It’s much easier to use this kind of mixing loop as a complete solution instead of having to design and install each component individually. The seamless interaction between the control unit and the pump is also a huge advantage.
"When it comes to heat contracting, it is crucial for us to be able to precisely monitor and constantly optimise the operation of our plants. That is why we started looking at innovative solutions for mixing loops early on," says Alexander Grafe, Technical Director at OVE. The medium-sized energy contracting company takes a comprehensive approach when it comes to supplying neighbourhoods with energy in an innovative and sustainable way, with already more than 450 properties nationwide.
OVE learned about MIXIT, the mixing loop solution by Grundfos, back in 2017. "The all-in-one solution with integrated pump control was exactly what we needed," recalls Alexander Grafe. "We talked to Grundfos at a trade fair and it wasn’t long before we had completed our first project with MIXIT." There are now more than 30 plants in operation. OVE is now using the latest MIXIT generation, launched by Grundfos in the spring of 2021.
Running the latest MIXIT generation
The first OVE project to use the new MIXIT generation is a housing estate in Bad Rothenfelde and OVE is using it as a reference property. The property features eight housing units completed in 2021 and another eight units are to follow in the second building phase in 2022. The supply technology has already been designed for all 16 housing units.
Heat is primarily generated by a gas-powered CHP unit. The de-coupled heat of 70°C-85°C is buffered using a phase-change memory to ensure optimal service life for the CHP unit. The units are supplied using a low temperature circuit, which is designed to keep the flow/return at 45°C/35°C all year. To do this, each unit has its own transfer station with an underfloor heating manifold and a combined electrical flow heater to support peak loads when heating domestic water.
Mixing loop adjusts the flow
A Grundfos MIXIT mixing loop ensures that the flow is lowered to the level of the supply circuit. To do this, part of the return flow from the supply network is added to the 60°C to 70°C flow. The return is at a temperature of about 25°C to 30°C and the required temperature for the supply circuit is around 40°C /45°C.
"Naturally, it is much easier to use this kind of mixing loop as a complete solution instead of having to design and install each component individually," says Alexander Grafe. "And the seamless interaction between the control unit and the pump is a huge advantage. The control unit controls the operation of the pump and also uses its sensors. All you have to do is set the parameters in the control unit and not each individual component. The bottom line is that the solution makes it extremely easy to precisely adapt the flow and to find the optimal Delta T (spread of flow and return temperature) for efficient operation."
Monitoring with the new cloud solution
The plant is monitored remotely from the control room at the company headquarters. To make this possible, the latest MIXIT generation is equipped with its own RJ45 input, allowing you to monitor the mixing loop using the Grundfos cloud solution, BuildingConnect. This platform is used to monitor, control and operate heating systems in smaller properties that do not have comprehensive control technology. While important functions can be used in the MIXIT standard version, the complete scope of functions requires a software upgrade for the control unit.
"The cloud solution is an important advanced development for mixing loops," says Alexander Grafe. "Now all we need is an active internet connection for access to all of the mixing loop's data points via the dashboard at the factory."
OVE plans not only to use the latest MIXIT technology in new plants, but also when modernizing old plants. "The all-in-one solution has proven itself to us in dozens of plants," affirms Alexander Grafe. "It reduces the cost of planning and installation, is easy to handle and gives us maximum control over the mixing loop operation. The cloud monitoring solution for the latest generation is a meaningful development and has made the concept even more attractive to operators looking to consistently optimise their plant."
The cloud solution is an important advanced development for mixing loops," says Alexander Grafe. "Now all we need is an active internet connection for access to all of the mixing loop's data points via the dashboard at the factory.
Komplettlösung für Mischkreise
Grundfos MIXIT ist ein Komplettlösung für Mischkreise mit flexiblen Angeboten und Funktionen, die für alle Anforderungen in Heiz- und Kühlsystemen ausgelegt sind. MIXIT verfügt über einen eingebauten Stellantrieb, Regler und Sensoren, was die Planung, Installation und den Betrieb von Mischerkreisen einfach und leicht macht.