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“Midi-Fill” Digital and Dose and Fill Case Study

Heating system innovations requiring no annual commissioning.

Arrow Valves developed the “Autofill” Pressurisation Unit as device that utilises mains water pressure in order to top up a sealed heating system, it incorporates and RPZ valve for backflow prevention. Although a popular unit, the RPZ valves require annual commissioning and therefore this additional cost can put potential buyers off. To overcome this Arrow Valves developed the “Midi-Fill” a Fluid Category 5 Pressurisation Unit that utilised a pump to generate pressure and did not require annual commissioning. It featured innovations that would prevent the pump from seizing up (a common fault with pumped systems) and a low-pressure sensor that warned of imminent failure of the pressurisation unit that would prevent the heating system from working when required.

At this time, we were invited to a training day from one of our suppliers (OEM) regarding a logic controller (Crouzet Millenium). A device that has a set of inputs, and outputs and is programmable via a computer interface, our Technical Director saw the benefits of said device and realised that the MFD could be enhanced with many end user functions. He also thought that the controllers could be used to develop a new concept where by the pressurisation unit would have the ability to measure the water used to top up the system, and based on pre-determined values would inject the required amount of chemical inhibiter, thus insuring that the concentrate level was always correct and protecting the system. This would be an innovation for the heating system as there is nothing like it on the market.

The units were put into development, and the advantages of the programmable controllers became more apparent as experience was gained as the project progressed. Our experience in the field has given us a unique insight as to how systems work and we could tailor the functions of the controller to reflect this. The “Midi-Fill” became the MFD, a unit that is so advanced it will monitor itself throughout the year, and during periods where heating is not required and a conventional pressurisation unit could potentially seize up, the MFD will measure its ability to produce pressure and if it were to detect a problem warn via the BMS panel. This would alert the maintenance team long before heating is required.

The Dose and Fill unit is essentially 2 units combined, it uses the MFD controls, for the pressurisation part and then has an additional controller to monitor the dosing side of the unit. The unit saves space, labour and takes the guesswork out of dosing the system.  

The development of these units has given Arrow an understanding into the functionality of the millenium (logic) controllers and how they can be applied to future products in the Arrow range.