Filling a Heating System with Demineralised Water

Following on from my previous post I will now cover filling heating systems with demineralised water which is a requirement of VDI2035, this is a good and cost effective option for the domestic market here in the UK

The product I use controls the pH during filling to 8.5, this is ideal for heating systems, these units also remove salts, lime and TDS via the resin cartridge, so create water with low conductivity no scale deposits and correct pH for a heating system, this is essential in preventing corossion, water with low conductivity will restrict the path of corrosion, even in the presence of oxygen, although we don't want oxygen in our systems, it just shows that even with an oxygen ingress, the system can still be protected with the correct water, although I would always suggest any oxygen ingress needs to be found and eliminated

The unit I currently use is the Elysator Purotap Leader, these are great units, as an installer i take this from site to site with me and fill the system through the cartridge, as per the image at the header of this blog, the display on the Leader shows me the conductivity of the incoming water (figure on the right) and on the left it shows the conductivity of the water going into the heating system after it has passed through the cartridge, it also shows me the volume of water that has passed through the unit, so I know the exact fill volume, each cartridge will fill multiple systems, but how long the cartridge lasts will depend on the hardness of the water in the area you are in, obviously the higher the hardness of the water the sooner the cartridge will be depleted, but down here in the South East where we have very hard water, I get multiple fills, so very cost effective, but I have confidence knowing that the fill water of my systems has a pH of 8.5 and low conductivity, unlike with chucking in chemicals, I have no idea what the pH is and chemicals actually increase the conductivity of the water, I have been using these methods now for over 7 years, I know they work.

Using the Leader is simple, just connect the mains water supply to the inlet connection on the Leader and then connect the outlet of the Leader to the heating system connection, so basically it's just putting the leader in the line of the quick fill of a heating system, so rather than the raw mains been put straight into the system, the mains water goes via the Leader and the water is treated

Below is a image showing the Leader is connected for filling a system

Once the system has been filled, then the question often gets asked what about future topping up of the system, well this is covered by fitting a purotap micro, a small unit that gets fitted to the wall and connects to the quick fill, the cartridge in this unit ensures any top up water is treated so the water is also conditioned, keeping the water in the system at its optimum, but like anything the cartridge in the Micro will deplete, so during boiler service the condition needs to be checked and replaced if necessary, it is easy to identify when the cartridge is spent as it changes colour from Blue to a pale grey/beige colour

Below is an image of the Purotap Micro, which comes with a wall bracket for easy installation

 In my opinion this method of conditioning the heating system water is by far a better method, you are providing chemical free water which will prevent corrosion, I will continue to use this method to fill my systems and I actually see this growing amongst installers as they face water quality issues with longer boiler warranties, this method is used in Germany, Austria and Switzerland, they use the same makes as boilers as the UK, same pipe work and same heat emitters radiators or UFH, so something which i have heard mentioned before where some say this method is not suited to the UK is utter nonsense

I hope this helps explain how to use a demineralisation unit to fill a heating system and the benefits it provides in corrosion prevention, the next blog will be on the Elysator SorbOx