Best practices for turning on/off a central heating system

Hardware
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an example photo, there are those that send a pulse per liter or those that send a pulse every 10 liters. Some are suitable for hot water but cost more. I hypothesized a meter so you can also measure the consumption of hot water but you could also use a flow switch that costs less precision tells you if water is passing or not

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:thinking: wonders if that might be a general recommendation?!

:+1:

One thing you could do would be to make the system smarter when you are away or have reduced/additional occupancy.

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First of all, I am a member of the male species. Which means my DNA prevents me from reading manuals...

Secondly we are talking about reading the installers manual of a central heating system. I don't know anybody - outside of this community - that reads such literature for fun :wink:

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Sadly. I do. If only to see if there are any wiring ports, hidden buttons/switches that could be ā€œfunā€ to see what they do. ( and occasionally to check that the installer did actually set it up correctly )

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Yes that is normal, because you are part of this community :wink:

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Me too! But I'm not sad! :slight_smile:

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...reminds me of flat pack furniture. I always rip open the box, assemble the furniture, and as a last resort if it doesn't work/look correct, I then read the instructions.

chair

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OMG - I bet you got a lot of flack for assembling it like that??
Did you do all four chairs like that, or just the first one?
However, your floor tiling looks absolutely perfect!
Minor comment, I would raise the washing machine up by 6.5mm so it lined-up with the top of the cupboard door on its left. It's probably my ADNCFGS syndrome kicking in (again).

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Most if not everything can be somehow made smarter and not just because the "stupid" has the "PID" integrated.

Anyway, @BartButenaers your current setup is not that stupid at all. To make it smarter may gain your happyness but the overall win may stay under your expectations. Try to do some calculations on that topic also.

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Chairs? Who mentioned chairs? I was assembling a table :thinking:

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How do you control the radiator temperature (i.e. what valves are you using)?

How did you train everyone to close the door when leaving a room? :smiley:

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I've never hear of a 'tank in tank' system until now, but it appears that fixing sensors to the outside of the tank would only measure the primary system water temperature, which would heat up very quickly, and bear little resemblance to your stored domestic water. So probably very little use.

However, it appears (from your diagram) that it would be easy to add some smart logic to control your home heating system (add a MQTT controlled shelly switch??).

You could then control it, for example;

  • Use a phone geofence to detect if anyone's home, and lower/raise the temperature accordingly.
  • Use 'node-red-contrib-google-smarthome' to add voice commands "Hey google, make it warmer/cooler", "turn the heating off" etc.
  • Calculate how early that the boiler needs to switch on each morning, by using current room temperature & rate of rise algorithm.
  • Control heating whilst away from home using NR dashboard/telegram/google home app, etc.

There are lots more ideas to try :wink:

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A post was split to a new topic: Help with Shelly

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Paul,

Build them like that again and you will end up on one of these :wink:

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Yes that is indeed the major disadvantage of my heating system. Did already discuss about that many times on Discourse over the last years, but never got time to work out an affordable solution.

I have a thermostatic valve at each radiator, which opens when its target temperature is not reached yet. So we have this kind of situations:

  1. My son increases the temperature on the thermostatic valve at the radiator in his study room.
  2. Then he needs to increase the temperature on the central wall-mount thermostat, to tell the pump it needs to start circulating hot water to all radiators. If he forgets to do that, his room will be cold when he wants to start studying.
  3. When he has finished studying, he should turn off the thermostatic valve in his study room. But sometimes he forgets to do that, and he doesn't notice it because someone else already lowered the temperature on the central wall-mount thermostat (which means the radiator in his study room will get cold anyway).
  4. Then someone wants to go to bath and raises the temperature of the thermostatic valve on the radiator in the bathroom, and he also raises the temperature again on the central wall-mount thermostat. The pump starts pumping and the bathroom gets warm. So far so good...
  5. However the study room will also start to get warmed up again, since my son has forgotten to turn down the thermostatic valve on that radiator. As a result we spoil energy and yet another discussion with the kids start ...

Which means that we use the central wall-mount thermostat only as a switch:

  • We turn the pump off by adjusting it to 0Ā°C
  • We turn the pump off by adjusting it to the maximum temperature.

So very far from convenient...

After I drawed the above diagram this week, it became very clear to me that I should buy a box of Shelly TRV's, so that every radiator can ask Node-RED to turn my pump on/off. My heating system contains no logic and can be controlled simply buy a few optocouplers. So I think that is the only way to go. But the TRV's are quite expensive, and I need a lot of those. And I am still negotiating with my wife about a series of extra camera's, so won't be for tomorrow...

BTW I know that there are cheaper TRV's e.g. based on Zigbee, but (as explained in the past) I don't want to have multiple wireless networks in my house. Case closed :slight_smile:

Nice catch!! That I didn't think about that myself... Thanks!!

Thanks for thinking out loud!!!!
Main problem is that I can't control my TRV's at the moment. Changing the temperature of my central wall-mount thermostat via Node-RED has not much sense, because the rooms (where I want to control the temperature) are too far away from the thermostat.

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When we moved in the heating was already arranged in zones controlled by individual thermostats attached to inline motorised Honewell 272848 valves (though I use much cheaper clones). In fact I haven't got temperature sensors on each radiator, where a zone has more than one radiator I control just the largest one and make sure the rest are well balanced so the one I am measuring is representative.

There are only two of us, and the unheated rooms are not used much so it isn't much of an issue. I can see that with a resident family this might be a major stumbling block.

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I achieve a similar effect by adjusting the temperature of the water (and heating) in 30 minute slots, this way I can control the temperature over the whole day and also each day has it's own slots. Even adding boosts when someone needs more water (Shower?)

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Hello,
Interesting case, if you like Shellieā€™s, you can try make a basic TRV with a basic thermal actuator powered with a Shelly one with additional temperature sensor in the room connected to Shelly one.

You can do this for the room of your son and the bathroom .
Then you can trigger the pump start when one of the radiator valve are open or the main thermostat is on . This mean that you need a Shelly module to read its status like a wall switch and trigger the pump.
I
Personally I would recommend using nodered to understand how it work but later code the logic in the Shellies sothat it can work independently from noderedā€¦ or if you plan to keep nodered as the master, think to have a redundant system or a backup solution when your hardware running nodered would be not available.

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Really, rooms should be at least occasionally heated through autumn-spring. In the UK anyway where we tend to have high humidity in the cooler months. Otherwise, you will tend to get mold and a general "musty" damp smell in the room.

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I see this topic has being going a while and had lots of input - thought I'd chip in - don't know if these are best practices, but this is what I've done.

I have a similar system, oil fired boiler heating a hot water tank - house is old and has had coal/coke fire, and later tank gas, and is now oil.

My system had a timer for heating on/off and hot water on/off. The heating on/off went to a programmable thermostat that allowed timed heating (if the first unit was set to permanently on).

These programmers turn on motorised valves, one for hot water, one for the central heating.
If the motors open the valves, they press a microswitch that turns the boiler on, and starts the central heating pump. So I can centrally heat the house, and or heat the water.

My radiators are fitted with manual TRVs.

The main heating on/off timer began to fail and I replaced the heating and hot water programmers with sonoff TH16s, flashed with Tasmota - approx 4 or 5 years ago.

I have cut a hole in the insulation of my hot water tank, and embedded a battery powered temp and humidity sensor that transmits at 433MHz - I have a RPi with SDR dongle running rtl_433 that reads the hot water tank temperature (it monitors the battery too and warns me if they need changing), and use node-red and BigTimer to run a schedule. I also use the SDR dongle to read lots of other sensors, eg oil tank level via oil watchman.

I have home made touch screen units that can turn the heating/hot water on/off on demand, or prevent hot water today, if not needed. These units also send room temp back to node red to allow it to determine whether heating is needed - these are averaged to avoid the chance of bad readings (I had these in the past using dht22 sensors, but now use BME280s without any issues).

I have a number of procedures in case of issues.

The boiler will run until the set temp is reached or a maximum boiler time is reached - to prevent indefinite heating in case something goes wrong with the hot water sensor.

I have tasmota on the Central heating and Hot water controllers set so that if they lose wifi or mqtt connections they turn on - in case I'm away in the winter to prevent bursts - the TRVs will then limit the house temperature.

If the heating is on, to prevent the boiler turning on and off too frequently I've set a minimum on/off period (10 or 15 minutes).

In case of a RPi failure (I have a spare hot swap unit and power supply) the timers in sonoffs are set as a fall back timer, though I would have to connect to them and turn those timers on.

If I'm not in the main room I can turn it's TRV down, go into another room and turn the heating on (touch screen in that room) and up it's TRV if required. My touch screens have pir so I could automate it to some extent, but I've not found it necessary as this doesn't happen often, though I have seen eg the Shelly TRVs but for my use case don't need them.

The Sonoffs have a manual on/off switch on them in case of systemic failure (I have spare flashed units just in case too).

I posted my flow in this thread a while back

and a photo of one of my home made controller units

My system evolved over a number of years, and continues to get periodic tweaks, but has run very well, mostly without issue.

HTH

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