Weather Compensation Control over HIUs
In Denmark is has become a statutory requirement for HIUs to include weather compensation.
We wouldn't suggest the UK follow such a strategy, as in some cases it works against efficiency, but in a number of cases the ability to weather compensate can result in lower return temperatures, so this article describes the methods we can currently deploy to enable this feature.
While such functionality is currently not built into our HIU controls, we do have a separate controller that plugs into the main controller to provide extended functionality, and can be installed inside the HIU casing. This controller, currently based on Linux technology, allows any HIU settings to be adjusted on the fly, including the limits on central heating supply temperatures as well as return temperature limits.
The controller takes a feed from an external temperature sensor and based on this temperature calculates the desired flow and return temperature settings, sending these at regular intervals to the HIU.
The system has the added advantage of providing a WiFi connection to the controller as well as a browser based user interface that allows commissioning engineers to setup the weather compensation curves to suit the property. Once setup this can be disabled or made accessible to the end user as a means to control and monitor the system.
Please refer to IHIU Control Systems for more information on the controller.