@SarahH Interesting thought. Now that you have a room stat that allows you fine control of hysteresis, I’d be interested to see the outcome of such an experiment.
However, I recall a slide at the end of one of John Cantor’s YouTube videos (@20:30min):
that indicates maximum efficiency at around 40% compressor speed, with a sharp roll off below 25-30% (hence why OEMs only allow their units to modulate down so far), and a more gentle roll off in efficiency above 50% (relevant to this discussion). To this end, I’m currently running with #5051 set to USE to limit compressor speed to 50% max, which hopefully helps with DHW runs but does little to help me with continuous heating runs although may benefit shorter runs (oversized heat pump, so I’m able to do this in anything other than the very coldest of days). Whether this is correct for all compressors, I do not know, but it kind of made sense to me based on the analogy that my car is most efficient with running at ~50mph even though it is capable of running at 0-100mph.
I have previously tried to minimise the number of cycles by extending the off time as long as comfortably possible. I also figured that the heat pump is going to be more efficient reheating water that has cooled to 20C back to 32C LWT than reheating from 25C back to 32C LWT (more time working at lower temperatures). But maybe your suggestion of shorter cycles to spend more time operating in the 40-50% range may be more efficient.
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with the Parameter changes, it feel like a weight is lifted off my shoulders already, and just to achieve a more benign steady state with this Samsung ASHP is fantastic.
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