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Thread: What would you like to see in evohome? (have your say)

  1. #231
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    I've a 210 baxi stainless tank so the probe had to be installed quite low - maybe not quite a 3rd up where the cover is.

    Makes sense what you are saying about the reading dropping fast as cold water enters. I've not checked how often and for how long it reheats if always on. My thinking was if it's heated to 65 and then allowed to naturally cool to 50, it would still be safe.

  2. #232
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    Quote Originally Posted by fergie View Post
    I've a 210 baxi stainless tank so the probe had to be installed quite low - maybe not quite a 3rd up where the cover is.

    Makes sense what you are saying about the reading dropping fast as cold water enters. I've not checked how often and for how long it reheats if always on. My thinking was if it's heated to 65 and then allowed to naturally cool to 50, it would still be safe.
    Only if the whole cylinder was heated to 65 and then the whole cylinder dropped to 50 through gradual heat loss rather than water use. However if you are using the hot water the 50 reading is a combination of 65 degrees at the top and 20 degrees at the bottom with a boundary layer in between that covers 20-45 degrees. If that 20-45 degree section is allowed to sit there a long time without being heated bacteria may multiply.

    When you use some hot water causing the reading to drop the water in the top part of the cylinder isn't dropping in temperature and the system only has to reheat the new cold water that has entered at the bottom - so long as the cold patch remains significantly colder than the water at the top the heating process causes convection in only the cold part of the cylinder with the boundary to the hot section at the top acting like a "ceiling" for the convection. So it's not like the reheating process is having to reheat the entire cylinder - only the cold part.

    In a way this is all quite theoretical because I think Legionella in household hot water cylinders (as opposed to large commercial hot water systems) is exceedingly rare, but if you do get it I believe it can be quite nasty.

  3. #233
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    Legionella in the home setting usually manifests itself in the form of mild cold or flu symptoms. Of the 15 or so serogroups 1 is the worst, most people contract sero group 5-10. In the household situation using a shower (mostly likely source of an infection) every day tends to thermally flush the bacteria out, but it's not guaranteed, so water temperature should ideally be at 60C or more to help prevent growth. In an industrial environment where legionella is usually controlled by chemical cleaners, the chemicals need to be changed regularly as the bacteria eventually becomes resistant.

  4. #234
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    Quote Originally Posted by g6ejd View Post
    Legionella in the home setting usually manifests itself in the form of mild cold or flu symptoms. Of the 15 or so serogroups 1 is the worst, most people contract sero group 5-10. In the household situation using a shower (mostly likely source of an infection) every day tends to thermally flush the bacteria out, but it's not guaranteed, so water temperature should ideally be at 60C or more to help prevent growth. In an industrial environment where legionella is usually controlled by chemical cleaners, the chemicals need to be changed regularly as the bacteria eventually becomes resistant.
    I'm assuming this doesn't apply in the case of either an electric shower or a combi boiler as there is no storage of significant quantities of hot water and as soon as you run hot water from either fresh cold water is being brought through and heated on demand ? (Even though in the case of the electric shower the water never goes above about 42 degrees)

    We have an electric shower but a hot water cylinder for two sinks only, which would seem to be the worst case scenario as we don't get through a cylinder of water very quickly...

    I do make sure that the hot water is scheduled on and thus between 49-54 degrees during the day whenever the house is occupied though, even if I don't think we would need to be using the water much outside of breakfast and dinner times. For a while I was only scheduling it at times of the day when I thought we might actively use the water but thinking about legionella made me change that to having it on any time the house is occupied. (Except overnight)
    Last edited by DBMandrake; 30th May 2017 at 09:01 AM.

  5. #235
    Automated Home Legend paulockenden's Avatar
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    I seem to remember it's water being held at hot (but not hot enough) temperatures that's the problem. The tank becomes a bug farm.

  6. #236
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    Quote Originally Posted by paulockenden View Post
    I seem to remember it's water being held at hot (but not hot enough) temperatures that's the problem. The tank becomes a bug farm.
    Yes, which unfortunately is exactly what a hot water cylinder does when hot water is scheduled off. (Gradually creeps down into the danger zone and lingers there for a long time overnight or when the house is empty during a work day)

    I think if I was getting a new boiler I would switch to a combi as we really have no need for a hot water cylinder with only two sinks and a rarely used bath. (We almost always use the electric shower) The dishwasher and washing machine both also heat their own water so only need a cold supply. That solves the problem completely and probably saves money for infrequent use of hot water. The only reason we have a cylinder is that's what was already there. I just modified it to be an S-Plan system controlled by the Evotouch instead of an old gravity circulation system! Previously the hot water temperature was all over the place - either too cold or too hot depending on heating demands.
    Last edited by DBMandrake; 30th May 2017 at 09:12 AM.

  7. #237
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    Quote Originally Posted by paulockenden View Post
    I seem to remember it's water being held at hot (but not hot enough) temperatures that's the problem. The tank becomes a bug farm.
    I believe it is more to do with water collecting in bends in pipe runs where it is left standing and the bug grows. It can then come out as part of the water vapour or mist when you turn the shower on. A temperature of 60c kills the bugs. A lower temperature will do it but not too low. I think the default setting in boilers is 50c. I was advised years ago that when staying in an hotel in foreign parts before using the shower in the room to turn it full on and at maximum temperature for a minute or so to flush out the system and kill the bugs.

    Not sure how all this fits in with the original thread though!!

  8. #238
    Automated Home Legend paulockenden's Avatar
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    Has anyone added Stringify integration to the "What would you like to see?" list yet?

    I notice a couple of other Honeywell products are there, but no Evohome.

    Given how much more flexible Stringify is compared to IFTTT, it's a real pity it isn't supported.

  9. #239

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    Quote Originally Posted by paulockenden View Post
    Has anyone added Stringify integration to the "What would you like to see?" list yet?

    I notice a couple of other Honeywell products are there, but no Evohome.

    Given how much more flexible Stringify is compared to IFTTT, it's a real pity it isn't supported.
    Ill reach out - they do in US - let me come back to you
    getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own

  10. #240
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    Coming back to this thread after a while and interested to learn more about how Geofencing can be implemented using Life360. Can anyone share good/bad experiences and example scenarios?

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