Room thermostat for heatpump

Hi all,

We’ve changed our 2 LPG boilers for a Samsung heat pump. It’s working well but looking at it’s energy consumption pattern I think I need to change my Hive (Smart) room thermostat.

I say that because I believe I need to make the heat pump run for longer so I think I need a thermostat more like an old-style bimetal one where the on & off have a dead zone between them. This will hopefully then let the heat pump run for longer and drop it’s energy consumption from 5kW to 2kW more. Alternatively something digital which allows logic like heat to target +0.5 and allow to cool to target -0.4.

I could also reduce the temperature of the water output from the heat pump but it’s on a weather compensation curve but I reckon if someone took the time to define it for the UK then it’s probably worth having?

We have manual TRVs on 21 of our 23 radiators. We have a Hive TRV on 1 radiator in the bedroom to stop it getting too warm.

So, what I think I need is a thermostat which:

  1. Is proven to work well with heat pumps
  2. Potentially gives me more than 6 time periods in a day (we’re using 6 and I want 7)
  3. I potentially can control from an app (not essential but I hate the thought of heating in the evening if we’re not in)
  4. I potentially can apply my programming skills to (not essential)

Interestingly it looks like the Samsung wired remote control can do the temperature granularity thing so I could move it to the living room but it doesn’t have any internet connectivity so I think I should look for something else.

Recommendations and advice welcome!

Hello @christian good question, it’s usually a good idea to use the controller that comes with the heat pump for control as they are usually designed well to do that job with the heat pump in mind. I think the Samsung heat pumps have a modbus connection, it might be worth looking into options for control via home assistant or something like that. Alternatively I know https://passivuk.com do controls for Samsung heat pumps with what is quite a nice app, but not sure if that’s something you can buy off the shelf?

@johncantor has also been investigating heat pump control using a cheap wifi thermostat available on amazon which might be of interest.

I’ve been doing my own thing with my EcoDan heat pump here HeatpumpMonitor/HeatpumpController at master · openenergymonitor/HeatpumpMonitor · GitHub it’s just a personal side project at the moment not anything near being product ready…

@TrystanLea, thanks; I would definitely try the Samsung control if it had any internet connectivity but I called their support (about extracting data to emoncms) and they said it’s all proprietary. I told them I was disappointed.

My installers suggested a look at passivuk.com when I asked about MMSP but it looks to be a B2B proposition. I’ll call them on Monday anyway.

I did wonder if I could create my own logic in NodeRed (driven by my EmonTHs) and call for heat using wifi-mqtt-relay-thermostat?

NodeRed will work well, although the recent trend is to advise running it separately from the emonPi. I have it on my emonPi and use TPlink HS100 wifi plugs which are low cost. To make a “wifi relay” (e.g. for a heatpump control input) I use HS100 + spare 9-12V wallwart power supply + £2 relay from eBay.

Also consider https://www.homelyenergy.com/ - expensive but works well with my ground source heatpump. I bought the Homely box when I was on the Octopus Agile tariff but it continues to control the house temperature well now that (like most Agilers) I switched to Octopus Go.

@Steve , that’s really helpful, thanks. I don’t see a Samsung option at Homely so I’ll look further into the wifi relay option.

I see Samsung at Homely now, but am still tempted to grow my own.

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