How do you control the central heating temperature in a smart home via RS485?

Question

Hello everyone I’ve recently become interested in the topic of smart homes... I’m no expert when it comes to plumbing. However, I’ve come across some uncertainties regarding room temperature control. Smart home systems use controllable outputs to operate solenoid valves or a manifold. As far as...

mikroflota · Answer

Both the “LAN” and the RGB controllers are at fairly advanced stages of development. Nexwell’s latest launches are scheduled for the Securex trade fair. As for heating, in basic systems the boiler only regulates the water temperature, whilst the home automation system manages the distribution of that water. In other words, it closes off those circuits that are warm enough and opens those that need further heating. By design, the water leaving the boiler is at a significantly higher temperature than the returning water. The boiler’s control system compares these and adjusts the power output accordingly. There isn’t really much scope or need here for deeper communication with the boiler via RS. Although such possibilities probably do exist, and it’s sometimes worth making use of them. It’s just that these options are rather limited, and there are probably as many different software solutions as there are boiler manufacturers offering RS-485 connectivity – each requiring customisation for a specific model… unless I’m mistaken…

pawcio-w · Answer

''Assuming that the system only controls solenoid valves, I’m wondering about a situation where the smart home system closes the heating valve for a particular heating zone because the occupants are away (to save energy, e.g. by reducing the temperature by 2 degrees)

From what you’ve written here, I understand that solenoid valves plus some sort of controller regulate the room temperature. In that case, the boiler should be set to a constant water temperature in the central heating system or controlled based on the outside temperature.

‘The boiler will detect the falling temperature and will try to raise it...’

With this solution, the boiler shouldn’t measure the temperature in the house; you’d be duplicating the control.
As for communication with the boiler, however, I have no idea :cry:

grudziu · Answer

Smart home systems use controllable outputs to operate solenoid valves or a manifold. As far as I am aware, temperature regulation in a central heating system is not achieved solely by regulating the flow of water (fluid).In that case, how can the water temperature in the central heating system be controlled using a smart home system?

control of the central heating system can be handled by the boiler’s automation system. And the benefit of local control stems from the fact that less heat is released into the rooms, so the boiler consumes less energy to maintain the set temperature for the central heating system

Is it possible for smart home systems to communicate with boilers or room thermostats via RS485? If so, what about transmission compatibility?Assuming the system only controls solenoid valves, I’m wondering about a situation where the smart home system closes the heating valve for a particular heating zone because the occupants are away (to save energy, e.g. by reducing the temperature by 2 degrees), the boiler will detect the falling temperature and attempt to raise it....

Personally, I implement home automation systems based on two open standards – LonWorks and KNX/EIB. In both cases, there are boilers (e.g. Buderus, Viessmann) fitted with communication modules. There is full compatibility – the devices are visible within the same software. This means that the room thermostat communicates in the same ‘language’ as the boiler, lighting, roller blinds, etc.

Regarding local control:
Closing the valve – e.g. in accordance with a PI algorithm and the setpoint temperature. The setpoint temperature is reduced by -3 degrees in night mode according to a schedule.

I’d also like to add that I’m considering the Nexo system from Nexwell. I’m not sure whether this system supports LAN and internet connections for monitoring and control purposes. I also suspect that it doesn’t support RGB lighting control…
Best regards

I’m not familiar with this system, but there are two things I don’t like about it – its centralised nature and its closed architecture. I suspect the price, on the other hand, is an advantage

mikroflota · Answer

As for centralisation, it is true that decisions are made by the system’s central unit. However, the system utilises independent bus devices mounted on a standard electrical installation (there is no need to create special cabinets or switchboards for the automation), which, in the event of communication problems or a system failure, retain their autonomy and mimic the behaviour of a conventional, non-smart electrical installation. This is a compromise solution in case of an emergency. As for the ‘closed’ nature of communication between microprocessor-based devices, this is also true; however, on the other hand, the system is open in terms of accessories and offers integration possibilities with a much wider range of products than those dedicated to the open KNX and LonWorks standards. Viessmann and Buderus do indeed have devices compatible with these protocols, but they also provide other access points allowing integration with ‘closed’ systems. I am referring here, for example, to the FM456 function module (Buderus), the ZM427 add-on module (Buderus), the Logamatic Easycom PRO (Buderus), the VitoCom 100 (Viessmann) and the VitoCom 300 (Viessmann).

grudziu · Answer

What do you mean by ‘accessories’?Is Nexwell a Polish product?

KarolW · Answer

Please explain how the Nexo system works with these modules, particularly with Easycom PRO. I know this module has inputs and outputs, but what about readings such as temperature and visualisation on the Nexo system’s LCD terminal? Is what you’re saying theory or practice?
I’d also like to join my colleague’s question about accessories.
This is very important information for me, as I will soon have to choose a system.

mikroflota · Answer

Accessories – I was referring to 95% of the installation range on the market, i.e. input/output devices. If you connect a thermistor directly to the system’s input, you have a temperature sensor. Connect a photoresistor, and in Nexo you’ve got a sunlight sensor [though there’s nothing to stop you using ready-made devices with a 0–10V output, or simply NO/NC contacts]. Connect a standard keypad and you have an alarm keypad. If a manufacturer of more sophisticated equipment (heating boiler, furnace or air conditioner) offers potential-free inputs, you can easily integrate them into the system. If a manufacturer of a particular piece of equipment provides normally open communication outputs [e.g. an error message], on the Nexo Panel you can set up a pop-up message with an audible alert, plus send the content of that message via text message, etc., etc... Nexwell is a company with 100% Polish capital and technical expertise. Production is also 100% Polish. I’ll reply as soon as I have a spare moment. As is usually the case with the topic of heating, this whole matter could end up in a long discussion, so I need to think about how to explain the so-called ‘integration with the stove’ issue in a reasonably clear way. Perhaps in the meantime, Karol, you could explain what exactly matters to you regarding this integration.

mikroflota · Answer

Before I get to my answer, I’d like to point out straight away that this is a very complex subject, and the knowledge I have – which I’ll be sharing here – is only a small part of the issues involved in integrating heating with IB systems. So, if anyone has any comments, please address the content of the post rather than pointing out errors. This is a truly serious subject, and one could probably explore and expand on it endlessly...

In general:

IB systems regulate and control room temperature using solenoid valves (relays or 0–10V outputs to the relevant solenoid valves) or electric heaters (heating mats, oil-filled radiators, other electric heaters). Control is based on temperature sensors located within the rooms and a control programme for these heating elements linked to the relevant IB system. This is the basic form of room temperature regulation and, as such, does not require integration with the central heating boiler because:

a) the boiler is an independent unit with its own automatic control system, which it adjusts autonomously to the current aggregate requirements of the heating circuits.

b) the water temperature in the heating circuits is generally set on the basis of a separate external sensor (outdoor temperature sensor) [these are usually simply suitable thermistor models] or a heating profile set directly in the boiler controller (night [economy] mode / day [normal heating] mode)

However, there are certain methods for more sophisticated integration of the boiler with the IB system.

a) settings for the heating profile
b) transmitting temperature information to the boiler (alternative to the weather sensor)
c) integration of messages from the furnace into the IB system

Point a) can be implemented via potential-free contacts if the furnace manufacturer provides them (in Buderus, this is presumably the furnace’s ‘WF’ input)

Point b) can be implemented, for example, via a 0–10 V input, although I wonder why, given that an external thermistor is probably the most appropriate solution (Alternatively, the status of this sensor could be monitored via the IB system. [In the Nexo system, this is done via an analogue input])

Point c), i.e. monitoring of the boiler’s fault messages, is carried out via the normally open contacts of the boiler’s sensor outputs. [In the Nexo system, the activation of such an output can be linked to a test message displayed on the touchscreen or an SMS informing the owner of, for example, excessively high temperature or gas concentration, or low pressure in the system.]

***
As for the Easycom PRO controller, I am not entirely familiar with how it works, but the options suggested by the manufacturer regarding SMS control (reportedly available only in the version for the German market) and DTMF already allow for control via the NEXO system. However, as it turned out, the basic and sufficient methods of integration with NEXO do not require additional controllers, and the heating control system can be successfully implemented in a general manner, including alarm functions and night/day mode using the standard set of inputs and outputs on Buderus boilers. Finally, I would add that the issues discussed here apply to systems fitted with a single boiler. Apparently, any additional controllers offered by boiler manufacturers such as Buderus become relevant when the heating system is designed to manage multiple boilers and, I suspect, multiple flats or premises.

robja · Answer

My building control system provides independent management of the boiler room (boiler, central heating, heat buffer, fireplace with a heat-retaining jacket, domestic hot water, ventilation with heat recovery, etc. – dedicated controller (HeatManager) – the boiler is only switched on if the heat buffer cools down to a programmable threshold
as well as independent room-by-room control via the individual activation of solenoid valves for heating (room controllers – RoomManager).

Additionally, the system can be programmed by the homeowner themselves (on the PC managing the system)

I’ve had the eHouse system in my home for 6 years (manufacturer’s website eHouse smart home )

I highly recommend it.

shorti13 · Answer

A warm welcome.I’m a complete novice when it comes to building automation, but I’d like to put in my two cents. I was once looking for a solution for smart ‘home’ control. I came to a few conclusions: 1) Controlling heating from within the IB system is only feasible with KNX/EiB. This is because the boilers have KNX or LON gateways (KNX-to-LON gateways do exist), and from the home control level we have full control over the heating. This is a very expensive solution. 2) If I can’t afford a KNX-enabled boiler, I can control the valves instead, and here one might be tempted to use what I call ‘proprietary’ systems (manufactured by a single company), but this comes with a rather significant problem – what happens if that company goes out of business? We’d be left without the option to expand or repair the system. That’s why, for valve control too, I’d choose KNX as a system whose components are produced by many financially independent companies. 3) As for cutting costs and bypassing KNX, I’d ignore heating control at the IB level and leave it to the boiler manufacturer. As for the rest of the controls (lighting, blinds and so on), I’d control them using any system, provided it’s based on routing the circuits to a single distribution board, as there are at least several systems that offer this kind of control. Advantage: in the event of a fault, you’ll still be able to switch the lights on somehow, but you’ll be left in the cold. 4) If I were to set up a control system for myself without heating, I’d go for a PLC controller – cheap, simple and reliable. If a company were to carry out the installation for me, I’d opt for the most widely used solution.These are opinions from a consumer’s perspective, not an expert’s. For the project I was looking for a solution for, we chose a stripped-down, budget version of KNX with cables laid for future expansion; only now has a touchscreen panel become available – a very nice one at that (ABB Comfort Touch and heating control – but only via the valves, without interfering with the boiler itself. In other words, KNX activates the ‘away from home’ mode on the boiler. I don’t know the details. Ultimately, we plan to install a GIRY home server and view footage from IP cameras. I know that AXIS cameras work with the ABB panel. However, I’m wondering if there’s a video doorphone compatible with KNX. We’ve got round this problem. I’m interested in a dedicated solution.

mikroflota · Answer

I’ll take this opportunity to respond to a few of shorti13’s comments, which, to put it diplomatically, are greatly exaggerated:

Quote:
1) Controlling heating via the IB system is only possible in KNX/EiB.

As I wrote above, heating control can be achieved by regulating the power supply to individual heating circuits. As for integration with the boiler’s automation system, whether and how the boiler can be controlled by external IB-type devices depends largely on the boiler’s design and the manufacturer’s policy. As for an exemplary controller design – in my opinion, not a KNX-based one – take, for example, the NIBE Fighter1245 heat pump. I hope other manufacturers will follow suit [excerpt from the technical documentation in the attachment]. Not only does Nibe provide 5 contactor inputs on its pump control unit, but it also allows you to select which specific tasks a given contactor should perform during the pump’s operation. On top of that, of course, there’s an output with an alarm function. Solutions more or less similar to this are becoming increasingly common on the market when it comes to boilers, air conditioners, heat recovery units, etc. No KNX gateways are required.

As for the manufacturer’s ‘preference’, that is another matter entirely… Simply put, boilers, by their very nature, should not allow too much scope for manipulating the fuel combustion process… mainly to protect the user from potential harm resulting from excessive or incorrect interference.

Another thing is that sometimes it’s claimed that something is a KNX controller, but when it comes down to it, it turns out to be just ordinary binary inputs/outputs, which I suppose any IB system can handle.

Quote:
If I can’t afford a KNX-compatible boiler to control the valves, one might be tempted to use what I call ‘proprietary’ systems (manufactured by a single company), but this comes with a rather significant problem – what if that company goes bust? We’d be left with no way to expand or repair the system. That’s why, for valve control too, I’d choose KNX as the system, as its components are produced by many financially independent companies.

That is indeed a valid point. It’s just a shame that products from the KNX consortium are so expensive that one could easily order (for particularly cautious customers) a 100% stock of spare parts, and it would still be cost-effective. As for servicing and repairs, this is generally electronics based on fairly tried-and-tested and popular technologies, so I imagine any workshop that repairs any sort of control unit would be able to handle the servicing. Another point is long-term service contracts. Not every customer is aware of this, but any manufacturer that decides to work with an institutional client signs a long-term contract for the servicing and maintenance of the installation in question. Of course, KNX offers the greatest peace of mind in this regard, but it is probably not proportionately expensive (since even integration with boilers via a gateway is a dead-end service, as hardly anyone would agree to such a costly solution). As for development… Expandable installations were created because the upfront cost of the whole system is simply too high. In the case of these ‘proprietary’ solutions, the development of the IB system stems more from a fascination with the technology than from financial constraints… although that does happen too, and the possibilities in this regard are by no means any less.

Quote:
3) When it comes to cutting costs and bypassing KNX, I’d skip controlling the heating via the IB and leave it to the furnace manufacturer. As for the other controls (lights, blinds and so on), he controlled them using any system, provided it involved routing the circuits to a single distribution board, as there are at least several such control systems available. Advantage: in the event of a fault, you’ll still be able to switch the lights on somehow, and you’ll have heating.

As for ignoring the heating and leaving the boiler alone, I’m in favour of that – or rather, against it

I also partly agree regarding the centralised system. Whenever we bring everything back to the distribution board, whichever system we choose, we’re left with the luxury of being able to manipulate these resources almost at will. It’s just that there’s one fundamental problem… Centralised systems are very labour-intensive, costly, and their size can grow to monstrous proportions even for homes that aren’t particularly large. Here, I’d like to mention Nexwell’s TUKAN technology, which adapts to the infrastructure of a standard electrical installation. These devices operate independently of the system’s control unit, so a potential fault does not cause an electrical blackout in the home. Retaining the infrastructure typical of a standard electrical installation is precisely what allows you to prepare your home for smart home technology at low cost.

Quote:
I do, however, have a question: is there a KNX video doorphone?

Still not available? I thought it was practically standard in new builds by now...

Knopka · Answer

Hello,I’m new to the forum and wanted to say hello to everyone. Winter has arrived quite quickly, so I thought I’d dust off this topic. All the more so as I’m giving serious thought to installing a smart home system in my house. Having read your posts and those on other forums, I’ve come to the following conclusions: 1. If I’m on a tight budget, I need to find a Polish system, as KNX and similar systems are quite an expense.2. Communicating with the boiler doesn’t make much sense if I can switch off the heating circuits using solenoid valves. The boiler can always be switched off by controlling the mains socket, or alternatively controlled using a 0–10V signal. These are certainly cheaper yet effective solutions. 3. I want to be able to control everything from a single device. It could even be a computer if that would work out cheaper. 4. The system must also support additional ‘extras’, such as an alarm, a fire protection system and lighting. But I’ll write about that in another thread when I have a spare moment, so as not to stray too far from the subject of heating

KarolW · Answer

Perhaps Nexwell’s system would be right for you. It’s a centralised system, but it offers some rather interesting solutions. The build quality is excellent.

Knopka · Answer

I’d considered Nexo before, but it didn’t really take my fancy. A centralised system ought to have some sort of safeguard in case of a loss of connection with the control unit. If only to implement some simple fail-safe logic. There are a few other details as well, but there’s no point going into them at length.

Now that Nexo’s off my list, I’m considering Xcomfort, or something more advanced – Vision BMS. I still need to think carefully about what I need, but for now, Vision’s on my mind.

As for the heating, I intend to control only the solenoid valves. The boiler will run non-stop, set to a constant temperature. It should be fine

mikroflota · Answer

Sorry, Knopka , but I have to speak up, as you may not have noticed a few technical features in Nexo. The Nexo system is centralised at the software level of the automation system, whilst at the hardware level it is decentralised and allows for the connection of 4 Tukan buses;each of the buses is galvanically isolated from the rest of the system (safety measure 1); each TUKAN bus device has a bus fuse, which protects the hardware against connection errors and bus short circuits (safety measure 2); each Tukan device that operates using a relay as its actuator has NO and NC contacts. This means that at the installation stage, a decision must be made as to whether, in the event of a fault, the natural state of the relay should be closed or open (safety measure 3); Each Tukan device that operates using a relay as its actuator allows for easy replacement of the relay (it is mounted on a base) should it suffer natural wear and tear after many years (safety feature 4); Each device responsible for switching on lights or opening roller shutters has a local input allowing the relevant circuit to be activated via a wall-mounted switch, regardless of whether the device is communicating with the rest of the system or not - It features a processor-supported standalone operating mode (safety feature 5) Furthermore, an 8-channel relay module is due to be added to the range in the new year; this will allow direct control of the relay coil (this time independently of the processor) via a DIP switch; (safety feature 6) The architecture of the entire system is designed so that the failure of any single component does not adversely affect the other components. (Safety feature 7) Knopka, sorry for going off on a tangent, but Nexo really does have a few solutions to tackle the ‘crisis candle’ issue. That’s all from me. Best regards, and I hope I’m not getting in the way – this was supposed to be about heating.

Knopka · Answer

What you’re describing are fairly standard solutions; besides, as you yourself pointed out, they relate to hardware security measures. What I’m interested in is combining this with software. In other words, I need the ability to define a (programmable) fail-safe logic in case communication with the central unit fails for any reason. The I/O devices should respond to input signals as I have previously programmed them to, controlling the output signals and so on.

Heating is also a good example here – I’d like to be able to specify how the heating control should operate in the event of a loss of communication with the central unit. It would also be useful to be able to intervene manually in such a case (via GSM?).

As for the Nexo itself… do the ‘tukan A’ and ‘tukan B’ designations on the bus have anything to do with RS485? Or are they perhaps not the same thing?

mikroflota · Answer

Well, that’s more or less the case, albeit to a rather limited extent. I’d describe this scope as 1:1. In other words, a single local input – for example, from a roller shutter module – is capable of lowering and closing the roller shutter in a software-defined manner (lowering times, operating mode, etc.), even in the absence of communication with the control unit. But in this case, a single button is specifically assigned to a single circuit. The aim of this is to ensure that, even in the event of the worst-case failure (the central unit), the user retains the convenience of using the electrical system in much the same way as with a standard, non-‘smart’ installation. Well, I absolutely agree with you on this point; Nexo can’t do that. However, the bar is set very high… I’m not sure, but I reckon that only fully distributed systems could have this capability, and even then only if they’re configured wisely. But to be honest, I’m not even sure about that. There is a rather clunky but effective way of doing this. There is a Nexo system that has a duplicate central unit with an identical configuration. Any switchover in the event of a failure takes place automatically via some sort of external controller. I’ve no idea how this is implemented. At this stage, manually switching over to the backup unit could take about a minute, as all the motherboard connectors have to be unplugged. Yes, in terms of hardware, it is a technology based on RS485; in terms of software, it consists of several proprietary protocols, with the exception of the open Command Card protocol based on ASCII encoding.

Knopka · Answer

As you say, the scope is limited. As far as I’m concerned, this isn’t a fallback solution at all.

I’ve been looking around the market for a while now and I know that centralised systems are capable of this sort of thing. Vision BMS is just one example.

Hehe, so the Tukan bus is nothing more than RS485 plus a power supply. Not bad marketing

Let’s perhaps wrap up the discussion about Nexo, because that’s really not what this thread is about.

Sparroł · Answer

Hello, I’d like to start by saying that I’m no expert in smart homes and I’m just looking for specific advice on how to solve the problem of remotely controlling a circulation pump. At the moment, I’m controlling the pump using a standard timer, but it’s a bit of a faff. I’m looking for a solution – not too expensive – that would allow me to switch on the pump from anywhere in the house (which has three floors). I need five switches and, of course, a device to control the pump itself. This could be done via a LAN or some other method; it simply needs to be reliable and easy to use.

Best regards, and apologies for my lack of technical expertise

kasprzyk · Answer

Let us know what sort of “nuisances” you’re currently experiencing, and we’ll try to sort the problem out Regards

Sparroł · Answer

Hello kasprzyk,
The problem is controlling the so-called hot water circulation pump. My initial idea was to have it running non-stop, but what’s the point of it cooling the water? Despite the insulation, there are always losses, and it’ll wear out the pump, not to mention the electricity...
I’m thinking about some sort of on-off system that would work – controlling the pump without using cables, as it’s too late to lay them now. Perhaps Wi-Fi or something along those lines; I’ve got Wi-Fi at home. Specifically, there would need to be ‘on/off switches – controllers’ in at least five locations – four, to be precise – and ideally with some sort of indicator (on the switches) to show whether the pump is running or not. And finally, perhaps battery-powered (though not necessarily).

thx

PROAT · Answer

And that’s all there is to it. For controlling the pump: the CSAU-01/02 receiverFor switching on as required – either via a digital input, a temperature sensor or a button – all wireless.

kasprzyk · Answer

The point is, what do you mean by a not-too-expensive Leaving aside the issue of water cooling, I’ve calculated the ‘electricity’ costs generated by a 22W circulation pump – it works out at around 96 groszy per month when running in cycles between 6 am and 10 pm. If I’ve understood correctly, you want to be able to switch it on manually on every floor? Think this solution through – you’ll have to remember to switch it on every time before entering the bathroom; it defeats the purpose to spend money on a relatively expensive control system for ‘such convenience’. The most convenient option would be wireless motion detectors fitted in the bathrooms – along with a small alarm control unit, e.g.:

How do you control the central heating temperature in a smart home via RS485?

How can a smart home system control central heating temperature, and does it need RS485 communication with the boiler or thermostats?

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Considering Xcomfort or Vision BMS with valve-only heating control

Considering Xcomfort or Vision BMS with valve-only heating control

Nexo provides decentralized hardware with seven fail-safes

Nexo provides decentralized hardware with seven fail-safes

Programmable fail-safe control during communication loss

Programmable fail-safe control during communication loss

Programmable local fail-safe logic for communication loss

Programmable local fail-safe logic for communication loss

Centralized systems support heating control; Tukan uses RS485

Centralized systems support heating control; Tukan uses RS485

Seeking reliable remote pump control with five switches

Seeking reliable remote pump control with five switches

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Wireless multi-point control for hot water circulation pump

Wireless multi-point control for hot water circulation pump

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Wireless bathroom motion detectors automate circulation pump control

Wireless bathroom motion detectors automate circulation pump control