PhilT

could be - the specs say it has "low temperature protection", but that's a very short warming time and it happens every single discharge irrespective of temperature

At around 02:40, with consumption (orange) continuing at a background level, there is an unscheduled light battery charge (blue and red lines) but, bizarrely, in the first 5 minutes, the SOC (purple line) drops from around 17% to ZERO, WITHOUT ANY CORRESPONDING CHANGE IN CONSUMPTION OR OTHER OUTGOING POWER, then gradually goes up to around 6% SOC at around 03:20 at the end of this mysterious little charge cycle

Every time my battery charges and discharges, even though the minimum discharge level is set to 6%, it always overrides that and discharges to zero then recharges to 6%. Anyone know why that happens?

Gas plant efficiency is far worse than theoretical because of renewables fluctuations

if my calcs are correct a 20% glycol mix will reduce efficiency by around 2%. Important for fully informed choices. Water Cp 4.18 Fernox HP-5c @ 20% 4.085 -2.3%

yikes - storms mainly?

Surely it's similar to the English scheme whereby you can apply for the 7500 grant for a self build if it meets certain criteria

Going away soon. For a week's holiday at this time of year, how do people set their heat pump modes, temps and timings, and with what objectives in mind?

Agreed where we are talking about replacing a perfectly good boiler system. But if it's 30+ years old like mine was, and needs a major upgrade anyway, the net cost to me of a new ASHP, DHW tank and bigger rads was no different to a modern upgraded boiler system. That financial equation of course varies enormously from the cheapest (possibly one of the utility companies like Octopus) to the most expensive (premium expert installers such as Heat Geek)

and an oversize heatpump like mine working 10% more efficiently than a smaller one running flat out/less efficiently on freezing cold days will mean 10% less electricity use at the time when the grid may be well over-stretched. I don't understand why people would burden themselves with additional expense and complexity of adding heating elements, boiler hybrid setups etc. when all you need is a bigger heat pump. Imagine a family during the recent freezing cold spell, they all come down with flu or lurgy of some kind (very likely this season). The house temp needs to be increased a couple of degrees all day and night to give them all the chance to get well again. In those circumstances you need a level of headroom similar to what you got from a boiler. This is just one of the many advantages of an oversized heat pump - extension, faster DHW reheat, less defrost recovery issues etc. etc.

Modern scroll compressor / clever software controlled heat pumps just don't suffer the cycling inefficiences of the bad old days. For me there was no difference in installation price between an 8.5 and an 11 so I went for the 11 and glad I did. It is outperforming spec on cold days by a significant margin. Compare 10% inefficiency on a mild day of say 10kWh consumption compared to 10% better efficiency on a cold day of 100kWh consumption. It's unlikely to be worse than break even over the course of the season. That's definitely what the evidence is saying for mine.

why exactly?

why not just get a bigger heat pump

what's the problem with it being a little louder than whisper quiet for relatively tiny periods of time. The compressor on mine after defrost is barely audible, and I'm sure it's no quieter than the Vaillant