Page 3 of 18 FirstFirst 1234567813 ... LastLast
Results 21 to 30 of 172

Thread: Evohome - poor temperature regulation

  1. #21
    Automated Home Jr Member
    Join Date
    Mar 2015
    Posts
    33

    Default

    Quote Originally Posted by Rameses View Post
    greyhound1234 - Firstly - when you say zone valve - do you mean Hr92 on the radiator? If so then how do you know this is open?

    There is no way the Hr92 will call for heat unless your at set point (and been falling) or below) - it will then 'trickle' the water in to attempt to control the temp of the rad (at 17 degree) - are you saying that the radiator (zone b) is on and warm (and I mean was not getting hot water)? Or are you just looking at the room temp?

    Is Zone A linked to Zone B? (next door? linking room? etc)
    Hi

    Yes HR92 valves.
    I can tell when they are open, as the water flow is noisy in the valve (particularly when they are slightly open, it is clear to hear). They do close fully, but only at Tset+ 1.5 degrees.

    "There is no way the Hr92 will call for heat unless your at set point (and been falling) or below)"
    I don't think the HR92's make that decision. As is my understanding, they just report temperature to the controller. The controller then decides when to call for heat, and instructs the valve to open or close a bit.
    Your statement also seems contradictory with that you said before, about a 1.5 degree overshoot being normal.
    As stated previously, heat is not initially called in a zone until it is at the set point and falling, but once called, it continues to be pulsed up to Tset + 1.5 degrees. i.e. heat calls are made continuously and repeatedly until 1.5 degrees over set point. This is the undesirable behaviour we have been discussing.

    "saying that the radiator (zone b) is on and warm (and I mean was not getting hot water)? "
    No I mean it gets flowing hot water!
    - No HR92 radiator valve closes down fully until a zone is 1.5 degrees higher than their set point. This is the same 1.5 degrees that the controller calls heat up to, probably not a coincidence.
    - This means that when 1 zone calls for heat, other zones that are nicely at the set point and don't need heat will still receive new hot water to their radiators, until they 1.5 degrees over and their valves close.
    Let me know if this is not clear.

    If you are all using the same firmware, this should be easily reproducible.

  2. #22
    Automated Home Guru
    Join Date
    Feb 2015
    Location
    Netherlands, the
    Posts
    244

    Default

    It should be easily reproducable indeed and it is! Except at Honeywell labs for some reason??? :S

    Just to clarify: we're discussing 2 seperate issues:

    1: the HR92 (or Evotouch), after calling for heat because of being below setpoint, keeps requesting heat from the boiler through the BDR91 for 1 minute every 10 minutes, even when the zone temperature is already way above setpoint and still rising.

    As greyhound puts it is:
    heat is not initially called in a zone until it is at the set point and falling, but once called, it continues to be pulsed up to Tset + 1.5 degrees. i.e. heat calls are made continuously and repeatedly until 1.5 degrees over set point.
    2: the HR92 doesn't close untill the room temperature is 1.5 above setpoint. Even when the HR92 is not requesting heat, the room will still heat up to 1.5 above setpoint if ANOTHER zone is heating up.
    Last edited by erik; 13th March 2015 at 11:21 AM.

  3. #23

    Default

    Quote Originally Posted by greyhound1234 View Post
    Hi

    Yes HR92 valves.
    I can tell when they are open, as the water flow is noisy in the valve (particularly when they are slightly open, it is clear to hear). They do close fully, but only at Tset+ 1.5 degrees.

    "There is no way the Hr92 will call for heat unless your at set point (and been falling) or below)"
    I don't think the HR92's make that decision. As is my understanding, they just report temperature to the controller. The controller then decides when to call for heat, and instructs the valve to open or close a bit.
    Your statement also seems contradictory with that you said before, about a 1.5 degree overshoot being normal.
    As stated previously, heat is not initially called in a zone until it is at the set point and falling, but once called, it continues to be pulsed up to Tset + 1.5 degrees. i.e. heat calls are made continuously and repeatedly until 1.5 degrees over set point. This is the undesirable behaviour we have been discussing.

    "saying that the radiator (zone b) is on and warm (and I mean was not getting hot water)? "
    No I mean it gets flowing hot water!
    - No HR92 radiator valve closes down fully until a zone is 1.5 degrees higher than their set point. This is the same 1.5 degrees that the controller calls heat up to, probably not a coincidence.
    - This means that when 1 zone calls for heat, other zones that are nicely at the set point and don't need heat will still receive new hot water to their radiators, until they 1.5 degrees over and their valves close.
    Let me know if this is not clear.

    If you are all using the same firmware, this should be easily reproducible.
    Is Zone A linked to Zone B? (next door? linking room? etc)
    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

  4. #24
    Automated Home Jr Member
    Join Date
    Mar 2015
    Posts
    33

    Default

    Quote Originally Posted by Rameses View Post
    Is Zone A linked to Zone B? (next door? linking room? etc)
    No, one is an upstairs room and one is downstairs.
    It is not heat transfer I am talking about. I am not talking about just the temperature increasing. I am saying that since radiator valves do not close until 1.5 degrees past the set point, other zones radiators will naturally run hot when any zone calls for heat.

  5. #25
    Automated Home Jr Member
    Join Date
    Mar 2015
    Posts
    33

    Default

    Or to put in really simply.
    Zone A at the right temperature, radiator cold. Zone B at the right temperature, radiator cold.
    Zone A is ramped up in temperature. Zone A calls for heat. Zone B does not. But both radiators get hot. Zone A runs until Zone A set point + 1.5 degrees. Zone B runs until Zone B set point + 1.5 degrees.

  6. #26
    Automated Home Legend top brake's Avatar
    Join Date
    Feb 2015
    Location
    the edge of the cloud
    Posts
    827

    Default

    Quote Originally Posted by greyhound1234 View Post
    Or to put in really simply.
    Zone A at the right temperature, radiator cold. Zone B at the right temperature, radiator cold.
    Zone A is ramped up in temperature. Zone A calls for heat. Zone B does not. But both radiators get hot. Zone A runs until Zone A set point + 1.5 degrees. Zone B runs until Zone B set point + 1.5 degrees.
    sounds very much like the TRV are not physically closing fully...

    what TRV bodies do you have?
    Are you sure that when the HR92 is closed that there is no flow through the radiator?
    I work for Resideo, posts are personal and my own views.

  7. #27
    Automated Home Jr Member
    Join Date
    Mar 2015
    Posts
    33

    Default

    Quote Originally Posted by top brake View Post
    sounds very much like the TRV are not physically closing fully...

    what TRV bodies do you have?
    Are you sure that when the HR92 is closed that there is no flow through the radiator?
    They are Honeywell VT117 bodies.
    They definitely do close fully, but only when the Evohome tells the HR92 to close them fully!
    I can get zones to heat completely independently and the other radiator stay cold - providing the other zone is more than 1.5 degrees above it's set point. If not, then the valve will be at least partially open.

    This is the same 1.5 degree offset that the Evohome controller is using in heat demand also. This can't be a coincidence. If I was to take a punt, I would say there will be a hard coded number in the algorithm, it should read '0.5' but someone made a typo and did 1.5.

    Anyway hopefully the symptoms are clear now.

    To summarise.

    Zone valves are not instructed to fully close until temperature is 1.5 degrees over the set point. This leads to overshoots on all zones when heat demand is called.
    Zones will first call for heat when they are at or less than the set point. But once called, zone will continue to call for heat all the way up to 1.5 degrees over the set point.
    If this '1.5' was '0.5', this would be acceptable/expected.

  8. #28
    Automated Home Guru
    Join Date
    Feb 2015
    Location
    Netherlands, the
    Posts
    244

    Default

    Quote Originally Posted by top brake View Post
    sounds very much like the TRV are not physically closing fully...
    That's exactly what he's saying. The TRV's are not closing fully. Only when the zone finally reaches a temperature of setpoint + 1.5, then they close fully. The same thing happens here, on Honeywell bodies as well.

    If Honeywell would take 15 minutes to actually test the behavior of a HR92, you would see exactly the same thing. Or are you saying this is not normal behavior, top brake? Do your tests show other results?
    Last edited by erik; 13th March 2015 at 12:49 PM.

  9. #29
    Automated Home Legend top brake's Avatar
    Join Date
    Feb 2015
    Location
    the edge of the cloud
    Posts
    827

    Default

    Quote Originally Posted by greyhound1234 View Post
    They are Honeywell VT117 bodies.
    They definitely do close fully, but only when the Evohome tells the HR92 to close them fully!
    I can get zones to heat completely independently and the other radiator stay cold - providing the other zone is more than 1.5 degrees above it's set point. If not, then the valve will be at least partially open.

    This is the same 1.5 degree offset that the Evohome controller is using in heat demand also. This can't be a coincidence. If I was to take a punt, I would say there will be a hard coded number in the algorithm, it should read '0.5' but someone made a typo and did 1.5.

    Anyway hopefully the symptoms are clear now.

    To summarise.

    Zone valves are not instructed to fully close until temperature is 1.5 degrees over the set point. This leads to overshoots on all zones when heat demand is called.
    Zones will first call for heat when they are at or less than the set point. But once called, zone will continue to call for heat all the way up to 1.5 degrees over the set point.
    If this '1.5' was '0.5', this would be acceptable/expected.
    are the adaptors are seated correctly and black wheel fully anticlockwise then the HR92 attached and switch clicked into place?
    gone through CYCL optimisation?

    if you short press the button on HR92 does it display zone B name?

    did you encounter any issues when binding?
    I work for Resideo, posts are personal and my own views.

  10. #30
    Automated Home Guru
    Join Date
    Feb 2015
    Location
    Netherlands, the
    Posts
    244

    Default

    Is there a point after 1000 questions where Honeywell will finally say: ok, seems like the system has mistakes in it. We will look at it and try to fix it.

    Or will Honeywell keep believing the system is perfect and that every problem must be a user mistake, no matter what?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •