrosion in one or two metals in contact with one another in the presence of an electrolyte.
In a central heating system, this electrolyte is the system water itself.
How does Galvanic Corrosion occur?
Metals are graded on the noble scale.
Metals which are next to one another on the noble scale have the least difference in electric potential, so will not react together, however metals which are further apart will react more favourably with one another.
When this occurs, the most noble metal will become the cathode, and the least noble metal will become the anode.
This causes the anode to suffer heavy corrosion as part of the reaction.
Modern central heating systems
Modern central heating systems are complex.
The systems comprise a lot of different components and materials: steel, copper, brass, aluminium, stainless steel and cast iron, as well as all kinds of plastic and rubber.
It is important for all of the components and materials within the central heating system, that the water quality is managed and corrosion is prevented.
Good quality, clean water in the installation ensures optimum heat transfer to all applicable parts of the system.
It also helps to maximise efficiency and reduce energy consumption, and lengthens the service life of the components in the installation.
The latest high performance boiler models feature increasingly compact designs.
As a result, heat exchangers are delivering a greater flow of heat over a smaller heat transfer area.
The presence of hard water in a central heating system can cause limescale deposits to form in hot areas.
Most notably, this happens in heat exchangers in central heating boilers, regardless of the material from which them heat exchangers are made.
In some cases it may be necessary to decalcify/soften the water in the central heating system.
The decalcification method and the scope have a considerable impact on the corrosive effect of the water in the CH system.
Recommended PH levels for Vaillant boilers with stainless steel heat exchangers
For central heating systems with Vaillant and Glowworm boilers with stainless steel heat exchangers, the recommended pH level typically ranges from 8.0 and 8.5.
This range helps prevent corrosion of the boiler heat exchanger and ensures the system operates efficiently.
It’s crucial to maintain this pH level to avoid potential issues like scaling or corrosion.
Recommended PH levels for Vaillant boilers with Aluminium heat exchangers
For central heating systems with Vaillant and Glowworm boilers with aluminium heat exchangers, the recommended pH range for the water is generally between 6.5 and 8.5.
This range helps prevent corrosion of the boiler heat exchanger and ensures the system operates efficiently.
Maintaining the pH within this range is crucial to prevent corrosion of the aluminium, as it can be susceptible to corrosion at higher pH levels.
Essential information heating engineers should know
Below is a link to an important document called water quality instructions for central heating systems, which I recommend every heating engineer should read at some point.
This document includes guidelines and advice for the quality of the water in a central heating system, to ensure that the heat exchanger and other system components continue to function reliably and continuously.
Failure to follow the instructions may result in the warranty for a central heating boiler to be invalidated.
Technically the user or manager of the system is always responsible for ensuring that the water in the system is of high quality.
However this responsibility ultimately lies in the hands of the installer and whoever maintains the boiler and central heating system afterwards.
There is also a link to a document regarding galvanic corrosion.
Downloads
Vaillant galvanic corrosion leaflet PDF
Water quality instructions for central heating systems PDF
The benefits of using us to repair your Vaillant boiler
Local engineers on time
You know that when you call us you’re going to get a local, experienced, Gas Safe registered heating engineer with over a decades worth of experience working on Vaillant ecoTEC boilers, who will turn up if they have promised to do so.
12 Month guarantee
To provide you with the best possible service and peace of mind, we always provide a minimum 12 month guarantee on any parts fitted to your Vaillant boiler or central heating system
What our customers say about us…
I’ve used Richard to service my boiler for several years. He is extremely professional, knowledgeable and thorough. The first time he looked at my boiler he fixed a problem that several other engineers had failed to fix, and even refunded me when a part he had bought turned out not to be needed. Real integrity and a desire to do the best for his customers. I don’t think you’ll find anyone better.
Tim
I can’t recommend Richard highly enough. He came to fix our boiler at short notice, provided a comprehensive service and has given it a new lease of life. He had all the parts required so no delays in waiting for parts. He is extremely knowledgable and competent and clearly passionate about what he does. Thank you!
Gareth
Need an urgent Vaillant boiler repair in Rotherham?
Thanks to our extensive professional experience working on Vaillant ecoTEC boilers, and all the Vaillant boiler spares we carry, most broken Vaillant boilers are repaired with just one visit – getting your Vaillant boiler up and running as soon as possible.
Aside from offering a great price on boiler repairs, we also offer a 12 month guarantee on all parts fitted to your Vaillant boiler or central heating system.
Call today
07507712787
Recent Blog Posts
Vaillant myVAILLANT, sensoROOM and VR controller installation
View Article
Central heating water pH guidelines for Vaillant boilers
View Article
