Connection of the drinking water supply to the heating system Protecting drinking water when topping up the heating system using the GOETZE 9660 Type BA backflow preventer
Heating system top-up as a safety-critical interface
In residential and commercial buildings, heating systems must be topped up with water on a regular basis. To do this, the heating system is connected to the drinking water supply via a filling pipe. This connection is a safety concern, as heating water does not meet drinking water standards.
Heating water may contain corrosion products, deposits or chemical additives. If pressure fluctuations occur in the drinking water supply, there is a risk that heating water will flow back into the drinking water system without a suitable safety device.
GOETZE is your partner for safety here too.
For precisely this application, GOETZE offers a standard-compliant solution in the form of the 9660 Type BA mini backflow preventer made from lead-free brass. The backflow preventer ensures that drinking water and heating water remain securely separated from one another even under fluctuating pressure conditions, and that the drinking water system is reliably protected.
Pressure differentials as a trigger for backflow Why pressure fluctuations pose a risk to drinking water hygiene
Fluctuations in pressure within the drinking water network can be caused, for example, by burst pipes, maintenance work or high simultaneous water consumption. If the pressure on the drinking water side drops below the pressure of the connected heating system, backflow or backpressure may occur.
In such situations, there is an aseptic risk if a backflow preventer is not in place. To protect drinking water, a safety device is therefore required that functions reliably even when pressure conditions are abnormal.
Clear guidelines from standards and regulations
The DIN EN 1717 standard regulates the protection of drinking water systems against contamination caused by backflow. Under this standard, heating water is classified as fluid category 4, as it may contain substances that are hazardous to health.
A type BA backflow preventer is intended for use in this category. Thanks to its design, it ensures safety in the hydraulic separation between drinking water and non-potable water.
Use of the lead-free GOETZE backflow preventer, type BA
In this application example, the GOETZE 9660 Type BA backflow preventer is installed in the heating supply line between the drinking water pipe and the heating system. It provides protection in accordance with DIN EN 1717.
Thanks to its compact design, the backflow preventer is particularly suitable for confined installation spaces, such as those often found in boiler rooms, plant rooms or during renovation projects.
The three-zone printing principle as the technical basis Design of the backflow preventer with defined pressure zones
The GOETZE Mini Backflow Preventer Type BA operates with three clearly separated pressure zones.
- The inlet pressure zone p1 is located on the drinking water side and is fitted with an inlet non-return valve.
- The intermediate pressure zone p2 contains the drain valve and serves as a safety zone.
- The outlet pressure zone p3 is located on the heating system side and is fitted with an outlet non-return valve.
The pressure ratio is specified in the design as p1 > p2 > p3. This defined pressure gradient forms the basis for the protective function of the backflow preventer.
How it works during the heating system top-up
During the heating system top-up, drinking water flows in a controlled manner from the mains water supply to the heating system. The check valves open in response to the pressure, whilst the drain valve remains closed.
The low pressure drop of the GOETZE Mini backflow preventer facilitates efficient refilling and contributes to cost-effective system operation.
Behaviour of the backflow preventer in the event of a pressure drop
If the pressure in the drinking water circuit falls below that of the heating system, the check valves react automatically and close. At the same time, the relief valve opens the medium-pressure zone to the atmosphere.
The slight dripping from the drain valve that occurs is minimal and indicates that the backflow preventer is actively protecting the system and reliably preventing heating water from flowing back into the drinking water supply.
DO YOU HAVE ANY QUESTIONS? Looking forward to helping you!
Pascal Joos
Business Development Manager
‘In the Water Applications Worldwide division, I am responsible for the Water & Building business unit. With my background as an industrial engineer and my experience at Goetze, I develop concepts that strengthen existing customer relationships and open up new markets.’
Phone: +497141 48894676