Using ultrasonic flow meters

I have been tasked with finding a solution for metering hot water heat pumps for commercial-scale DHW here in New Zealand.

Some of these will be for metering existing systems in order to get usage data prior to replacement.

Then most will be for ongoing monitoring once the funded work is done.

The Emon HP looks to be a solid option, but I was wondering how easy the integration of an ultrasonic flow meter would be. The units we are looking at have a 4-20mA output. An RS485 serial, and what is called oct pulse.

This allows for an affordable flow meter and allows for surface mounting on existing pipework. I have used Sontex and Kamstrup plenty before on RHI installations and the like.

We need 2 heat meters per install, as we need the total DHW delivered, but there is a ring main (some as big as 42mm pipe and with a standing loss in the region of 6kW) that I need to deduct from the overall energy to allow a DHW figure to be calculated.

Any pointers would be much appreciated.

RS485 would probably be the easiest to integrate with, the emonHP does not have a ADC converter so interfacing with analogue signals would require additional hardware.

Most heat meters we interface with use MBUS protocol: emonHub Interfacers — OpenEnergyMonitor 0.0.1 documentation