HeatpumpMonitor.org heat pump database: minimum modulation tests

Hardware Heatpump
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The heat pump database tool now has the option to add minimum modulation test data. This should be a really useful set of data points alongside max output to aid with unit sizing:

See example on Vaillant 7kW page: HeatpumpMonitor.org

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and then min and max output averages listed on heat pump database list page:

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The heat pump properties section, below the tests, can now list min and max flow rate and maximum rated current as well:

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We’d very much welcome submissions of minimum modulation tests.

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A couple of interesting things this brings up so far:

  • The modulation range of the 10 kW Vaillant arotherm looks quite narrow, between 5.9 kW at minimum and ~9.6 kW at maximum. Yet this heat pump can perform very well even when the heat loss of the property is near the minimum modulation point. This suggests that well controlled degree-minute based cycling can compensate very well for a narrow modulation range.

  • The minimum modulation of the 12 kW arotherm is basically the same as the 10 kW - which is what we would expect given the understanding that the 10 is just a derated 12.

  • For Vaillant units the minimum flow rate x DT5 x 4150 J/K.kg gives a minimum output that matches observations quite well - but this does not hold for the 9kW Grant R290.

  • The minimum modulation on the Grant R290 9 kW unit is impressive, being fairly close to the minimum output of the 5 kW Vaillant and Ecodan.

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Hi @TrystanLea, how do we conduct the minimum modulation test? I’d like to take part.

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Hi @TrystanLea Definitely a useful set of data points! Can you tell us what the method is for both min and max and in particular how one can be certain that the min and max are truly being measured given that both may be limited by the downstream system or demand?

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Thanks @jamespa @jakeymd1 I will try and do a little screencast later to explain the process. Cheers!

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Tried to upload a test period, using the “share this view” in MyHeatPump, and got this error:

Error: Missing id parameter in URL

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Hi @TrystanLea

Would also like to take part in this data gathering exercise. Do you just need a link to a dashboard time period like below?

This is our (seemingly rare) 8kW Mitsubishi R290 Ecodan running at just under 2kW output for a few hours:

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Ready to send cosy 9 whenever you like.

It’s never not been minimum :joy:

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