Getting sensible flow rate as litres/min from the heatpump_flow feed

Getting Started
1

Hi,

I’m trying to generate a Machine Learning training set from the system information that’s publicly available.

I’m pulling down data electricity input, flow temp, flow rate and outside temp using this URL.

https://heatpumpmonitor.org/timeseries/data?id={id}&start=01-06-2023&end=01-06-2024&feeds=heatpump_elec,heatpump_outsideT,heatpump_flowrate,heatpump_flowT&interval=3600&average=1&timeformat=notime

When I format this into a CSV, I’ve noticed that the flow rate values are enormous

Here are a few examples.

540.6100546095106
538.4602754380968
70.95514704386393
21.969012451171874
56.996384684244795
537.2835748460558
537.8868751525879
548.0047322591146

I appreciate this value is m³/h, but it’s still insane.

What am I doing wrong? Could this be related to interval?

2

Hello @tomasmcguinness

The units for flow rate are not consistent for all systems, most are L/min, mine is m3/hr, I wonder if that one is L/hour?

You should be able to access the units via e.g: https://heatpumpmonitor.org/timeseries/available?id=2

3

Ah. So that endpoint will tell me the feeds (and units) available for each system if I change the ID?

4

I tried that and it’s making sense.

Some of the flowrate feeds don’t have a unit property available.

What is the default unit for flow rate? Is it litres/sec?

5

Litres/min is typical I believe, and should be in the range 5-30ish L/min. If you’re really stuck, perhaps as a sanity check:

heat_output = flowrate (L/s) x 4150 J/K.kg x (Flow temp - return temp)
flowrate = heat_output / (4150xDT)

We should automate a script on the server to apply these units consistently!

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6

Had better success with that. You’re right about the units. The values come back where sometimes in l/h, m3/h or l/m. I’ve excluded any feeds without a unit value to save me from guessing.

I’ve also used the start_time and end_time to get better timeseries data.

The predicted value is better, but still off. I’m certainly no data scientist, but we all start somewhere :slight_smile:

I’ve written this up if you fancy reading more: Mass Flow Rate, not Room Temp – tweaking my Heat Pump Maching Learning Model – @tomasmcguinness

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