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Thread: Honeywell CM Zone - basic questions

  1. #11
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    I've had my CM67z system installed for a couple of months now and am having difficulties getting it to work properly. Basically the boiler keeps cycling even when there is no call for heat from the CM67zs - even sometimes at night when the temperature setpoints are all at 10 degrees (and the house is much warmer than that). When this happens I've found that either manually switching off the HC60 or switching off the power to the HC60 for a few seconds stops it doing this but that's not exactly what you want to have to do at 2am in the morning. It also does it during the day time when the room temperatures have stabilised at whatever I've set them, this doesn't seem so odd except that the radiators more often than not stay cold and all the boiler's doing is heating itself up. I think my fuel consumption since I installed the system has actually increased by about 25%.

    I've had several conversations with Honeywell who've not really got anything to say. I've tried various settings to see if any make a difference but with no luck. My guess is that this is down to software errors but it is just a guess. has anyone else had similar expriences or knows of how to set it up properly to top this (I have two CM67zs controlling four zones. One of these has three HR80s (the hall), the rest are just one HR80 per zone. I've set the CM67z controlling the hall and living room to be the synchronisation master (I've also tried it with neither set as the SM and it seems to cycle more often)).

  2. #12
    Automated Home Sr Member NeilUK's Avatar
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    Quote Originally Posted by PeterH View Post
    I've had my CM67z system installed for a couple of months now and am having difficulties getting it to work properly. Basically the boiler keeps cycling even when there is no call for heat from the CM67zs - even sometimes at night when the temperature setpoints are all at 10 degrees (and the house is much warmer than that). When this happens I've found that either manually switching off the HC60 or switching off the power to the HC60 for a few seconds stops it doing this but that's not exactly what you want to have to do at 2am in the morning. It also does it during the day time when the room temperatures have stabilised at whatever I've set them, this doesn't seem so odd except that the radiators more often than not stay cold and all the boiler's doing is heating itself up. I think my fuel consumption since I installed the system has actually increased by about 25%.

    I've had several conversations with Honeywell who've not really got anything to say. I've tried various settings to see if any make a difference but with no luck. My guess is that this is down to software errors but it is just a guess. has anyone else had similar expriences or knows of how to set it up properly to top this (I have two CM67zs controlling four zones. One of these has three HR80s (the hall), the rest are just one HR80 per zone. I've set the CM67z controlling the hall and living room to be the synchronisation master (I've also tried it with neither set as the SM and it seems to cycle more often)).
    Is the HC60NG LED flashing? If the comms is lost any of the registered modules then it will flash the LED and I'm sure that it fails "safe" (i.e. on) if comms are lost. You could also try factory resetting the HC60NG and re-registering the CM67s to see if that helps.

  3. #13
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    Quote Originally Posted by NeilUK View Post
    direct boiler compensation would cause corrosion damage to conventional boilers leading to premature failure.
    Neil, could you explain that bit please? (Sounds like something to avoid!)

    Thanks,
    MAtt.

  4. #14
    Automated Home Sr Member NeilUK's Avatar
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    Quote Originally Posted by MattB View Post
    Neil, could you explain that bit please? (Sounds like something to avoid!)

    Thanks,
    MAtt.
    No problem :-)

    Direct boiler compensation means that the flow temperature of the water is reduced by controlling the firing of the boiler directly as opposed to using a mixing valve where the boiler runs at its usual high temperature and the water temperature is reduced by the valve mixing boiler water with cooler return water from the heating system.

    Conventional boilers are made to run at high temperatures that in turn keep the flue gas temperature above the magic condensing point hence most of the water vapour and water-permeable constituents are ejected through the flue in a fairly harmless manner (to the boiler at least). When you operate the boiler for any length of time at a cooler temperature you run the risk of condensing the flue gases and this water will also contain lots of other compounds that are very corrosive to the materials used in standard boilers - for example many older boilers use cast iron heat exchangers. These components can corrode to the point of failure very quickly if subjected to the condensate.

    In a condensing boiler the materials used are designed to resist the corrosive elements of the condensate so can generally be safely used with direct compensating weather compensation controllers. You still have to check the manufacturers datasheets though as some fuels (oil for example) may still cause excessive corrosion at lower temperatures and in these cases a minimum return temperature is specified and should be maintained when compensating the boiler.

  5. #15
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    Thanks Neil, you really know your stuff!

  6. #16
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    Quote Originally Posted by NeilUK View Post
    Is the HC60NG LED flashing? If the comms is lost any of the registered modules then it will flash the LED and I'm sure that it fails "safe" (i.e. on) if comms are lost. You could also try factory resetting the HC60NG and re-registering the CM67s to see if that helps.
    Thanks Neil. No the light's not flashing and there's no problem with comms. Re-setting the HC60 and then re-binding the CM67s is what the Honeywell technical people suggested a few weeks ago. It seemed to work for a while but has reverted back to cycling now (I just got in tonight 20 mins after the setpoint had dropped to its 12o night setting and there was the green light - the room temperature is 17o).

    The fault seems to have reverted when I had altered the room temperature sensor use parameter (6:tS) for the CM67z configured as the synchronisation master from the default (0: disabled) to (2: enabled and control). The reason for changing being that zone 1 of this CM67 controls a zone with 3 HR80s and they all seemed to behave differently so I switched to controlling them all together from the CM67.

    I guess I'll just have to reset everything again and see how I get on but would like to know if this is a known issue or if there it's something to do with getting the right parameter settings.

    Peter

  7. #17
    Automated Home Sr Member NeilUK's Avatar
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    Quote Originally Posted by PeterH View Post
    Thanks Neil. No the light's not flashing and there's no problem with comms. Re-setting the HC60 and then re-binding the CM67s is what the Honeywell technical people suggested a few weeks ago. It seemed to work for a while but has reverted back to cycling now (I just got in tonight 20 mins after the setpoint had dropped to its 12o night setting and there was the green light - the room temperature is 17o).

    The fault seems to have reverted when I had altered the room temperature sensor use parameter (6:tS) for the CM67z configured as the synchronisation master from the default (0: disabled) to (2: enabled and control). The reason for changing being that zone 1 of this CM67 controls a zone with 3 HR80s and they all seemed to behave differently so I switched to controlling them all together from the CM67.

    I guess I'll just have to reset everything again and see how I get on but would like to know if this is a known issue or if there it's something to do with getting the right parameter settings.

    Peter
    Certainly not any reported problems on any of the Honeywell technical forums.

    Have you tested the system by turning down every HR80 until they display "Off" and then waiting to see if the HC60 does switch off? The control algorithms are quite clever and use all kinds of self-learning & adaption to supposedly achieve better control than simple thermostatic switching, maybe one or more of the HR80s has got itself into a mess and this is causing the problem. You can do a factory reset on a HR80 by taking out a battery and re-inserting while holding in the binding button. You then need to re-bind it before it will start working.

    If you have optimum start enabled then the HR80s can start upto 3 hours before the entry in the time programme, could this be part of the problem overnight.

    If you set the CM67s to frost mode does the HC60 shut off?

    Finally, you could test the room sensors by blowing warm air over them from a hairdryer - they got out-of-scale as they approach 40 degrees so don't worry if you see some strange values.

  8. #18
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    Thanks Neil. I've reset the HC60 and it seems to be behaving OK now, but will try the various tricks you suggested if it happens again.

    One clarification - I turned optimisation off as it seemed to be firing up way too early (4am!), shutting down after a few minutes, then coming back on a while later but getting to the setpoint temperature a good while before needed. perhaps needs more time to self-learn but we needed to sleep!

    Can you provide the links to the HW technical forums?

    Thanks,

    Peter

  9. #19
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    Neil,

    One other question: Even during the day the boiler keeps cycling when the room temperature has been reached and all the TRVs are closed - so no heat is flowing (pipes are stone cold). Does this suggest that the HR80s are not adapting to my TRVs properly (Peglar Terrier IIs) so they think the valve is slightly open when in fact it's not. I noticed when I fitted the HR80 that although the motors activated nothing appeared on the display as the instructions indicated it should (ie "A followed by three additional characters appears in the display of the HR80"). Would be grateful for any insights.

    Peter

  10. #20
    Automated Home Sr Member NeilUK's Avatar
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    Quote Originally Posted by PeterH View Post
    Neil,

    One other question: Even during the day the boiler keeps cycling when the room temperature has been reached and all the TRVs are closed - so no heat is flowing (pipes are stone cold). Does this suggest that the HR80s are not adapting to my TRVs properly (Peglar Terrier IIs) so they think the valve is slightly open when in fact it's not. I noticed when I fitted the HR80 that although the motors activated nothing appeared on the display as the instructions indicated it should (ie "A followed by three additional characters appears in the display of the HR80"). Would be grateful for any insights.

    Peter
    If your HR80s are using version 1.X firmware (the firmware version is displayed when you press the binding button) the it could be that the automatic adaption (which aims to measure the stroke of the valve) may not be 100% successful so you could try the manual adaption technique described in the HR80 installation sheet.

    If the HR80s are V2.X then you do not have this facility but you could set the stroke to "Full" by holding the binding button until the display shows "FUL".

    If the TRV is not very linear then it could be that the HR80 thinks the valve is open at a low percentage e.g. 15% but the valve is actually still closed. This could indeed cause the cycling problem. I'll see if there is any way on a CM Zone system to find out the heating demand from the HR80. If there is I will post the info here for you.

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