Home heating automation

ECO_Mental

Hi Fellas

The thing is with my setup is that I have a very well insulated and airtight house that gets good solar gain as well and in theory I should need very little heating. I'm just after switching to a smart tarriff and I want to shift as much of my HP consumption to the very low EV rate and avoid the peak rates. As the saying goes if you go out and try and save money you mightn't save energy, but if you save energy you will always save money…

My house is also fairly open plan down stairs so it makes no sense having one of the thermostats calling for heat in the living room and the kitchen (which is open to the living room) not been heated at the same time. If the HP is on then its on, I want it heating a few rooms at least. Its just a bit of a pain the arse going around to all 12 and making adjustments to the time schedule or set temps.

My heating strategy at the moment is I have HP blasting away between 2-5am, the first hour is just for DHW and then between 3 and 5 the heating is on. At 6.33cent per kWh its ridiculous value, from the graph below the heating part it was chugging away at 3kW but outputting 12 kW in heat (COP of 4) there was only 8.5 kWh last night so it only cost me 53 cent!. I know there are some nights I might not need it but all that thermal mass built up lasts me into the evening time, where at the moment I have it coming on for an hour just after the peak rates just to give it a boost up. Am I saving energy that's debatable but I am certainly saving money….I haven't my Shellys set up yet (just one) I am still waiting for them but It might be Christmas before I install them all (They are from Santa😎)

To see if I am actually saving energy I did regression analysis of the last 2 years of my HP energy usage, Heating Degree Days vs HP kWh, but its only showing an R value of 0.65 (not that great). Basically based on how cold its outside I can calculate with 65% confidence how much energy I should use. See the graphs below, the dotted line is the predicted energy usage based on how cold its outside. During the summer and shoulder months its not that accurate because the heating is off but during the winter its fairly good predictor.

At the moment I am just testing a few simple automations to turn on and off the heating, but I will try and be a bit more sophisticated especially in the evening, there are some evenings I probably don't need it on at all, but as it is its set to come on for an hour or so so I just leave it. I also need a better thermostat, those Aquara Zigbee ones are useless and no where near as responsive as they should be for controlling heating. I am getting a Shelly Wifi one that updates every 5 mins.

Keep ye posted

deezell

https://www.boards.ie/discussion/comment/122908462#Comment_122908462

All the mental energy invested in controlling, monitoring, and interpreting your setup probably keeps you warm! A modern version of the old proverb, 'He who chops his own firewood warms himself twice'. Precisely what I did yesterday to warm up before the Ireland Australia test, sawed and chopped my way through a quarter ton of ash dieback logs. I shouldn't have bothered, the match boiled my blood anyway. Keep up the good work.

ECO_Mental

https://www.boards.ie/discussion/comment/122908502#Comment_122908502

II'd say it's more a hobby at this stage doing all that analysis and automating stuff...keeps me interested in the evenings. If I did nothing it would be grand also I like doing type of things messing with Home Assistant.

Shane732

went with the one from above

deezell

https://www.boards.ie/discussion/comment/122911056#Comment_122911056

Kit 3, thats the one.

RonnieL

Hi folks. I hope this is the right place to ask this question. I have a standard two story house in an estate, built in 2003. We've got a gas boiler, which was replaced a couple of years ago, at which point we got "upgraded heating controls". So, we've got two heating zones, upstairs and downstairs and the water is the third "zone". We have an app called "Ember" on our phones, and we use that to set thermostat temperatures, and schedule/boost the zones. Our radiators have basic TRV's but they're generally all just set to the max.

I'd like to make the system smarter. For example, we have a playroom that doesn't need heating in the mornings, but nobody is bothered going in there turning off/on the radiator or adjusting the TRV's. Similarly, we have a stove in the sitting room, but we sometimes want to have the heat on in the rest of the downstairs, but not in the sitting room when the stove is lit.

So, my question is, what options do I have to add some smarts to my setup?

deezell

Does your Ember app just control timing of the Hot water, or is there a reading of HW temperature? Ember is one of a few controllers which can optinally read and control HW temperature as well as set timing on the app. Most smart systems will just turn the HW on and off with a set schedule, and use a mechanical thermostat clipped to the HW cylinder or inserted via probe to set HW cylinder temperature during a scheduled time slot, as there is no real need to vary the HW temperature over time.

RonnieL

https://www.boards.ie/discussion/comment/122926836#Comment_122926836

There is a reading of temperature in the app, and a thermostat on the wall outside the hot press. I'm not really worried about changing the water heating schedule, but I would like more control over which rooms are heated in the house and when.

deezell

OK. That device is an Ember wireless HW cylinder thermostat. It instructs the Ember controller to interrupt a HW timed call for heat when the HW cylinder temperature reaches target. It can be left in place if you leave the Ember controller in charge of HW only. It would be tidier though to replace all the Ember equipment. The ideal system in your case is the Drayton Wiser kit3, 2 CH and HW controller, with two wireless CH wall thermostats. This will drop in neatly in place of the Ember controller. You can then add individual Drayton smart TRVs to radiators you wish to program in and out of the general zone schedule. Look out for some offers on these, there were some black Friday deals.

Your HW will be timed only, but you can get a mechanical cylinder thermostat to set a temperature cutoff to the HW zine valve.

TheSunIsShining

https://www.boards.ie/discussion/comment/122899591#Comment_122899591

I've never managed to get a proper handle on this from Tado - the 1 tick, 2 ticks and 3 ticks. For those of us with a standard boiler, you'd assume it's either getting a call for heat or not. But I don't know what the 1 tick does - what I thought would be binary, on or off, doesn't seem to actually work like that

deezell

https://www.boards.ie/discussion/comment/122937444#Comment_122937444

On off is how a dumb mechanical thermostat works, it stops firing when the measured temperature passes threshold, it start firing when temperature drops below. With a mechanical stat there is considerable lag or hysteresis, as it can take several degrees either side of target to turn the stat on and off. Add this to the overshoot caused by the fully heated rad continuing to heat after the boiler turns off, and the continued cooling on firing as the flow must heat up before the rads can have an effect, you can have a room temperature which goes up and down by several degrees. Even electronic stats which can trigger on or off on a fraction of a degree difference will have this latter issue.

Smart thermostats use a number of techniques to achieve and hold a steady temperature. PID control is one, predictive learning is another, and to facilitate this is variable rate of heat delivery. As the boiler can only deliver heat at a constant rate, a method known as modulation is employed. This is your 1 2 3 tics, whereby the boiler will cut and restart even though target is not reached, but is approaching, in oder to land smoothly on the target temperature. Once there, the same technique is used to mini boost the boiler though temperature may be above target but falling, so that the temperature does not have a significant lag.

Most cheap electronic stats and many general pupose automation sensors will lack these features, or may require programming to achieve more accurate control. Smart stats will also use learning to determine the rate of heating or cooling dynamically, and also in conjunction with local weather temperature readings. It all makes for a more comfortable experience, and removes the incentive to be a human thermostat, constantly leaping up to nudge the stat up a few degrees, pulling it right down as the room becomes uncomfortably warm, and repeat until bedtime.

TheSunIsShining

https://www.boards.ie/discussion/comment/122937858#Comment_122937858

So is it clear whether 1 tick in Tado has the boiler on or off?

deezell

https://www.boards.ie/discussion/comment/122937868#Comment_122937868

Both. A little on, a little off.

Roberto_gas

https://www.boards.ie/discussion/comment/122937868#Comment_122937868

one tick does not start boiler for me..it basically opens the valve and hot water in the closed loop manages to maintain temp for some time before boiler is called on. I see heating on in the App with ine tick but no call to boiler

deezell

If the zone valve opens, then the stat relay is closed and calling for heat, but If the boiler doesn't fire it's because the boiler water set temperature has exceed its set point, and firing will only occur when the flow temperature drops. When the stat relay opens, the zone valve will close, cutting off the live voltage to fire the boiler. This is the only condition where hot flow continues to pump without the burner firing, also know as cycling.

TheSunIsShining

https://www.boards.ie/discussion/comment/122954351#Comment_122954351

To be fair, I've seen Tado with 1 tick, and the boiler is cold, but it doesn't come on. Same as other poster.

deezell

https://www.boards.ie/discussion/comment/122954512#Comment_122954512

Yes, 1 tick doesn't mean it not firing, but it may still not have exceeded set temperature, and will fire briefly and intermittently to put a burst of hot flow into the rads, then wait and watch the incremental rise. A basic stat that waits for the set temperature to reach the stat before cutting the boiler will often see the temperature continue to rise several degrees above due to radiators full of boiler temperature water. The modulation kicks in when thr measured temperature is approaching that set on the stat, which will move to the two tick then one tick mode, and off completely if the temperature exceeds set significantly, due to a schedule change to a lower temperature,or because of another source of heat like a stove, or ovens/rings in a kitchen. You can run your finger along the history graph and it will show set and actual temperature for any time, as well as the boiler tick setting and the source of control, schedule, manual or away.

Chopper Dave

Hi - wondering if anyone could advise on the following: I'm trying to replace a digital timer clock with the Tado Smart Thermostat and am a bit confused by the wiring. Our current timer allows us to set a HW or a CH schedule but there are only two wires apart from the Live/Neutral. I can't quite figure out how this works with the TADO set up as the labels on the old timer are CH ON and CH OFF where as TADO is CH NO, CH COM and CH NC

ongarite

Blue to Tado supply N

Brown to Tado supply L

CH Brown to Tado Supply CH NO

HW Black to Tado Supply HW NO

Tado purple cable from Supply L to CH COM

Tado purple from CH COM to HW COM

Chopper Dave

Thanks so much ongarite. I’d never have figured that out.

deezell

https://www.boards.ie/discussion/comment/122955661#Comment_122955661

Check also if the CRC dip switch is set to Gravity or Punped, then configure the Tado receiver to Gravity if the CTC is Gravity. Tado is pumped by default.

mik_da_man

Just wanted to say thanks again to you @deezell for the advice and help here.

Got a Wiser system set up today (Kit 1 &3) and it's a great job.

Just grabbing more rad thermostats now to give full control.

My electrician was scratching his head a bit about industrial relays in our fusebox, but I think it's mostly figured out now bar the HW valve control.

deezell

https://www.boards.ie/discussion/comment/122957164#Comment_122957164

Industrial electrical relays? Like something you'd find in a grow house 🪴 or a crypto 💰 mining farm. Ha-happy Xmas!

WildCardDoW

Can the Bosch Greenstar 4000 (GR4700iW) be wired with Tado (Extension Kit) and retain modulation?

Reading a few of the manuals (such as this) and it seems possible?

https://cdn.brandfolder.io/607DGEMS/as/bxgtx5kghgjrbcs4m68kqch/Extension_Kit_Manual_-_Low_Voltage_Digital_Installations.pdf

WildCardDoW

Possibly answering my own question.

Seems the solution is to go with the wired thermostat and bridge.

deezell

https://www.boards.ie/discussion/comment/122957436#Comment_122957436

If you're looking to connect the low voltage digital connection to the boiler, the wired stat has these terminals. The current extension kit has a UK or EU version, the UK sold here does not have the digital low voltage OpenTherm terminals implemented. It does have a HW relay for S plan motorised valve HW heating. In Europe they tend to only use combi boilers with direct HW, so the extension kit sold there lacks the HW relay, but does have the digital +- terminals implemented.

You can have the wireless version of the digital connection if you use this extension kit, but if you already have a wire pair from a standard mains Switched Live going to the boiler from an existing stat, you can reuse this wiring for a wired Tado stat, but you MUST ensure the pair is isolated from mains voltage. There may be a SL going from a timer to a wall stat and back to your boiler for example. Otherwise you can just install a fresh wire pair to the boiler Bus connection (below).

I'm assuming your boiler is a combi and has direct HW, or do you have a HW cylinder? And seperate zone valves for HW and CH?

xl500

Honeywell Evohome brilliant system

mik_da_man

https://www.boards.ie/discussion/comment/122957196#Comment_122957196

Lol.. I've no idea relay...

This is what they look like

deezell

https://www.boards.ie/discussion/comment/122957862#Comment_122957862

The labels MV probably refer to 'Motorised Valve', three CH zones plus HW, which might solve your electricians problem. I'm not sure why the original installer put the valves behind relays, they don't load the calling timer/thermostats that much. Maybe they're there as a logical OR gate to provide the combined boiler call Switched live from any of the 4 zones' SLs. This is normally achieved by using the built in relays inside the zone valve actuators, a call for heat to any MV opens, the valve flow opens, and the actuator closes a relay contact. These 4 relay outputs are combined and connect to the boiler SL in. It's my guess that the MVs used didn't have relays, so the 4 isolating electrical relays had to be installed to mimic the zone valves missing relays.

If I'm right, it's not a perfect solution, as the zone valve relays only close when the flow valve is fully open. If it sticks, no flow, no relay close and no call to the boiler. Let your sparks read this, it might lift the fog. The first relay marked 'sensor' might be triggered by a frost protection thermostat.

WildCardDoW

Yeah @deezell

Cylinder gone and removing zone valves as well. Have an old wired stat that I can use which should leave work as you've said.

I just noticed I can get the Tado X stuff from Germany for slightly more so might do that.

EDIT: X doesn't support HT Bus (yet).