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FGT-001 Fibaro Heat Controller, external sensor evaluation, part 1


petergebruers

Question

I write this topic to help you decide if you want the "external sensor" (+ 15 EUR, +10 EUR bought as a bundle)... To avoid confusion: the FGT-001 does only displays temperature if you add the external sensor. Without the sensor, it displays "--". But that is not the main reason to buy one... You might have heard the TRVs cannot measure temperature accurately, because their sensors are "not in the right spot". But the question is... how bad is it? I encourage you to have a look at the setup, the graphs and, if possible, repeat the experiment. For me it is clear: I wanted the external sensor for the FGT even before I did the experiment, based on experience with older Danfoss valves. But this is not a general advise, it probably depends on a lot of factors.

 

Part 1 is this topic. I'll show you graphs of the temperature "in the room" and "near a valve". So you can decide for yourself. In "Part 1" I do not use my FGT yet! I compare the result of different temperature sensors in the room. I only want to know if they match.

 

Part 2 is not available yet, because the FGT has a bug that causes it to behave erratically. I'll publish results after running tests with the firmware release that will fix this. In "Part 2" I'll establish if the FGT + external sensor (a) does measure accurately (b) can control room temperature.

 

DISCLAIMER. "My room" is not "your room" and certainly insulation and heating system are different. If you want to make sure, please do your own measurements (and post them so we can all learn from your experiments).

 

Setup and measurements.

 

I have a DS18B20 sensor connected to a Z-Uno. It reports temperature every few minutes (after running it through a filter for smoothing). It is attached to my mechanical TRV, like this:

 

Please login or register to see this image.

/monthly_2017_12/ValveSensor.jpg.9dcac03e760143164475f0a902763e0d.jpg" />

 

As you can see, I really did "bugger all" to make this a professional solution, sorry, no time to waste... It is a temporary setup anyway. However, the measurements will be fine.

 

Now I need a reference device. I did slightly more than "bugger all" because this device has been my temperature reference since 2012. It is a DS18B20, probably from the same batch, but connected to a Fibaro UBS. I mounted it near "the sofa". Hence its name... "Sofa"...

 

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First, let us see if the sensors need calibration. So I mounted the valve sensor in the same spot as the sofa sensor.

 

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I would say they are identical. I am not a mathematician, I am an engineer, we have a different definitions of the concept: "the same".

 

So now let's put the valve sensor back as shown in the first picture.

 

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Let's see if I can explain what we see. The valve sensor = red almost always registers a temperature that is too high.

 

The left part of the graph is "the evening". If we ignore the dips on the graph, I'd say the sofa measures 1.5 - 2.0 °C lower. Is this plausible? Yes, when I used an LC13 on that radiator I had to set it about 1.5 higher.

 

The sudden drop and the right part of the graph are caused by two things: turning down the TRV and opening a door. The room next to this one is cooler (TRV is an LC12, controlled by the heating panel).

 

As you can see... For about one hour the TRV measures a temperature below the sofa sensor. I live in a could house, the TRV is close to a window. Temperature at the TRV drops quickly and the sensor does not have a lot of thermal mass (or digital filtering). The sofa sensor is probably not experiencing the same level of air flow (it is near a wooden panel).

 

At around 6:00 temperature increases in the other room, then I also increased the setting on the valve a bit (it is a mechanical valve). this explains the last part of the blue line.

 

Based on this graph I'd say the valve sensor is inaccurate, and I do not see a simple solution. Neither an offset, nor a gain correction can make the red an blue graph "fit".

 

Let's have a look at another time segment.

 

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Again, overall, the valve sensor reports higher temperatures.

Can you see I have trouble sleeping? Yes, at 4:00 I increased the temperature setting of the valve.

I cannot explain the complete graph, because I did not write down time and set-point of the valve. For comparison of the two sensors, this is no big deal.

 

Please note all graphs use the same temperature scale, because that is what we are trying to compare. But they do not use the same time scale.

 

Conclusion. In my house, in this room, I agree with the statement:TRVs cannot measure temperature accurately, because their sensors are "not in the right spot". So I understand why an FGT without external probe does not report temperature. It could do that, but then you would have to understand its limitations.

 

An FGT-001 with a sensor near the sofa should be able to control temperature more accurately. Whether this is important is up to you. I have learned to live with mechanical TRVs and LC12, LC13 without external sensor. I expect the FGT-001 plus external sensor to increase the comfort level. But right now, I really do not know. How people experience temperature is really complicated... Temperature control is only part of the experience...

 

Edit:

 

@Lode mentioned other sensors in the same room. Here is a graph of three sensors. The red and blue are the same (valve and sofa) and the third one is an FGMS-001 mounted roughly 0.5 m below the ceiling.

 

I think it is hard to say wether it better matches the sofa sensor. When you look at 1/3 of the graph and compare blue-black at 2/3 of the graph I'd say a simple offset will not do the trick. But as a rule of thumb, it measures about 1,5 °C higher because of the difference in height.

 

Please login or register to see this attachment.

 

@robmac made it clear to me... my topic title might be a bit misleading at the moment, because "Part 2" does not exist yet. So here's some more information.

 

12 hours ago, robmac said:

I replaced the Danfoss valves with three fibaro FGT-001 and one Fibaro external temp sensor. I am not particularly interested in accuracy but your charts are a bit concerning as they appear to show a lack of consistency. I am not sure I am seeing the same issues.

 

They should be concerning... But maybe there is a possibility of misinterpretation of my post and my graphs. I probably caused this myself, because the topic title is misleading. In hindsight. It says "FGT-001 Fibaro Heat Controller, external sensor evaluation, part 1". In fact, in part one, there is no FGT-001. And because of that, there is no external sensor either!

 

I compare three sensors in my room, while there is only one plain old TRV. And my point is exactly what you say: (a) Old valves do not perform well in my setup (b) it has a lot to do with the fact that an old valve has no other reference than the sensor inside its head. And indeed, may stuck-on "valve sensor" does not match either my FMGS nor my SOFA sensor. It is not an absolute temperature test. It is only a comparison of references. Because this is a mechanical valve, I could have noted each time I adjusted its setting. But I did not, because I was not really interested in the performance of this old, mechanical valve.

 

When Fibaro releases a firmware update, I'll redo the measurements, with external sensor. I hope to see the room temperature (aka SOFA) will be under control and will be stable and also match the set-point of the heating panel.

 

12 hours ago, robmac said:

My temperature sensor tracks the  Horstmann (Secure) thermostat temperature when placed beside it allowing for the different update interval and reporting sensitivity. I placed the sensor beside the Horstmann at 17:45 and by 18:00 it was tracking within 0.5 which is not bad.

 

I think as an absolute temperature sensor, the FGT-001 is quite accurate, the spec says +/- 0.5 °C and I have every reason to believe that. I could produce some graphs like the ones you posted. I'll think about that... I did have a quick look at the accuracy of the external sensor, but I did not save the data because I thought, it meets its specification, not much to tell about it. In part 2 I'll put the FGT external sensor next to my "SOFA" sensor and they should match. They also should match the programmed temperature.

 

12 hours ago, robmac said:

Is there any chance your issues are environmental.  Drafts would impact devices with different housings differently for example?

 

Absolutely... I have thought about explaining this. The short version: old house, not well insulated, two rooms 4x4 with a door that is mostly open, some chilly weather in Belgium (around 0 °C) and some western wind. Doors sometimes open, number of people in the room vary, ... So the absolute performance depends on so many factors! So Part 2 will be exiting, because then the FGT should try to keep the temperature near the sofa at the expected level! So when I write part two, I'll make notes of the exact circumstances.

 

Edited by petergebruers
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Guest Lode

It's complicated......

In my livingroom i have a netatmo wheatherstation.

There is always a difference from about 2 or 3 degrees between my thermostat  and the temperature from the netatmo.

Netatmo is placed near the TV and about 1 meter lower than the themostat so quite normal but.....

I do have a woodstove and when that is on the difference between both devices is about 5 or 6 degrees.

So the difference between floor and ceiling can be very different, depending on a lot of facts like Peter said already.

 

I ordered the new fibaro Heating thermostat with temperature sensor and will place that just near my normal thermostat on the wall,  1.5 m above floorlevel in a small plastic box so the influence of the environment is minimal. I will do some tests a publish that.

 

 

 

 

 

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  • 25 minutes ago, Lode said:

    It's complicated......

    In my livingroom i have a netatmo wheatherstation.

    There is always a difference from about 2 or 3 degrees between my thermostat  and the temperature from the netatmo.

    Netatmo is placed near the TV and about 1 meter lower than the themostat so quite normal but.....

    I do have a woodstove and when that is on the difference between both devices is about 5 or 6 degrees.

    So the difference between floor and ceiling can be very different, depending on a lot of facts like Peter said already.

     

    Thanks, nice to see I got you inspired to have a critical look at temperature reporting...

     

    Because you mention a third sensor, I've added this to my first post:

    On 12/21/2017 at 3:09 PM, petergebruers said:

    @Lode mentioned other sensors in the same room. Here is a graph of three sensors. The red and blue are the same (valve and sofa) and the third one is an FGMS-001 mounted roughly 0.5 m below the ceiling.

     

    I think it is hard to say wether it better matches the sofa sensor. When you look at 1/3 of the graph and compare blue-black at 2/3 of the graph I'd say a simple offset will not do the trick. But as a rule of thumb, it measures about 1,5 °C higher because of the difference in height.

     

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    Guest Lode

    @petergebruers I do have a very critical look at temperature reporting because a difference of one degree can reduce or rise your energycost significant.

    I've always been told that the best height of placing a wallthermostat is about 1.5m above groundlevel so for a temperaturesensor it must be the same.

    This is also the reason i don't understand why a motionsensor, smokesensor etc.  do have a build in temperaturesensor. In my opinion useless even when you can adjust the temperature. 

    In the past i'v been testing this with the Netatmo.

     

     

     

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    My Opinion !

    I bought this thermostat the moment it was available.

    To me it is essential that it shows the inside temperature.

    I want to know that hot water is reaching the specifik radiator. If it is cold, I want to know that it is working (by setting up the waterflow and heat). If it is too hot; I want to see that the inside temperature is falling. 

    I would like to be able to see this on my phone !     If a part of my watersystem is either frosen or clocked or the boiler is stopped, I want to know.

    If I had known that this did not work I would not have bought it, then I could have bought a Danfoss witch is a great thermostat but it does not report inside temperature either.

     

    By the way. I use a Vera system and there is some problems integrating it with Vera, please help them to get it integrated soon...before Winther is over ! ?

                         I would also like to know how I can update the firmware when I use a Vera ?

    Regards CE

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  • @svaleb I value your opinion.

     

    Unfortunately I cannot help you, I can only advise you to return the thermostat or pay 15 EUR to get the extra sensor. I cannot decide for you if it is worth this extra money, but you do mention that accuracy is very important to you, so... I started this topic to make people aware of the difficulties of measuring temperature and it is unfortunate my topic was posted after you bought your thermostat...

     

    Please start a new topic for questions about vera. This topic is about temperature measurement.

     

    I can answer one question though... at the moment, vera cannot update the firmware (also, when I write this, there is no update). So you'll have to ask your seller, installer or a friend with a HC.

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    Very interesting topic.

     

    I would like to give my five cents into this.

    Have setup 7 Fibaro TRVs in 5 rooms, all rooms with extra trv sensor.

    All rooms with Fibaro Motion Sensors, with temperature threshold report of 0.5 degrees.

    Also Fibaro Door Sensors, tuned to 0.4 threshold.

    In the Livingroom, I also have old fashioned Thermostat Temperature Sensor, which I observe is most accurate to temperature changes.

     

    What I observed is TRV sensor reports very slowly, and try to keep almost same temperature, even the difference in room temperature may vary with 2-3 degrees. Which became advantage right when I did average temperature measurement from all room sensors.

    The averages went into sync with my old good thermostat measurement.

     

    When rooms get heated, upper motion and door sensor get "hot", but trv sensor doesn't allow average to go up fast, and opposite. When room door get opened, or the cold coming from the wall near motion sensor reports getting cold, again trv keeps the average up. Till trv sensor moves, or other two sensors gets really hot/cold, warning for big difference coming...

     

    Finally was able to do my call for heat script running well for me.

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    @ petergebruers

    Thanks for your answer !

    I will look elsware in the forum.

    And I would still like to have the temerature information from the thernostat head.

    Regards CE

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  • 3 hours ago, svaleb said:

    And I would still like to have the temerature information from the thernostat head.

     

    I understand. The lack of reporting without extra sensor has been noted, and Fibaro is aware of the fact you (and a few other posters) are disappointed. In theory, they could fix that in firmware, they have made no promises. I hope my post explains why this value would be inaccurate (*)... I am not saying it is pointless, but inaccurate... If Fibaro would report the temperature of the integrated sensor, I would still buy the external probe, because in my house, in my room, that would give me better temperature control. In theory. Because at the moment a firmware bug prevents accurate control anyway so that is why I plan a follow-up on this topic.

     

    BTW you have mentioned you would like to use the built-in sensor for diagnostic purposes (not for control). Accuracy would indeed be of lesser importance. 

     

    You might want to check this related topic regarding temperature control and valve diagnostics:

     

    (*) To be more precise: it is inaccurate when you want to measure "room temperature". It is probably quite accurate in the absolute sense (better than +/- 0.5 °C). The sensor just happens to be in the wrong place to represent the temperature of that part of the room I'm in... It is not a matter of adjusting or calibrating either, you can see on my graphs you cannot simply apply some math.

    Edited by petergebruers
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    Hi @petergebruers

     

    I love your scientific approach.

     

    My less scientific findings:

     

    I have a room that has always struggled with  Danfoss valves due to comms issues to the HC2. Three rads in a room measuring  6.5m * 6.5m. I replaced the Danfoss valves with three fibaro FGT-001 and one Fibaro external temp sensor. I am not particularly interested in accuracy but your charts are a bit concerning as they appear to show a lack of consistency. I am not sure I am seeing the same issues.

     

    My temperature sensor tracks the  Horstmann (Secure) thermostat temperature when placed beside it allowing for the different update interval and reporting sensitivity. I placed the sensor beside the Horstmann at 17:45 and by 18:00 it was tracking within 0.5 which is not bad.

     

    Please login or register to see this attachment.

     

     

    What I am seeing is a lot of overshoot that I find a little worrying.

     

    The rads were not fully off until this point. That is a 2.3 overshoot.  I have re-calibrated all three valves now to see if that improves this behaviour. I am also not sure if the valves learn the nature of the heating rate over time and adjust the control profile to improve overshoot. I will track both temperature and overshoot over time and see if temperature remains consistent and overshoot improves.

     

     

    Please login or register to see this attachment.

     

    Is there any chance your issues are environmental.  Drafts would impact devices with different housings differently for example?

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  • @robmac thank you for joining the discussion!

     

    24 minutes ago, robmac said:

    I replaced the Danfoss valves with three fibaro FGT-001 and one Fibaro external temp sensor. I am not particularly interested in accuracy but your charts are a bit concerning as they appear to show a lack of consistency. I am not sure I am seeing the same issues.

     

    They should be concerning... But maybe there is a possibility of misinterpretation of my post and my graphs. I probably caused this myself, because the topic title is misleading. In hindsight. It says "FGT-001 Fibaro Heat Controller, external sensor evaluation, part 1". In fact, in part one, there is no FGT-001. And because of that, there is no external sensor either!

     

    I compare three sensors in my room, while there is only one plain old TRV. And my point is exactly what you say: (a) Old valves do not perform well in my setup (b) it has a lot to do with the fact that an old valve has no other reference than the sensor inside its head. And indeed, may stuck-on "valve sensor" does not match either my FMGS nor my SOFA sensor. It is not an absolute temperature test. It is only a comparison of references. Because this is a mechanical valve, I could have noted each time I adjusted its setting. But I did not, because I was not really interested in the performance of this old, mechanical valve.

     

    When Fibaro releases a firmware update, I'll redo the measurements, with external sensor. I hope to see the room temperature (aka SOFA) will be under control and will be stable and also match the set-point of the heating panel.

     

    34 minutes ago, robmac said:

    My temperature sensor tracks the  Horstmann (Secure) thermostat temperature when placed beside it allowing for the different update interval and reporting sensitivity. I placed the sensor beside the Horstmann at 17:45 and by 18:00 it was tracking within 0.5 which is not bad.

     

    I think as an absolute temperature sensor, the FGT-001 is quite accurate, the spec says +/- 0.5 °C and I have every reason to believe that. I could produce some graphs like the ones you posted. I'll think about that... I did have a quick look at the accuracy of the external sensor, but I did not save the data because I thought, it meets its specification, not much to tell about it. In part 2 I'll put the FGT external sensor next to my "SOFA" sensor and they should match. They also should match the programmed temperature.

     

    39 minutes ago, robmac said:

    Is there any chance your issues are environmental.  Drafts would impact devices with different housings differently for example?

     

    Absolutely... I have thought about explaining this. The short version: old house, not well insulated, two rooms 4x4 with a door that is mostly open, some chilly weather in Belgium (around 0 °C) and some western wind. Doors sometimes open, number of people in the room vary, ... So the absolute performance depends on so many factors! So Part 2 will be exiting, because then the FGT should try to keep the temperature near the sofa at the expected level! So when I write part two, I'll make notes of the exact circumstances.

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    Hi @petergebruers

     

    I now understand. I should have realised from the images.

     

    I have also now read your other posts. Possibly my overshoot is also a firmware issue. Will wait for update and retest.

     

    Cheers and a happy new year to you.

     

     

    Robert

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  • @robmac thanks, and I wish you lots of fun with HA.

     

    I've added your questions and my answers to post #1 - for "the greater benefit of all".

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    @petergebruers

     

    Thanks again for your answer (29 DEC)

    Looking forward to the update.

    I can see that others are concerned about updates when using other controllers (as vera)

    I am sure they will find a solution. I have been happy with other fibaro devices, but it take Vera too long time to integrate them...sigh.

    Happy New Year

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  • I removed this post because I suddenly realized I was hijacking my own topic. :D

    Edited by petergebruers
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    Hi Peter,

    i now have 7 valves. Danfoss lc_13, Devolo Lc_13 and Eurotronic spirit sometimes with motion eye or netatmo  as external sensor. I work on it for over a year (2 heating periods).

    I'm absolutely with you about the use of an external sensor. But I wonder about your what robmac calls "scientific approach."

    All of the above mentioned valves have their own Logic? alogorithm? or better say "they do what and when they want". If you raise temperature for 1 ° manually at the valve something happens, sometimes or not and tomorrow vice versa.

    Even here in Fibaro Forum most of the people have the opinion fibaros heatcontroller don't work at all. So I stop investigation about how to configure a usefull heating control and wait for a functional valve. Maybe fibaro will create one -- somedays.

     

    regards

    Gerhard

     

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  • 42 minutes ago, ggoetz56 said:

    i now have 7 valves. Danfoss lc_13, Devolo Lc_13 and Eurotronic spirit sometimes with motion eye or netatmo  as external sensor. I work on it for over a year (2 heating periods).

     

    Thank you for chiming in! That is a nice setup.

     

    42 minutes ago, ggoetz56 said:

    But I wonder about your what robmac calls "scientific approach."

     

    I went through the effort to setup a test (see post #1) with several sensors, collect data and posted graphs, temperatures and I try to explain what I see. You can call it "scientific". I think that is what he means.

     

    44 minutes ago, ggoetz56 said:

    All of the above mentioned valves have their own Logic? alogorithm? or better say "they do what and when they want". If you raise temperature for 1 ° manually at the valve something happens, sometimes or not and tomorrow vice versa.

     

    Yes indeed. I own LC12 and LC13 and now I am going to make a non-scientific statement ;-)

     

    I think they are "slow" in several ways. Relative to LC12 the FGT is fast in my opinion. I said I would not share data based on this firmware and I have not changed my mind about that (yet).

     

    47 minutes ago, ggoetz56 said:

    Even here in Fibaro Forum most of the people have the opinion fibaros heatcontroller don't work at all. So I stop investigation about how to configure a usefull heating control and wait for a functional valve. Maybe fibaro will create one -- somedays.

     

    People do not come here to say: "wow! what a nice device, I am so happy" - they come here to get help, or maybe even complain. I'm talking in general terms, it applies to the FGT but also to, for instance, FGD-212 aka "dimmer 2". If you search on this forum, you might think all led bulbs "flicker" and nobody can use this dimmer. I am not allowed to publish numbers, but I can tell you less than 1% of all users experience some issue (like flicker...).  It does not work with all bulbs, but then there are so many different led bulbs, transformers, ... on the market! I can personally recommend dimmer 2, it is very robust (protections), has lots of configuration options... In fact, I think so far nobody posted "my dimmer 2" died on this forum... But yeah, we can expect a firmware update for the FGT... Let's see how good it is when we can test it...

     

    So, back on topic... You use "netatmo" to control some valves... Would you say: "it works better than the valves on their own because netatmo is an external sensor and a better reference" (so you agree with post #1)? Do you have some data to share? Or do you disagree?

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    Test

    I pushed the submit button 3 times but nothing happend

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  • 2 minutes ago, ggoetz56 said:

    Test

    I pushed the submit button 3 times but nothing happend

     

    I think I know what you mean... sometimes "save" on a post can take several seconds... Maybe even 10 seconds... Or do nothing at all (but that is rare for me).

    Edited by petergebruers
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