Hi Andrea,
Sorry that you’ve had no replies to your questions.
I’m not so sure that I am best placed to offer advice, as I don’t have experience of the monitoring products on sale through OEM, or of Homely, or even the various electricity tariffs. But FWIW I have found that:
- The Samsung remote controller (the MIM-E03*N) displays – as opposed to monitors – all the info you need to optimise your setup (i.e. instantaneous heat generation and power consumption, thus CoP). Setting Water Law – FSV #2011/2 and #2021/2 (or #2031/2) – such that your house is just warm enough over a range of ambient temperatures, should get you 90% optimised without the need for a separate heat meter. I did install one (a Sontex because I have glycol, which cost me about £500 including installation cost/VAT), because I have a buffer tank and wanted to know what heat was actually entering the house rather than leaving the heat pump. But using it I found that 1) external heat losses were virtually negligible (about 150W on a really cold day), 2) the Samsung LWT and RWT temperature instruments and the circulating flow instrument give reasonably accurate results (compared with the heat meter) if averaged over time. and 3) the Samsung-published performance data for my model (HTQ, not Gen 6) were fairly consistent with my readings.
- You don’t say whether you have a battery, but I suspect that you would need one to make best use of off-peak tariffs. I have no idea how Octopus Agile works in practice, but I have considered Octopus Cosy (3 low-tariff periods + 1 high-tariff period each day). By charging the battery (as well as running the heat pump flat out) during the low tariff periods you can ride through the high tariff period from the battery and making use of the house thermal inertia, even if you cook in the evening with electricity when the high-tariff period occurs. You wouldn’t need Homely for this – you could just set your roomstat programmer to switch off the heat pump during the high-tariff period. Also, a Homely for Samsung would cost about £360 (Midsummer Wholesale price, plus any installation cost) and in my case my electricity cost is so low (< £700 per year) that I doubt I’d get a financial payback, not to mention all the faff of setting the thing up. Long and short, so far I’ve decided to stick with an Octopus all-day tariff.
- If you do want some heat pump monitoring, without risking putting your data onto the Internet (and thus potentially being vulnerable to hacking) you can do this at low cost (under £100 all-in) by installing an RS485-to-Ethernet adapter on your MIM, and recording the controller inputs/outputs (both Outdoor and Indoor Units) on your computer for later analysis. If you are interested in this I can give you details (recommended hardware, step-by-step installation instructions) on request. The Excel spreadsheet that the Samsung software generates is really useful to understand what is going on (cause-and-effect analysis), and allows you to change your FSVs from your computer without touching the remote controller.
- Regarding glycol, have a look at Glycol: pros and cons. This offers some opinions (from experienced, if rather biased, community members). Personally, I’m sticking with glycol, mainly because if the frost valve operated (or malfunctioned), I’d lose my heating completely until I’d 1) figured out why the heat pump tripped on apparent low circulation flow, and 2) I’d recharged the circuit (with potential air-locking problems) or installed a replacement frost valve. (For me the big downside of glycol is that I can’t modify the circuit, such as a replacement radiator, without recovering and re-injecting the glycol, which is a pain. The changes in physical properties between water and glycol – density, viscosity, thermal conductivity – are fairly minor, and I doubt that I would spot the extra circulating pump power consumption or reduced heat pump condenser performance.)
Good luck with the service!
Sarah