Be careful what you wish for ‘smart’ doesn’t necessarily convert to intelligent when coupled with an ASHP. You could end up with the worst of all worlds. ASHPs need to run long and not be cycled on and off - many, if not all commercial smart thermostats will end up cycling due to very narrow dead zone as Christian mentioned. You’ll also find that if you want to make sure your ASHP is running only on a cheap overnight tariff, then the ‘smartness’ will thwart you. Our initial thermostats would turn on anything up to an hour before the scheduled time in order to get the rooms to the desired temperatures.
Would be interesting to hear from anyone that has found a commercial thermostat where you can adjust the dead zone to make sure that the ASHP runs efficiently. I’ve looked around and haven’t found one - so we use one where some of the 'smart’s can be turned off and we manipulate the schedule and target temperatures to meet our needs and the structure of the build. Ours isn’t a typical build at all - minority sport, this energy saving business - so there aren’t commercial thermostats on the market to suit our situation. And yes, I’ve looked in more energy conscious countries but still haven’t found anything. We’ve effectively got about a 1000 old fashioned storage heaters in our slab which unlike them is highly insulated…
So, the best bet for anyone trying to optimise a similar system would be to go the DIY route, as @borpin has done.
My “installer” has just E-mailed to say that " a new replacement “manager” has been appointed to replace Tony Dunn , the former “manager”, who was blamed , and fired, for the fiasco in installing my Samsung Heat Pump.
The new “manager” is trying to get Samsung to “inspect and repair” my Samsung Heat Pump.
Eight months and counting!!
The "instability " I have encountered with the Samsung could be reduced with the provision of a “Continuous” Thermostat control.
A suitable control could be interfaced using the Samsung “Intesys” KNX to F3/F4 converter. F3/F4 is the Samsung RS485 control bus.
Any Thermostat using a continuous KNX interface could then be interfaced to the Heat Pump.
At risk of being off-topic, I mostly Avoid thermostats because I run the house heating “normally Off”, “unless there are Renewables Available”, “except when it gets too cold”. The default heating plan is to go out for a walk, and the house quite often feels warm enough when returning to it.
I avoid thermostats because “a thermostat is a hypervigilent sales rep for the electricity company” which always tries to turn up the heating just in case someone might want it. I prefer to use heating mainly “if necessary”.
After that puritanical greener-than-thou claim, I did run the gas central heating for an hour this morning (and to get a hot bath) and I do presently have the air-air heat pump ( 0.7kW electrical 2.2kW thermal ) on in the room which I am in aiming for 21C at its built-in thermostat. Room temperature looks like about 19 or 20 C. It was about 14C in here overnight unheated.
I totally agree with your comments about the unexpressed, hidden, motive of the Energy companies in trying to get the user to spend as much as possible on Energy.
The Energy companies well know the importance of energy saving , but have an obvious motive to get the user to spend as much as possible on their energy!
I also, take long walks , with my walk preceded by Switching my Samsung Heat Pump into outing mode.
Outing Mode drops the Flow water Temperature to 15 C.
I also, further, have invested in an all over Thermal insulation outfit, with a not to fetching Thermal vest complimented with an equally not fetching industrial thermal Trousers.
Very interesting thread. I don’t yet have an ASHP but I have been researching towards getting one and shared the concerns expressed here over whether common smart thermostats were suitable such as Tado, Nest, Drayton, etc…
FYI - The Tado supports both ye olde call for heat control which would likely overshoot but also supports OpenTherm and eBus control. These are modulating control methods designed to prevent overshooting but not all heat sources e.g. older boilers supports this method of control and I have not been able to establish if any ASHP systems do.
Tado themselves say they do support ASHP but there is support and there is optimised for and clearly it sounds like it is not optimised for ASHP.
Resideo probably better known here as Honeywell have a new Evohome Smart Thermostat they claim is designed to specifically support ASHP as well as traditional boilers. See -
This based on their claim is interesting but I have not seen any independent reviews to substantiate this yet.
@iantelescope You apparently have a Samsung ASHP. I have been considering a Samsung Mono HT Quiet along with their ClimateHub but I cannot find any installers in the London area I would have confidence in. Would you or anyone else here have any suggestions?
With regards to Samsung ASHP any thoughts over whether to just stick with their own thermostat?
Now, today, I am probably the last person on the planet to advise anyone to use an “installer”.
My “installer” having been STRUCK OFF TWICE in the last six months.
I do not know of the London situation for Heat Pump Installations, but would advise that you do not trust the guarantees provided by the MCS,NIC and the RECC.
Thermostats
Just buy a simple Honeywell Home device costing circa £80.
Get your Heat Pump up and running with the simple Thermostats.
Do NOT initially buy a “Smart” Thermostat.
Above all , be careful , the renewable industry company half life is less than three years!
I’d go to a clean sheet of paper; “what do I Really need?” because the answer which I got was Not to remove anything. The £5k government incentive to spend £10k more than you might need to, is a distraction. I only Added to house heating capabilities, and added to diversity of supply, with the air source heat pump (ten years ago) providing heat to the living room only. I never removed the gas central heating because that would be wasted effort. I just use it less, and in summer time not at all.
Ah, no - I have a “simple” Honeywell thermostat, but it tries to modulate the heating system like a boiler, which makes the heat pump cycle way more than it needs to. Far better to have a thermometer in the room that tells the heatpump how warm it is, so it can decide the optimum flow temps.
Unfortunately, These professional Thermostats use the KNX Bus , with a KNX to Samsung/Mitsubishi et al completely unaffordable and would bypass the Samsung controller!
So, Does anyone know of a Affordable Thermostat that has the functionality of the Zennio?
Flow Water Temperature control ?
With Weather compensation is not my Flow water controlled by the Outside Air Temperature Sensor?
Part of the issue for me is the resolution. For me 0.1°C makes a big difference. I know it sounds daft, but I can tell if the room is showing as at 20.2°C or 20.3°C. Thermostats with a 0.5°C resolution just don’t work for me in my main room heated by UFH. A resolution of 0.5° and a delta of 1° is effectively a 2° window.
My former “installer” has not responded to either myself or the NIC.
The NIC has reverted to it’s advice that I seek legal advice.
Apparently, “nothing can be done”!.
With the half life of companies in the Renewable industry being less than three years I fully expect my former “installer” to change his company name , appoint new directors, usually the wife , and emerge as new startup in the “exciting Renewable industry”!.
I am, with justification , become a crabbit Auld man!.
Bus to the outdoor controller!
The Samsung controller “talks” to the Outdoor device using the F1 and F2 Bus.F1/F2 is Probably another version of RS485.
Buses from outdoor controller to MODBUS destinations
The Outdoor controller uses a RS485 to Modbus ( RS485 ) convertor, the Mim-B15N.
Buses to OEM devices
OEM devices , must use a ModBUS to F1/ F2 Convertor, the MIM-A60UN.
Given that I already use Home Assistant, I took a different approach. It’s a 70’s semi with wet CH. All rads have Z-Wave thermostatic valves, and each of the rooms we control has an emonTH - that’s livingroom, two bedrooms and the study.
Home Assistant has “virtual” thermostats for each room using the emonTH as the sensor and a “We need heat” boolean as the controlled switch (not the rad). If any room has asserted its “We need heat” boolean, then the boiler fires.
The rads themselves are controlled separately based on the room thermostat’s set point. This allows for an offset to be programmed. For two of the rooms, the rad needs to be 0.5C higher than the desired temp. For the third, it’s 1.5C.
Above all this is a control algorithm that varies the set points for each room based on a number of factors such as occupancy, open window sensor, time of day, season, whether we are home or not.
This system has been running for three years now and, apart from occasional tweaking, works well.
