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Thread: EvoHome Beta 02.00.19.31 - HW Priority Setting

  1. #11
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    Quote Originally Posted by DBMandrake View Post
    Whoa a second. So this new hot water priority cannot be turned off ???! Please tell me this isn't true.

    What is the reason for that ? It's definitely not appropriate to my system with a slow heating cylinder - I do not want hot water priority, and I actually even have an ABV in series with the indirect loop for the cylinder (to prevent it dropping the radiator differential pressure to zero) precisely so radiators and hot water reheat can work in parallel, and this works well for me.

    If this new feature can't be disabled this is a big step backwards for me and anyone else will a slow reheat cylinder.
    Been trying to tell them that.......but it was a decision made by the 'sales' team. Needs to be made for On/Off. The amount of systems it'll not suit....well I could go on. Many systems i've done it'll just not work on or isn't required.

    I've voiced my concerns though, I suggest others do the same.

    But in summary - No you can't turn it off if you've got a Heating valve - So two 2 ports or a 3 port valve.

  2. #12
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    yup agree, forcing the option makes all S plans operate as Y plans.

  3. #13
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    Quote Originally Posted by top brake View Post
    Only applies if you have a 'HEATING VALVE' at system layer.

    Simply, when there is a hot water demand the Heating BDR will be de-energised.

    This effectively turns an S Plan into an X Plan, and a Y Plan into a W Plan - with no changes to the hydronics or valves. Neat!
    Is this also supposed to turn off UFH zones via HCC80R? If so, I am not seeing it on my setup, as the UFH zones lights are still on.

  4. #14
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    Quote Originally Posted by mtmcgavock View Post
    Been trying to tell them that.......but it was a decision made by the 'sales' team. Needs to be made for On/Off. The amount of systems it'll not suit....well I could go on. Many systems i've done it'll just not work on or isn't required.

    I've voiced my concerns though, I suggest others do the same.
    In the official beta firmware thread ?

  5. #15
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    Quote Originally Posted by top brake View Post
    Only applies if you have a 'HEATING VALVE' at system layer.

    Simply, when there is a hot water demand the Heating BDR will be de-energised.

    This effectively turns an S Plan into an X Plan, and a Y Plan into a W Plan - with no changes to the hydronics or valves. Neat!
    Not neat if you have a system with a slow heating cylinder where you deliberately do not want hot water priority.

    Please make hot water priority an on/off setting in the installer menu. It simply isn't a good idea for this to be enabled on all systems without a way of turning it off, and it is a significant change in behaviour to previous firmwares that is going to catch some people out even if it was on by default with a way to turn it off, let alone no way to turn it off.

    Really it should be off by default after a firmware upgrade (for minimum end user surprise) with the ability to turn it on if it's applicable to the system and wanted by the owner or installer.
    Last edited by DBMandrake; 3rd April 2020 at 06:24 PM.

  6. #16
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    Quote Originally Posted by DBMandrake View Post
    In the official beta firmware thread ?
    Direct to Andy The Minion via email. I suggest you PM him, as I think it's ludicrous you can't turn it off.

    I'm going to get a lot of phone calls when this update officially rolls out

  7. #17
    Automated Home Sr Member Andy the Minion's Avatar
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    Quote Originally Posted by DBMandrake View Post
    Whoa a second. So this new hot water priority cannot be turned off ???! Please tell me this isn't true.

    What is the reason for that ? It's definitely not appropriate to my system with a slow heating cylinder - I do not want hot water priority, and I actually even have an ABV in series with the indirect loop for the cylinder (to prevent it dropping the radiator differential pressure to zero) precisely so radiators and hot water reheat can work in parallel, and this works well for me.

    If this new feature can't be disabled this is a big step backwards for me and anyone else will a slow reheat cylinder.
    DB, I am concerned by this. What the effect been on your system been please? Could you pm me and let me know your MAC address and I will put the system on trace to look at the hot water performance before and afterwards

  8. #18
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    Quote Originally Posted by Andy the Minion View Post
    DB, I am concerned by this. What the effect been on your system been please? Could you pm me and let me know your MAC address and I will put the system on trace to look at the hot water performance before and afterwards
    Hi Andy,

    I registered for the firmware update on Thursday night but haven't actually received the update yet. So I don't actually have any measured effects to report. (I'll PM my MAC address anyway - because I have authorised the monitoring even though I don't have the update yet)

    However I know exactly what hot water priority would do without even testing it - my system has a "slow" hot water cylinder that takes about 30 minutes to reheat from fully used and as a result I've designed the system to allow simultaneous hot water reheat and heating to radiators, so I'm naturally quite concerned about a software update that takes that ability of simultaneous heating and hot water reheat away from me and does not even give me an option to turn off priority to restore original behaviour.

    An example of where this would be a problem would be if we started to run a bath and then a few minutes later turned up the bathroom radiator - a fairly common situation.

    The measured cylinder temperature would drop to the reheat trigger point after running the bath for just a few minutes, (long before the bath was finished running) and as soon as that happened the heating zone valve would close and no heat would be available for radiators, so that turned up radiator which didn't get turned up until after the zone valve closed would remain completely cold for over 30 minutes that it took for the bath to finish running and the reheat to continue to completion.

    As well as that all the radiators in the house would largely cool down in that 30+ minutes causing the rooms to undershoot significantly in the winter, probably followed by an overshoot as the HR92's tried to over compensate while they were denied hot water.

    I'd not be happy with that and I suspect I'll get complaints from my other half about the radiator in the bathroom not heating up with a bath is run.

    Hot water priority is fine for a system with a cylinder reheat time <10 minutes, and if the owner/installer decides that priority is right for them and their system, but it seems very short sighted to force it on everyone, including systems where it's not appropriate without any way to turn it off.

    It also violates the "principle of least surprise", where a (later general release) software update that an end user didn't ask for, didn't know was coming, and can't refuse makes a fairly major change to the behaviour of their heating system, which when they discover it, can't be changed back as it's impossible to roll back the firmware or turn off the feature.

    In my opinion the hot water priority feature needs to have an on/off configuration setting in the installer menu and needs to default to off during the firmware update process (and perhaps during a factory reset) to not violate the principle of least surprise... It can't be that hard to add an on off preference setting surely ?

    Anyway hopefully the engineers working on this beta release can take this as constructive critisism. I'm still looking forward to testing the beta release, in particular the load scaling feature.
    Last edited by DBMandrake; 3rd April 2020 at 11:35 PM. Reason: fixed some mistakes

  9. #19
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    Quote Originally Posted by DBMandrake View Post
    Hi Andy,

    I registered for the firmware update on Thursday night but haven't actually received the update yet. So I don't actually have any measured effects to report. (I'll PM my MAC address anyway - because I have authorised the monitoring even though I don't have the update yet)

    However I know exactly what hot water priority would do without even testing it - my system has a "slow" hot water cylinder that takes about 30 minutes to reheat from fully used and as a result I've designed the system to allow simultaneous hot water reheat and heating to radiators, so I'm naturally quite concerned about a software update that takes that ability of simultaneous heating and hot water reheat away from me and does not even give me an option to turn off priority to restore original behaviour.

    An example of where this would be a problem would be if we started to run a bath and then a few minutes later turned up the bathroom radiator - a fairly common situation.

    The measured cylinder temperature would drop to the reheat trigger point after running the bath for only just a few minutes, (long before running the bath was finished running) and as soon as that happened the hot water zone valve would close and no heat would be available for radiators, so that turned up radiator which didn't get turned up until after the zone valve closed would remain completely cold for over 30 minutes that it took for the bath to finish running and the reheat to continue to completion.

    As well as that all the radiators in the house would largely cool down in that 30+ minutes causing the rooms to undershoot significantly in the winter, probably followed by an overshoot as the HR92's tried to over compensate while they were denied hot water.

    I'd not be happy with that and I suspect I'll get complaints from my other half about the radiator in the bathroom not heating up with a bath is run.

    Hot water priority is fine for a system with a cylinder reheat time <10 minutes, and if the owner/installer decides that priority is right for them and their system, but it seems very short sighted to force it on everyone, including systems where it's not appropriate without any way to turn it off.

    It also violates the "principle of least surprise", where a (later general release) software update that an end user didn't ask for, didn't know was coming, and can't refuse makes a fairly major change to the behaviour of their heating system, which when they discover it, can't be changed back as it's impossible to roll back the firmware or turn off the feature.

    In my opinion the hot water priority feature needs to have an on/off configuration setting in the installer menu and needs to default to off during the firmware update process (and perhaps during a factory reset) to not violate the principle of least surprise... It can't be that hard to add an on off preference setting surely ?

    Anyway hopefully the engineers working on this beta release can take this as constructive critisism. I'm still looking forward to testing the beta release, in particular the load scaling feature.
    Couldnt have put it better myself.

    I hope Andy you can see my concern now that this feature needs to be something that could be turned on or off. Not every system is suited for HW Priority, especially when certain systems maybe older or not designed that way.

  10. #20
    Automated Home Sr Member Andy the Minion's Avatar
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    Quote Originally Posted by DBMandrake View Post
    Hi Andy,

    I registered for the firmware update on Thursday night but haven't actually received the update yet. So I don't actually have any measured effects to report. (I'll PM my MAC address anyway - because I have authorised the monitoring even though I don't have the update yet)

    However I know exactly what hot water priority would do without even testing it - my system has a "slow" hot water cylinder that takes about 30 minutes to reheat from fully used and as a result I've designed the system to allow simultaneous hot water reheat and heating to radiators, so I'm naturally quite concerned about a software update that takes that ability of simultaneous heating and hot water reheat away from me and does not even give me an option to turn off priority to restore original behaviour.

    An example of where this would be a problem would be if we started to run a bath and then a few minutes later turned up the bathroom radiator - a fairly common situation.

    The measured cylinder temperature would drop to the reheat trigger point after running the bath for just a few minutes, (long before the bath was finished running) and as soon as that happened the heating zone valve would close and no heat would be available for radiators, so that turned up radiator which didn't get turned up until after the zone valve closed would remain completely cold for over 30 minutes that it took for the bath to finish running and the reheat to continue to completion.

    As well as that all the radiators in the house would largely cool down in that 30+ minutes causing the rooms to undershoot significantly in the winter, probably followed by an overshoot as the HR92's tried to over compensate while they were denied hot water.

    I'd not be happy with that and I suspect I'll get complaints from my other half about the radiator in the bathroom not heating up with a bath is run.

    Hot water priority is fine for a system with a cylinder reheat time <10 minutes, and if the owner/installer decides that priority is right for them and their system, but it seems very short sighted to force it on everyone, including systems where it's not appropriate without any way to turn it off.

    It also violates the "principle of least surprise", where a (later general release) software update that an end user didn't ask for, didn't know was coming, and can't refuse makes a fairly major change to the behaviour of their heating system, which when they discover it, can't be changed back as it's impossible to roll back the firmware or turn off the feature.

    In my opinion the hot water priority feature needs to have an on/off configuration setting in the installer menu and needs to default to off during the firmware update process (and perhaps during a factory reset) to not violate the principle of least surprise... It can't be that hard to add an on off preference setting surely ?

    Anyway hopefully the engineers working on this beta release can take this as constructive critisism. I'm still looking forward to testing the beta release, in particular the load scaling feature.
    DB
    I really welcome your comments and especially the effort you spent making them. They are constructive, based on your experience in the profession, and the reason we released this trial on the forum. It is also why I’m am here.
    So firstly, thank you!

    In return I will try to explain some of the how or why behind the functions and what we can or can’t do. Resideo is a big company and as my user name suggests I am just a small part of the development team. The Evo system is a big part of my working life, I have had all three version one in my home, sometimes two. They will have to take it from my cold dead hands if they ever want it back again
    So….. I will certainly accept the criticism on behalf of the team. I will try to explain where I can and not come over as defensive, but some things are outside my power to change.
    If the forum can accept that position, I would greatly appreciate you allowing me to participate.
    I will probably repeat this screed in the release feed as not everybody is following both.

    To start, the first part of what follows won’t address the main points of your comments but I would like to explain the reasons for DHW priority.

    Firstly we received a considerable amount of pressure from OpenTherm users, the argument they made was that because the boiler water temperature calculation is a sum of all the demands. When a CH system is happy ticking along at 35C and an 80C DHW demand appears, the heating gets an unwanted jolt of hot water.
    This is not normally a huge problem (an annoyance, yes) because standard tanks recover in 10-15 minutes (usually its a top up rather than heating from the cold inlet temperature) and they can sometimes recover almost as fast as they fall.
    However, for the slow cylinder being described, this is a considerable problem. The CH gets overheated for as long as the tank takes to recover.
    This is the exact opposite of the argument against DHW priority. It was the opentherm guys that noticed this, but it is also completely true for all TPI systems as well.
    An excessively long 100% demand caused by the cylinder will cause overshoots in the central heating. The time constants in room temperature control makes it impossible for even a HR92 to stop the overshoot because the hot water is already in the radiator by the time it notices it. We now have a lot of evidence to back this up because of remote diagnostics.

    The second reason is that we are heading into a world where 3 or 6kW heatpumps and 35C flow temperatures will become the norm. The Dutch are already there and in 2025 we won’t have the option of a big ass combi either. This is just about okay for a correctly insulated underfloor system in new build, but I know from helpdesk calls and site visits that heatpumps are being installed in conversions with large radiators.
    Even in a good new build the DHW becomes really critical, 55C flow is a real struggle, CoP values plummet and they will be relying on a direct electric element as boost/backup. In this case the expensive, high CO, high temperature MUST only be put into the tank. If the CH valve were open the tank will (again) be very slow and the heating will be partially supplied by a direct element.
    It’s a personal view but if mis-selling of heatpumps becomes a big thing, zoning systems will be a potential solution to some very unhappy OTC based customers with very high bills.

    The final reasons is cooling, European heatpump installers are selling them with a ‘free cooling’ sales pitch, and a non heat/cooling control will just not be acceptable. The current UK regulations exclude this from any rebates but we needed to cover this immediately. Heatpumps are two pipe systems, they can either heat or cool so again a DHW demand must close the CH valve or there will be unhappy times. The system can’t allow pump overruns into the CH system either, back in the 1990’s those new-fangled Combis had enough trouble with this, and a cooling customer will simply go up the wall

    I know this didn’t answer the ‘why no option’ point, but this was a rational decision made with the application experts in UK sales as @mtmcgavock mentioned, and it was based on technical knowledge, a balance of probabilities and experienced feedback.

    1. We made DHW priority conditional on having a CH valve, so most systems will not be DHW priority. We were actually expecting this to be picked up as a problem as it needs additional components, wiring etc in the system (short pause as the OT guys rush to the keyboard)
    The CH valve is needed because not all systems are fully HR92 and the constant opening and closing of all the HR92 will bring its own problems.

    2. The argument about underheating of the central heating with a slow cylinder. This is a 50/50 call, it is either going to be central heating overheating or underheating depending if there is priority or non-priority DHW.
    Normal cylinders just won’t notice and will work equally well with either system.

    3. We also made a call based on knowledge of the response times in central heating systems.
    a. Water is fast compared to air, a stratification layer in a tank means seconds between hot and cold water, plus the Evo has an adjustable differential so a cylinder doesn’t have to fall 15C before a demand starts like old bimetal cylinder stats.
    b. Temperature fall in a room is generally in the order of 0.2 – 0.7C/hour if there is truly no heating – and a bath of 45C water is definitely not ‘no heating’, the room will overshoot. The water in the radiator will also need to cool before room cooling starts.
    The human body cannot detect temperature changes much below 1C so the system has over an hour to respond.
    c. Finally, most cylinders do actually recover well, and because of the high flow temperature in DHW only mode this will get getter still. Importantly the slower ones will also improve because the boiler doesn’t have to drag the whole system volume up to 80C

    So having said all this, I am not closing the topic down. If we can get evidence of a significant population of Evo system that have been noticeably adversely affected, we will look to see how it can be addressed.
    Resideo employee. Comments are personal, and likely to get a hard stare from Rameses

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