Evohome firmware 02.00.19.31 Beta Trial - Exclusive for Automated Home Members

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18th August 2020, 10:52 AM
Andy the Minion

Quote:

Originally Posted by SteveP

That's great news :)

Hey! Not for me it isnt! :(
18th August 2020, 11:37 AM
SteveP

Quote:

Originally Posted by Andy the Minion

Hey! Not for me it isnt! :(

lol - I meant that it was great news that the increments are 0.5 :)
18th August 2020, 12:07 PM
Andy the Minion

Quote:

Originally Posted by clivesanders

Thanks ally153, I had not considered that. It explains exactly what has been happening as sometimes my loop instigates and completes a DHW heating cycle without the BDR ever being called on or off! I have set the cycle time to 12 per hour as you suggest and switched the DHW to BDR91 control. Fortunately I installed a switch so it’s easy to go back to conventional control. It will be easy to see what happens as I am logging all Evohome and relevant opentherm parameters.

Sincerely appreciate your response and will report back after it’s run for 24hrs.

Clive, I see you suspect the BDR91 response but can I also check the basics as well please? Where is your sensor on the tank, is it the surface mounted version and how high on the tank is it? If not where is the insertion pocket (a pic on pm might help)? The sensors are very fast, and the CS92 adjusts its transmit rate depending how close it is to setpoint and has a time constant of a second so we think the system is capapable of catching fast cyclinders. An obvious question but is the copper full exposed and the sensor in good contact with the tank side, also is this a standard indirect cylinder or is it direct fed?
Ally will send you a pm asking for your MAC address so we can look at the BDR/Evo response.
Regards AtM
18th August 2020, 01:38 PM
DBMandrake

Quote:

Originally Posted by clivesanders

Ally153, I set the cycle time to 12/hr as you suggested and whilst it appears to be a little better the loop is still not responsive enough for the fast recovery cylinder.

The call from the Evo controller to the BDR91 seems to be in a running in a time scheduled loop rather than being directly linked to the Cylinder measured value moving above or below the hysteresis window. So, even with a 12/hr cycle rate there could still be a significant delay in the BDR91 operating the valves to switch from CH to DHW and vice versa. Meanwhile the opentherm calls to fire the boiler seem to work in sync with the signal from the CS92. The end result is that the OT signal calls for and fires the boiler up to the DHW setpoint and the heated water is dumped into the CH bypass radiator until the BDR91 catches up and redirects the Flow to the cylinder. I think if you want the system to work in priority HW mode some attention needs to be given to this loop as with a high recovery cylinder the DHW control is not really fit for purpose. I hope this helps and I’m happy to take part in any further beta tests if it is of use. I have used Evohome for many years and am generally delighted with it but would really like to move the DHW loop fully back into it.

Are you sure you have the hot water relay bound correctly to the right function ?

There is no TPI cycle for the hot water relay, it is either 100% on when hot water needs to reheat, or 0% on when it doesn't. No in between or regular cycling.

So when the hot water temperature drops below the hysteresis window it will switch on continuously until the temperature goes above the hysteresis window.

AFAIK it doesn't matter whether you use OpenTherm or a relay for boiler control.
18th August 2020, 01:43 PM
clivesanders

Quote:

Originally Posted by Andy the Minion

Clive, I see you suspect the BDR91 response but can I also check the basics as well please? Where is your sensor on the tank, is it the surface mounted version and how high on the tank is it? If not where is the insertion pocket (a pic on pm might help)? The sensors are very fast, and the CS92 adjusts its transmit rate depending how close it is to setpoint and has a time constant of a second so we think the system is capapable of catching fast cyclinders. An obvious question but is the copper full exposed and the sensor in good contact with the tank side, also is this a standard indirect cylinder or is it direct fed?
Ally will send you a pm asking for your MAC address so we can look at the BDR/Evo response.
Regards AtM

Hi Andy, The Problem is definitely not the CS92 as I use the reading from it in my external control. The sensor is not a surface sensor it is the pocket type and deep inside the cylinder with heat sink compound. I can’t fault the CS92 performance. FYI I use an HG180 and Domoticz to capture the Evohome data which includes the HW temperature from the CS92 and then from this trigger an external relay in place of the BDR91 to switch the CH/DHW valves it works flawlessly. As a double proof that the CS92 is Ok the Evohome Opentherm Signal fires the boiler in response to it perfectly in conjunction with my bodge it’s just the lag in the BDR91. I have an opentherm Bridge that records the OT data I also record the signal to the BDR91 via the HG180. The BDR works when it is called as I see the signal to it on the HG180.
18th August 2020, 01:55 PM
clivesanders

Quote:

Originally Posted by DBMandrake

Are you sure you have the hot water relay bound correctly to the right function ?

There is no TPI cycle for the hot water relay, it is either 100% on when hot water needs to reheat, or 0% on when it doesn't. No in between or regular cycling.

So when the hot water temperature drops below the hysteresis window it will switch on continuously until the temperature goes above the hysteresis window.

AFAIK it doesn't matter whether you use OpenTherm or a relay for boiler control.

Hi, I didn't mean to imply its a TPI its and on/off function and bound as a HW relay and works as such but with lag that causes overshoot. My cylinder heats in about five minutes and the BDR does not seem to be updated frequently enouigh by the controller.
18th August 2020, 02:13 PM
DBMandrake

Quote:

Originally Posted by clivesanders

Hi, I didn't mean to imply its a TPI its and on/off function and bound as a HW relay and works as such but with lag that causes overshoot. My cylinder heats in about five minutes and the BDR does not seem to be updated frequently enouigh by the controller.

The CS92A can have some lag (which means the reported temperature on the controller can sometimes be behind) but I have never seen any lag between the controller and the hot water relay. It updates as soon as the temperature reading on the screen changes. (Slightly before actually)

Are you sure you don't have hot water overrun enabled ?

Hot water overrun adds a delay from the time the set point is reached until the hot water relay goes off. If you set this too long you can experience temperature overshoots. On a system that heats fast I would set hot water overrun to zero.

I have a slow heating cylinder and have hot water overrun set to 1 minute to allow latent heat to be removed from the boiler heat exchanger and even then I see a 1-2C overshoot in the hot water temperature if there is no heating load to soak up the excess latent heat, as there often isn't at this time of year.

I leave it enabled to keep my boiler happy though as it is very old and a little prone to kettling if it is suddenly switched to 100% flow through the ABV at a high flow temperature.
18th August 2020, 02:37 PM
clivesanders

Quote:

Originally Posted by DBMandrake

The CS92A can have some lag (which means the reported temperature on the controller can sometimes be behind) but I have never seen any lag between the controller and the hot water relay. It updates as soon as the temperature reading on the screen changes. (Slightly before actually)

Are you sure you don't have hot water overrun enabled ?

Hot water overrun adds a delay from the time the set point is reached until the hot water relay goes off. If you set this too long you can experience temperature overshoots. On a system that heats fast I would set hot water overrun to zero.

I have a slow heating cylinder and have hot water overrun set to 1 minute to allow latent heat to be removed from the boiler heat exchanger and even then I see a 1-2C overshoot in the hot water temperature if there is no heating load to soak up the excess latent heat, as there often isn't at this time of year.

I leave it enabled to keep my boiler happy though as it is very old and a little prone to kettling if it is suddenly switched to 100% flow through the ABV at a high flow temperature.

Interesting... I certainly don't have any HW overrun set and as per my earlier remark to Andy the CS92 is fine as I use that signal myself. It does sound as if there is something amiss so it will be interesting to see what Andy/Ally see when they monitor.
18th August 2020, 04:19 PM
DerekWilliamsUK

Looks to me like my system has just updated with the latest BETA Firmware...
18th August 2020, 07:45 PM
SteveP

Quote:

Originally Posted by DerekWilliamsUK

Looks to me like my system has just updated with the latest BETA Firmware...

Yep just noticed a new thermometer over sunshine icon on one zone and checked eco and its adjustable 👍🏻😁 brill - thanks all at evohome development

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