Intergas DHW Comfort function

[rvi]

I have an Intergas Xtreme24 boiler, with Honeywell Round Modulation thermostat. It provides heating to the whole house, but hot water only for the shower.

Intergas provide a DHW ¨Comfort¨ function, which can either be ¨off¨, ¨eco¨, ¨on¨; for this discussion I will ignore the ¨eco¨ mode. When ¨on¨ the boiler keeps a small volume of water pre-heated (contents of the heat ex-changer) and hot water comes significantly faster. It also increases gas consumption But if you don´t use it you have to wait fairly long for hot water to arrive, thus wasting water.

So in the morning I have to tap on the boiler : 1x to access the menu, 2x on DHW symbol, 2x on either ¨+¨ or ¨-¨ and then 1x on ¨enter symbol¨ to turn the DHW comfort function on and after showering the same again to turn it off. That´s rather silly - would be great if this could be done from Home Assistent, but I could not find any info.

I know Intergas provides a gateway, Comfort Touch thermostat and an app. The Comfort Touch thermostat does not support on/off switching of the DHW comfort function. The app on the other hand does !

The app talks to the gateway, which is connected to the Opentherm terminals of the boiler. I therefore suspect that Intergas uses some unused MsgID to tell the boiler to switch the DHW comfort function to on, eco or off (? just guessing ?)

Since this is the only function I really want/need I was hoping this could be done via the Opentherm Gateway (without Intergas gateway and Comfort Touch thermostat), which would also allow for reading certain other values (´nice to have¨; I don´t want to control the heating myself - the Honeywell Round Modulation does fine for me : keeps things simple).

Does anybody know how Intergas (de-)activates the DHW comfort function ?

[hvxl]

Based on your description, I would have guessed that the gateway uses MsgID 99 for this. That ID can be used to set the DHW operating mode to Auto, Anti-legionella, Comfort, Reduced, Protection, or Off, if the boiler supports it. But looking at the equipment matrix, the Intergas Xtreme doesn't seem to.

According to the manual, the DHW function can be controlled by an Opentherm thermostat when you set the DHW comfort function to "eco" with parameter 74 = 0. This would be the normal control via ID0:HB1. If you set it up like that, you can control when water is preheated with the HW command of the OTGW. Run HW=1 before showering, then HW=0 afterwards (or during). Alternatively, if you send HW=P, the OTGW will attempt to do one heating cycle; get the water up to the configured temperature, then return to the previous setting. Note: I am not aware that this function is being used by many people. So let me know if it doesn't work correctly for you.

[rvi]

Great - thank you for your quick reply !

I did come across the remark in the Intergas installers manual about setting DHW to ¨eco¨ and param 74=0, allowing for an Opentherm thermostat which supports this function to switch it on and off. So I initially looked for such a thermostat and found .... none; even the Intergas Comfort Touch doesn´t support this.

I am new to Home Assistant and your OTWG, haven´t got this in place yet, so can´t try it out yet. At this point merely assessing whether or not (and how) it should be possible. Will take some time because of other priorities, but once I have tested your instructions will report back here.

About the MsgIDs : your equipment matrix list all the numbers, but is there somewhere a list of the meaning of all these MsgID numbers ?

[hvxl]

Thermostat documentation can be less than clear about this functionality. But at least several Honeywell thermostats have some support for controlling DHW. There's a Round Modulation model that has a button to manually switch the DHW enable bit. Programmable Honeywell thermostats usually don't enable DHW when set to vacation mode and during the "Sleep" stage of the program. This means that it burns gas all day long to preheat the water when you don't need it. But when you want to take a shower in the morning, there is no hot water yet. So not the most useful algorithm. Then there's the Thermosmart, which lets you choose for each heating setting if DHW should be enabled. Most flexible is the Remeha iSense, which has a complete separate schedule for DHW.

When you hover the mouse cursor over a MsgID in the equipment matrix, a tooltip pops up with a short description of the ID. If you want to know even more than that, search the internet for the Opentherm specification. It is not officially released, but at least version 2.2 can be found in several places.

[adijk]

…

The app talks to the gateway, which is connected to the Opentherm terminals of the boiler. I therefore suspect that Intergas uses some unused MsgID to tell the boiler to switch the DHW comfort function to on, eco or off (? just guessing ?)

…

I have such a gateway and the gateway is connected via RF to the boiler and the thermostat is connected via OpenTherm or RF. So the gateway can’t send any OpenTherm-messages by wire.
My best guess is that the DHW-off-function via the app through the RFgateway is sending Intergas-specific commands.

[rvi]

@Schelte:

I have tried both Brave and Firefox browsers (under Linux Mint), but I don´t get any tooltips when hovering the mouse cursor over the MsgIDs ....

I did find the Opentherm protocol spec, a.o. on Ihor Melnyk´s site, which contained all the protocol layer descriptions.... but no list of MsgIDs

On the various pages of your website there are descriptions of some of the MsgIDs, but it would be nice to have a single comprehensive list with all MsgIDs, descriptions, possible values and their meanings - haven´t found that anywhere yet.

Will look into the thermostats you mentioned - thank you.

@adijk:

You are right - it´s an RF link.

But if as Schelte suggests HW=0 and HW=1 relate to the comfort function, than that should work when setting the comfort function to ¨eco¨ and the number of ¨eco¨ days to 0 (parameter 74), effectively disabling ¨eco¨, as per Intergas manual. Intergas isn´t very clear about the eco function.

I was confused in thinking that there were 2 separate functions :
1) DHW on/off, on = hot water on demand, off = never any hot water
2) DHW Comfort on/off, on = hot water pre-heated, off = no pre-heating
but I now understand that is wrong and HW=0 resp 1 should relate to the Comfort function.

[hvxl]

I must not understand what you are looking for. The tooltip uses the HTML title attribute, which has been around since the early days of HTML. It definitely works in both Firefox and Brave on linux. I just checked again:

tooltip.png (21.77 KiB) Viewed 3161 times

The Opentherm spec on Ihor Melnyk´s site contains a list of MsgIDs in chapter 5.4, with more detailed descriptions in chapter 5.3. That spec was basically all the information I had when I created the OTGW. If that doesn't meet your needs, you will have to explain more clearly what you want.

[rvi]

You are correct; haven´t got a clue why the tool tips did not show up earlier, but they do now

I will have to go through the OpenTherm spec again (probably many times). Rather cryptic descriptions and use of terminology (e.g. try to find a DHW Comfort function - or if you like DHW pre-heat function - in that ´specification¨ ...) Respect that you were able to create the OTGW based on this spec !

I suppose it may become clearer once I have got HA + OTGW setup to play with.

[rvi]

In the mean time I have looked at the thermostats you mentioned :

- could not find the Honeywell Round Modulation with button for DHW; only the basic wired and wireless versions (I have got the wired version T87M), seems Honeywell now markets these under resideo.com,
- Thermosmart : went bankrupt 05/2023, taken over by Plugwise. Plugwise only actively markets the ¨Anna¨ wireless thermostat. Looks like the ¨Anna¨ thermostat can do it, except it is not clear whether or not you also need their ¨Adam¨ gateway and their app (but then I might as well use the Intergas gateway, ComfortTouch thermstat and app)
- Remeha iSense : yes, should indeed work; have past negative experience with Remeha´s iSense (too many errors; but this was > 5 yrs ago, so it may be better now)

I have underfloor heating / no radiators; basic Honeywell Round Modulation does fine (=simple), and I prefer wires over wireless.

So I think I may be better off in spending some more time on investigating the OTGW and Opentherm protocol, and using Home Assistant, which I want for other purposes anyway.