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Thread: S-Plan vs Y-Plan for Evohome ?

  1. #41
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    While I'm at it, does anyone know how to change the seemingly hard wired 60 degrees Domoticz reports for the hot water set point when the hot water is ON ?

    It doesn't look like the hot water set point can be retrieved through the Web API, and I expected to see 60 hard wired in one of the domoticz evohome scripts but I don't see it anywhere. Domoticz treats the device as an ON/OFF device, so I'm not sure where 60 is obtained from for the purposes of graphing.

  2. #42
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    Re: Boiler Output

    Most boilers have a graph of gas consumption v output, that's how I adjusted ours, it's output can be varied from 18-25KW and BGas have this (annoying) habit of always turning the output to maximum every time they service the boiler. So, having determined by rough trial-and-error that the load for this property is nearer 20KW without creating a cycling boiler when it reaches flow temperature, I used the graph and gas rate on the meter by adjusting the burner gas rate (it's just a small screw) to the desired output. When BGas leave I adjust it back again - works for me.

  3. #43
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    I know where the kW output adjust screw is on my boiler, (beneath a cap nut) but I'm not touching it. I would have thought any gas adjustment like this is illegal for anyone not gas safe registered ?

    It seems to be set about right though, with all radiators on and hot water at the same time during initial warm up the temperature rise is steady but fairly slow, and it doesn't short cycle. With a lighter load it does cycle but as it is a non-modulating boiler any load less than full load will cause it to cycle on and off once it reaches the set flow temperature. I have a differential of about 5 degrees set on the external flow temperature controller.

  4. #44
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    Quote Originally Posted by paulockenden View Post
    I'll try to keep an eye on the Domoticz graphs/logs over the next few days, to see if I can capture for a DHW overshoot.

    At first sight though, it does look like a bug. Those with particularly high flow rates and temps from their boiler (basically those with high kw boilers) are likely to see quite a large overshoot, I'd have thought.
    How ironic.

    The following morning after I updated my domoticz patch to give full resolution hot water readings the problem kindly exhibited itself for me, and seemingly disproved my rounding theory!

    Here is the graph from this morning. Again ignore the 60 degree set point, my hot water set point is really 50:



    I hadn't previously noticed that Domoticz can also provide a CSV output of the readings, this provides much better clarity of the problem:

    Code:
    DateTime	Set Point	DateTime	Temperature
    31/10/2016 04:20	0	31/10/2016 04:20	39.48
    31/10/2016 04:25	0	31/10/2016 04:25	39.48
    31/10/2016 04:30	0	31/10/2016 04:30	39.48
    31/10/2016 04:35	60	31/10/2016 04:35	39.48
    31/10/2016 04:40	60	31/10/2016 04:40	45.34
    31/10/2016 04:45	60	31/10/2016 04:45	48.83
    31/10/2016 04:50	60	31/10/2016 04:50	48.83
    31/10/2016 04:55	60	31/10/2016 04:55	48.83
    31/10/2016 05:00	60	31/10/2016 05:00	48.83
    31/10/2016 05:05	60	31/10/2016 05:05	48.83
    31/10/2016 05:10	60	31/10/2016 05:10	62.29
    31/10/2016 05:15	60	31/10/2016 05:15	62.29
    31/10/2016 05:20	60	31/10/2016 05:20	62.29
    31/10/2016 05:25	60	31/10/2016 05:25	62.29
    31/10/2016 05:30	60	31/10/2016 05:30	62.29
    Hot water was scheduled to come on at 4:30 at 50 degrees, and Domoticz only samples once every 5 minutes. At 4:45 the temperature had already reached 48.83 degrees and would have been due to hit the set point before 4:50, however the temperature reading remained stuck at 48.83 right up until 5:10 - a full 20 minute delay in the reading updating, same as the previous two times this happened. The result of this is an overshoot to 62.29 degrees.

    My rounding theory is blown out of the water so to speak because the prior reading was actually less than 49 and would have been displayed as 48 on the controller as I've already established the displayed hot water temperature is rounded down from the true figure.

    So I'm left with the conclusion that either the sensor failed to send any temperature updates during the critical period from 4:45 to 5:05, or they were not received by or processed by the Evotouch for some reason.

    I double checked again - a full 5 flashes signal strength from the CS92, "Excellent" reported by the Evotouch for the hot water sensor, it's not within 300mm of anything metal or any BDR91's or other electronic devices, the signal is literally travelling about 7 metres through one wall (one side light density fire brick in the boiler cupboard, and plaster on the other side in the kitchen) and then a wooden door that is mostly glass to reach the Evotouch which is wall mounted in the hallway. You couldn't ask for an easier RF path in any normal house, and I have never seen less than a 5/5 signal test to any device around the house. I don't believe it is a signal strength issue.

    Maybe it's time to contact Honeywell ? The CS92 just isn't reliable enough for an 80 piece of kit.
    Last edited by DBMandrake; 31st October 2016 at 10:50 AM.

  5. #45
    Automated Home Legend paulockenden's Avatar
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    Didn't someone (it might have been you!) establish that the CS92 sends the data three times?

  6. #46
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    Quote Originally Posted by paulockenden View Post
    Didn't someone (it might have been you!) establish that the CS92 sends the data three times?
    During initial testing before doing the S-Plan conversion yes, it seemed to send an update three times about 10 seconds apart after the set point was passed.

    This was with a very rapid temperature rise from the sensor touching the side of a boiling kettle however.

    If it is supposed to do this then it almost seems as if the CS92 has "forgotten" what the desired set point is, and is sending its 3 transmissions at a lower temperature then sending nothing for a while ?

    I wonder if the CS92 remembers the set point when the batteries are removed and refitted (which has been done a couple of times in the last week) and if not when does the Evotouch re-advise it of what the set point is supposed to be ? Or would I have to change and then change back the set point in the installer menu to provoke this ?

    Or could it be if the temperature rises quickly it uses up its "allocation" of how many messages it can send in a given time period and is forced to remain silent for a while ? I think the spec does indicate that devices are only allowed to transmit for a certain percentage of air time - maybe that is being exceeded when the temperature rises quickly.

    Without an HGI80 to analyse the problem in more depth I can only speculate, and I don't really feel like buying another 94 piece of kit to troubleshoot an issue that shouldn't really be there.
    Last edited by DBMandrake; 31st October 2016 at 11:06 AM.

  7. #47
    Automated Home Legend paulockenden's Avatar
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    I don't think it has anything to do with your battery removal because, like you'll see in the graph I posted above, I can also see this issue over an extended period.

    Doesn't really bother me if I'm honest. No kids here, so a tap spitting out water that's a bit hotter than normal isn't a massive problem. But I can see how for others it might be.

    I'm not sure how Honeywell would fix it though. I don't think it could be remedied from the controller. And part of me wonders whether that three transmission thing means that someone was aware of this problem and tried to mitigate it to a degree.

    P.

  8. #48
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    Happened again today, so that makes 4 times in the 10 days since it was installed:

    Code:
    DateTime	Set Point	DateTime	Temperature
    02/11/2016 11:45	60	02/11/2016 11:45	45.53
    02/11/2016 11:50	60	02/11/2016 11:50	45.53
    02/11/2016 11:55	60	02/11/2016 11:55	45.53
    02/11/2016 12:00	60	02/11/2016 12:00	44.44
    02/11/2016 12:05	60	02/11/2016 12:05	49.45
    02/11/2016 12:10	60	02/11/2016 12:10	49.45
    02/11/2016 12:15	60	02/11/2016 12:15	49.45
    02/11/2016 12:20	60	02/11/2016 12:20	49.45
    02/11/2016 12:25	60	02/11/2016 12:25	62.67
    02/11/2016 12:30	60	02/11/2016 12:30	62.67
    02/11/2016 12:35	60	02/11/2016 12:35	62.67
    02/11/2016 12:40	60	02/11/2016 12:40	62.67
    Once again, there was a temperature update not long before the target of 50 was hit (49.45) then there were no further updates for exactly 20 minutes, by which time the temperature had overshot to 62 degrees. The fact that its exactly 20 minutes with no updates every time this happens makes me tend to discount the possibility of random interference.

  9. #49
    Automated Home Legend paulockenden's Avatar
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    Unless I'm reading that wrong you seem to have gone from 50 degrees to 62 in the space of five minutes? (12:20 - 12:25)

    P.

  10. #50
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    Quote Originally Posted by paulockenden View Post
    Unless I'm reading that wrong you seem to have gone from 50 degrees to 62 in the space of five minutes? (12:20 - 12:25)
    No it hasn't, but that's what the Evotouch believes due to the lack of regular updates from the CS92 during that period.

    In reality it has gone from 49.45 at 12:05 to 62.67 at 12:25 - eg it took 20 minutes to get there. 50+ degrees would have been reached just after 12:05, or possibly earlier when you consider Domoticz is only sampling every 5 minutes so may be as much as 5 minutes behind the most recent reading.

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