Modulation - what is your experience?

matt_drummer

None of them tell you, they don't even tell you what size their heat pump really is, you have to work it out yourself. It really is best to look at real world MID monitored heat pumps, it will tell you pretty much all you need to know.

Why are you asking?

Are you looking for a replacement?

NedS

michaels said:

NedS said:

The Heat Pump Monitor site has a table of minimum real world outputs for various heat pumps which you may find useful:

https://community.openenergymonitor.org/t/heatpumpmonitor-org-heat-pump-database-minimum-modulation-tests/29132

Hardly any manufacturers publish modulation data. The general rule of thumb is that most heat pumps will modulate down to around 25% of rated output. The reason they are limited to around 25% is that efficiency falls off a cliff if they modulate down much lower. They could modulate down to 10%, but you'd actually use more electricity for less heat output, hence each manufacturer will limit how low the compressor can modulate in an attempt to keep it within an acceptable operating window.

Be aware that 25% rule of thumb applies to the compressor hardware, not the headline sticker output of the unit. For example, my 12kW Samsung unit is really a 16kW unit that has been software limited to 12kW, so it's minimum output is 25% of 16kW (e.g, around 4kW), not 25% of 12kW (e.g, 3kW, which would have been much better for me).

Useful. I wonder if the max and min relate to output kw or input kw?

In heatpumpmonitor.org's heatpump table they are output figures (kW). Data is somewhat limited atm but they are adding more real world data all the time. 

Netexporter

That's interesting. Looks like I've got a bit of work to do to get my Gen 6 Samsung down in the 300s.

I wonder if the figure includes the circulating pump? If I knock that off I'd be getting closer.