How turn on heating of my DHW storage tank

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hdehaseleer
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How turn on heating of my DHW storage tank

Post by hdehaseleer »

I recently had a new boiler installed. A Vaillant Ecotec Plus with a separate storage tank for sanitary water. This week the technician also placed the VR33 Opentherm module in the Vaillant, after which I also connected the OTGW module to the VR33 module. For the time being I still keep my old Multi-zone KNX thermostat that is connected to the OTGW input in on/off mode. And given the heat of the last few days, this relay has been open (off) for several days. Which according to the documentation corresponds to “stand alone mode”

1) OK: If, on my on/off thermostat, I force the heating in the kitchen to a high value, the thermostat kicks in and the Vaillant starts to burn. And the radiator in the kitchen gets hot. See the image of OTMonitor in the attachment OTMonitor1.jpg.

2) KO: the Vaillant boiler no longer heats the sanitary water of the separate storage tank since the VR33 module and the OTGW were connected.

3) KO: I have written a small program in Home Assistant that monitors the temperature of the storage tank and, when too low, sets the value “set_hot_water_setpoint” to 45°C and turns “set_hot_water_ovrd” to 1.
On the image otmonitor2.jpg, you see that OTMonitor has received both values. But the Vaillant does not start heating.

My questions:
1) What do I have to do so that the Vaillant boiler starts heating the storage tank?
2) I prefer that the Vaillant heats the Storage tank autonomously, so without the help of my program in Home Assistant. How can this be done? I’ve tried to put the OTGW in “monitor mode”. But then Home Assistant switch every value, each 5 seconds, between “unavailabe” and the correct value.
3) In the images of otmonitor, the value “DHW temperature” remains empty. What is the object that I should read to obtain the temperature of the hot water in my separate DHW storage tank.
Attachments
OTMonitor2.jpg
OTMonitor2.jpg (40.72 KiB) Viewed 1988 times
OTMonitor1.jpg
OTMonitor1.jpg (64.22 KiB) Viewed 1988 times
hvxl
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Re: How turn on heating of my DHW storage tank

Post by hvxl »

  1. Normally a boiler can be configured in 3 modes (nomenclature may vary):
    1. ECO mode: The storage tank is never heated
    2. COMFORT mode: Water in the storage tank is always kept at temperature
    3. SMART mode: The thermostat controls when the storage tank is heated
    The OTGW can only influence what happens if the boiler is configured for SMART mode. In that case the HW command (which I presume is mapped to "set_hot_water_ovrd" in Home Assistant) would be the method to do that. Your test seems to indicate that this doesn't happen with your boiler in combination with the external storage tank. Your guess is as good as mine as to why not.
  2. To have your boiler heat the tank autonomously, either set it to COMFORT mode, or for SMART mode just issue HW=1 once and don't touch it after that. Of course that only works once point #1 has been solved.
  3. Unfortunately you didn't provide any log. But if the value remains empty, rather than showing ???, it probably means that your thermostat doesn't request the information. The equipent matrix seems to suggest that a Vaillant Ecotec Plus supports MsgID 26 (DHW temperature). So you can request the OTGW to get that information for you, using the AA=26 command. You only have to perform that command once and the OTGW will repeatedly obtain the information.
    Schelte
    kluns
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    Re: How turn on heating of my DHW storage tank

    Post by kluns »

    Sorry, I missed your answer.

    In the meantime, I figured it out.
    Indeed, after setting the value “otgw_dhw_ovrd_gateway_cv “ (= override dhw) in HA to 1 (= enabled), my Vaillant started immediately with the heating of my separated storage tank. Even without changing the “DHW setpoint” which remained on -0,0°C. And my Vaillant now heats the storage tank autonomously (without HA)

    But the OTGW still does not give me the temperature of my separate Vaillant storage tank.
    As you suggested, I've set the command AA=26. OTmonitor immediately changes "DHW temperature" from empty to ???. But even after 30 minutes, it remains to "???".
    PS: As I indicated, my KNX/EIB multiroom thermostat is connected to the OTGW in "relay on-off". So my thermostat is not able to request the "DHW temperature" from the OTGW.
    kluns
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    Re: How turn on heating of my DHW storage tank

    Post by kluns »

    Some additional information.

    The matrix shows the values for Vaillant Ecotec Plus CW. I have a Vaillant Ecotec Plus Solo. Solo means external DHW tank.
    The types with a suffix CW are types without a DHW tank. The boiler starts only with heating the water when you open a "warm water tap" in your home.
    hvxl
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    Re: How turn on heating of my DHW storage tank

    Post by hvxl »

    Either you are following up to a thread as if you are the original poster when you're not, or you changed user names. In any case it's confusing. Spreading information over two threads also doesn't help. Making it difficult for people to understand the situation isn't generally the best strategy when looking for help.

    My impression is that your boiler doesn't support many of the messages you are looking for. When "DHW temperature" is reported as "???", that probably means that the boiler responded to a Msg26 request with Unk-DataID. When a message isn't supported, waiting 30 minutes isn't going to change that. The boiler probably also doesn't support changing the DHW setpoint via Opentherm. But that is just a guess. As I have indicated many times before, even in this thread, logs are the best way to understand what is going on. As you didn't provide one, guessing is all I can do.
    Schelte
    kluns
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    Re: How turn on heating of my DHW storage tank

    Post by kluns »

    Thanks for your answer.

    Sorry that I was confusing by using another name. I’m new on the forum.

    Indeed, my Vaillant answered with “unk-DataId” on command AA=26 (see log below).
    So the OTGW does not receive the DHW temp from my Vaillant.
    But I’ve added an additional sensor on top of my separate DHW storage tank. And now I know the DHW temp.

    I’m trying to understand how the OTGW functions for the DHW. I don’ find anything in the documentation.

    1) When starting with a new OTGW (= default values), my DHW had dropped to a very low temperature.
    But after setting the value “otgw_dhw_ovrd_gateway_cv “ (= override dhw) to 1 (= enabled) within HA (which is the same as the HW command in OTmonitor) the DHW temperature of my separate storage tank was immediately going up. Even with the “DHW setpoint” showing -0,0°C

    2) I can change the setpoint from within HA, (via the service “set_hot_water_setpoint”) and OTmonitor shows immediately the new DHW setpoint.
    But increasing the DHW setpoint from 48 to 60°C is not enough for starting the heating of the DHW. Is an additional command necessary?

    3) For your information, I uploaded a “capability log”. It’s for a Vaillant Ecotec plus Solo with the openTherm VR33 module inserted (Solo means separate storage tank)

    16:54:42.996275 Command: AA=26
    16:54:43.025475 AA: 26
    16:54:43.188838 R00000300 Read-Data Status: 00000011 00000000
    16:54:43.307965 BC000030A Read-Ack Status: 00000011 00001010
    16:54:44.184765 R80190000 Read-Data Boiler water temperature: 0.00
    16:54:44.306316 B40193B80 Read-Ack Boiler water temperature: 59.50
    16:54:44.509752 PR: I=00
    16:54:45.187379 R10014B00 Write-Data Control setpoint: 75.00
    16:54:45.304345 BD0014B00 Write-Ack Control setpoint: 75.00
    16:54:46.184312 R80380000 Read-Data DHW setpoint: 0.00
    16:54:46.305493 BC0383200 Read-Ack DHW setpoint: 50.00
    16:54:47.179790 R801A0000 Read-Data DHW temperature: 0.00
    16:54:47.300041 B701A0000 Unk-DataId DHW temperature: 0.00
    16:54:48.175226 R801A0000 Read-Data DHW temperature: 0.00
    16:54:48.295745 B701A0000 Unk-DataId DHW temperature: 0.00
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    capslog39027.gz
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    hvxl
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    Re: How turn on heating of my DHW storage tank

    Post by hvxl »

    Your log shows that the valid range for the DHW setpoint of your boiler is 35 to 70 degrees. -0.0°C is not within that range, so that reading is probably incorrect.

    The thermostat (or gateway) can indicate to the boiler whether it wants to have preheated hot water available (DHW enable = true) and at which temperature (DHW setpoint). It is up to the boiler how it handles that request. Boilers will allow for some temperature swing around the DHW setpoint. They may also implement a minimum off time or other constraints.

    A thermostat should only use the DHW enable bit to indicate when water should be preheated and when not. It must not use the DHW setpoint for this purpose.
    Schelte
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