Strange jumps in measured room temperature

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Strange jumps in measured room temperature

Postby HarmOtten » Sun Dec 17, 2017 5:07 pm

Strange temperature jumps_.png
Strange temperature jumps_.png (50.03 KiB) Viewed 845 times

As you can see in the chart, it jumps up +/- 1,5°C at a certain temperature, and jumps down later during the night.
I have no idea what is causing this behaviour. But as you can see it is quite reproducable. I'm quite sure this wasn't the case without the OTGW.
I checked with a second measuring device to find out that the 1,5°C higher temperature is incorrect.
The wrong temperature is also visible on the thermostat itself: Honeywell Chronotherm Modulation T8851M1000.
Does anybody have an idea what is causing this? Any help is much appreciated!
HarmOtten
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Re: Strange jumps in measured room temperature

Postby hvxl » Wed Dec 27, 2017 4:31 pm

It is unclear what the source is of the data that you display in your graph. However, it is unlikely that this is caused by the OTGW on its own. Also, my T8851M1000 never behaved like this. Either something is sending some strange command to the OTGW, or something is otherwise interfering with the thermostat. Do you have anything connected to the RT terminals of the thermostat? Is there something near the thermostat that switches on between 16:00 and 6:00 (guessed from your graph) and produces heat?

The occurrences appear to happen at the same time every day. (The OTGW doesn't have a clock, so it wouldn't be able to do that even if I wanted to.) So it should be relatively easy to capture a log of such an event.
Schelte
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Re: Strange jumps in measured room temperature

Postby HarmOtten » Fri Dec 29, 2017 3:24 pm

Thanks for your reply!
The source of the data of the chart are the Room Setpoint (0x10) and Room Temperature (0x18) messages received from esp-link.
I have nothing connected to the RT terminals of the thermostat, only A and B are connected to the OTGW.
The temperature around the thermostat does not change so rapidly like the chart displays, and there is no other equipment nearby.
It looks like it happens every day at the same time, but that is just a coincidence.
I can actually see the same (wrong) temperature on the display of the thermostat. So I am getting more and more in doubt, that this issue might have been the case before the OTGW was installed, but back than I could not measure the temperature that accurately.
I will first try to figure out if the thermostat is wrong.
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Re: Strange jumps in measured room temperature

Postby HarmOtten » Mon Jan 15, 2018 5:33 pm

I did a simple test, just removing the gateway from between the Central heating and the thermostat. Then the measured temperature on the thermostat is correct! in this case 18°C. After connecting the OTGW, the measured temperature is immediately incorrect, in this case 19°C, which is too high.
As you can see in the chart above, this issue starts every time around 17.7°C or higher, and stops when the temperature falls below 16.8°C.
I do not know the cause of this, but I suspect there is something wrong in the OTGW firmware.
Hope you can help!!
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