Page 1 of 2 12 LastLast
Results 1 to 10 of 13

Thread: Evohome not behaving as expected

  1. #1
    Automated Home Lurker
    Join Date
    Dec 2021
    Posts
    2

    Default Evohome not behaving as expected

    Hi

    I have a new installation of Evohome which I am having trouble getting to work consistently. The system is an oil fired boiler, with a ATP921R3100 Controller, a BDR91 Wireless Relay Box, a water cylinder kit and 12 HR924UKs. There are separate HW and heating motorised valves, all working fine.

    There is no problem getting the boiler to fire as required, the issue is that the TRVs don't seem to do as I thought they should. At any time, there will be a couple of rooms where the target temperature is 20 degrees, but the reported room temp is 16.5 - yet the rads don't come on, so the room gets colder and colder. In another room the target will be 20 and the rad is on full blast, reporting a room temp of 22! Yesterday I had to remove the TRV top in the kitchen, open the valve up and warm up that way, as it showed no interest in coming on even when I applied an override to 6 degrees higher than measured temperature.

    In a zone with two rads, one is coming on but the other isn't. Again, the valve bodies work fine ifs they are manually opened.

    I'm frustrated that the Evohome system comes with a really good installation manual but nothing whatsoever to explain how the system works and how to configure it for some typical home scenarios. Why, for example, does the Eco/Boost override say it offers + or - 3 degrees, but when you use it there is nowhere to make that choice and it only actually gives you the Eco - effect? Why is there only one custom setting possible? It would cost Honeywell nothing to let you store various scenarios, instead of having to change one all the time.

    Which room should I locate the controller in (does it matter?) - has it got a thermostat in it? In some places the documentation seems to suggest the controller has a master thermostat but there is no evidence to support that in the menus. Would I be better off in some rooms with a wall thermostat to control the zone TRVs rather than relying on the ones built into the TRVs?

    How does the custom setting work? If you add some rooms to it, when you apply it does it leave the unselected rooms on default setting whilst applying the custom setting to the rooms you added to it? We are a b&b so I want to be able to easily turn the guest rooms off when the government locks us down, so do I keep the custom zone for 'guest bedrooms off'and when I apply that will it leave everything else with the normal setting?

    And, most importantly, why does my heating not come on a room which is 5 degrees below the target when the rad in another room is blazing hot?!? At the moment when the house is cold it is a total ball ache to get it to warm up - compare that to my old dumb system where I just had to press a single button to get nice and toastie.

    I'm sure the system can do what I need, I'm just struggling with the lack of configuration support from the manufacturer. Any guidance would be greatly appreciated!

    Thanks

  2. #2
    Automated Home Sr Member
    Join Date
    Oct 2020
    Posts
    87

    Default

    First, are you aware that you can see the demands for each zone? Long press on settings, and then System Summary. Check that the rooms that are cold are actually calling for heat. Are you sure you have each TRV assigned to correct zone?

  3. #3
    Automated Home Guru
    Join Date
    May 2021
    Posts
    100

    Default

    I had a similar problem and had to set the HR92 to full stroke mode as it wasn't opening the valve, this was on a Drayton TRV-4 body. I've since done it on a few more TRV-4's and found things seem to work much better.

    When you did the override did you do it on the control panel or do you turn the top of the HR92? I think to start off with, do it on the HR92 itself then wait a minute to listen for the motor. If the temperature difference is greater than 1.5 degrees then the motor should open the valve all the way. You can check the valve position in the menu, I think it's option 9 (long press the button until the menu comes up then rotate to option 9 "valve pos", press button to select, then rotate the dial to "1" to enable it, press the button again and it should show you the valve position). It should show 100% - if the radiator still does not get hot then I would try full stroke mode, I can't remember which menu number this is but think it's called "stroke" - set it to "1" - this will tell the HR92 to open the valve further.

    If you are setting the override on the panel and you don't hear the motor open, or the set temp does not update on the HR92, then it's more likely to be a comms issue.

  4. #4
    Automated Home Lurker
    Join Date
    Dec 2021
    Posts
    2

    Default

    Hi and thanks for the replies - lots of helpful suggestions!

    I didn't know I could view the demands for each zone so will give that a try.

    The TRVs are definitely correctly assigned - I checked that first, in case the heads had got muddled.

    I did test all the TRVs manually, by removing the head and using the screw wheel to open and close all the valves. I thought long stroke was to compensate for unusual valves where the manual process didn't open the valve, but I will certainly give that a go as well. I have a mix or Drayton and Danfoss valves and early on discovered I hadn't mounted the Danfoss adapters correctly, so they weren't closing the valves properly, but I fixed that before this latest issue started. The ones which aren't coming on are a mix of the two, so it isn't the case that (say) Drayton ones are working but Danfoss aren't.

    I have tried both control panel overrides and on-valve ones. The controller has generally been in the room with the TRV which wasn't opening so it is hard to believe the comms is poor. I'll take a look at the valve positions the next time I have this issue.

    Anyway, thanks for the ideas and I'l report back when I have tried them out.

  5. #5
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,756

    Default

    All the settings for the Quick Actions are within its own menu, including how much you want Eco set to. But when you turn it on, it won't ask you by how much, it uses the value you set earlier.

  6. #6
    Automated Home Guru
    Join Date
    Dec 2016
    Posts
    228

    Default

    Maybe worth noting that the tips given depend on the controller type and software version, e.g. the controller I have does not have a `System Summary` menu entry and Eco is fixed to 3 degrees below the normal setting.

  7. #7
    Automated Home Lurker
    Join Date
    Dec 2020
    Posts
    9

    Default

    Did you fix this? I had similar, albeit less dramatic, issues with zones failing to come up to temperature, until I disabled Advanced Load Scaling

  8. #8
    Automated Home Legend
    Join Date
    Sep 2014
    Location
    Scotland
    Posts
    2,355

    Default

    Quote Originally Posted by bbstrikesagain View Post
    Did you fix this? I had similar, albeit less dramatic, issues with zones failing to come up to temperature, until I disabled Advanced Load Scaling
    Did you have load scaling on Normal or Partial ?

    I find Normal too aggressive, (zones struggling to make their temperatures as you report) but partial works just nicely for me and helps avoid room temperature overshoots as the schedule changes that I see with load scaling disabled.

    Also keep in mind that Load Scaling is an adaptive algorithm which adapts to every zone individually and is actually quite slow to adapt - I find it takes as much as a week for some zones to adapt to load scaling being enabled. So if you just turn it on then give up on it within a day it will not get a chance to learn the behaviour of your rooms.
    Last edited by DBMandrake; 19th January 2022 at 10:17 AM.

  9. #9
    Automated Home Lurker
    Join Date
    Dec 2020
    Posts
    9

    Default

    Quote Originally Posted by DBMandrake View Post
    Did you have load scaling on Normal or Partial ?
    Thanks for your reply.

    I had it set to NORMAL. Not sure if that was the default or if I'd set it manually. Whichever, I didn't change it for a year or more, I think I never messed since around when I got the firmware update. In winter some rooms weren't doing anything much to come up to temperature, big differentials and valves barely opening. I read of similar troubles, set it to DISABLED, and all was MUCH better, with all rooms more or less in control - though maybe 0.5C over/undershoot here and there...

    I'll try PARTIAL for a few weeks, see if that works out during coldish weather

  10. #10
    Automated Home Lurker
    Join Date
    Dec 2020
    Posts
    9

    Default

    Quote Originally Posted by DBMandrake View Post
    Also keep in mind that Load Scaling is an adaptive algorithm which adapts to every zone individually and is actually quite slow to adapt - I find it takes as much as a week for some zones to adapt to load scaling being enabled. So if you just turn it on then give up on it within a day it will not get a chance to learn the behaviour of your rooms.
    Quote Originally Posted by bbstrikesagain View Post
    I'll try PARTIAL for a few weeks, see if that works out during coldish weather
    BRRR. Nope, can't hack it, can't wait for it. Yes, only two days in, but the single scheduled (working from home) zone is a full 2.5C below target half an hour into schedule. The HR92 is at 100% but the appliance is sitting at 7% - as if that is going to touch the sides... Normally, with Optimum Start (unchanged at 2 hours max) each zone is bob on when it's supposed to be. I can't for the life of me see why Advanced Load Scaling should need me to move out while it learns its stuff. Actually, with months of learning in NORMAL it never worked properly, letting zones lag badly, and on PARTIAL, on day two, it's the same.

    Back to DISABLED and appliance duty straight to 100%. Surely that's what it should be when a zone is so far below what should be the TPI proportional band, only backing off if it learns that the zone heats too quickly and causes overshoot?

    Disclosure: as well as six HR92s controlled rads, in six zones, one sensed by the evotouch, one by a T87RF, I also have two TRV regulated towel rails that evohome knows nothing about. My logic here was thus: there are reports that HR92s fail in bathrooms, perhaps due to humidity; the HR91 or HR92 look pants IMO on a smart polished stainless towel rails; simply airing the towel rails and bathrooms whenever any zone calls the boiler seems like a pragmatic solution - looks good and works. I imagine many evohome systems have one or two loads that aren't controlled by evohome? Could the heating tapped off by the two TRVs be what scuppers Advanced Load Scaling's learning?

    I don't think that's it. It seems inexcusable to make such a low appliance demand when when a zone is so far below target, even during an adaptation phase. Surely we're not supposed to move out while the algorithm does some massive cold step response experiments? Surely it should risk a little overshoot and judiciously back off from there?

    So, Advanced Load Scaling, DISABLED again

Tags for this Thread

Posting Permissions

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