documentation of ems parameters

[moritzthecat]

overall the documentation of EMS control is not sufficient to me. I think there is a missing link between supplier manuals and the parameters which could be altered in ems-esp: what is the purpose, value ranges, impact on other parameters and dependencies. To my knowledge this does not exist and could be a nice adddition to ems-esp. I would expect that the community has already knowledge about this. and this could grow over time...

[proddy]

I agree; this is much needed. Over the years, we have made several attempts to gather information from the EMS-ESP user community and store it centrally, but it has never really gained traction. Bosch, the owner of the EMS protocol, keeps the details well hidden for competitive reasons. You won’t find much in the manuals either, other than the configurable settings for the actual units, which are still quite vague. For example, there is little clarity regarding the differences between comfort modes such as Off, Hot, Auto, Eco, Eco+, etc.

The underlying philosophy seems to be that if you don’t know what the EMS entity does, you probably don’t need it. I know it's cheap.

[moritzthecat]

fully agree ... and understand efforts involved and potential impact in case of wrong content.

Over the years, we have made several attempts to gather information from the EMS-ESP user community and store it centrally, ...

maybe I have overlooked. could you pls. help me finding these valuable resources.

still, what is known today may help new users getting started more quickly and highlight issues, where behavior is still unclear thus where to be careful changing such parameters.

content could be added incrementally by a community voting process like implemented in stack overflow, where needed. this could offload some work from core team ... and keep content fully community driven and thus transparent. also would limit the issue of indirect liability. the voting result could be added as confidence level indicating where parameters and system architecture is still unclear.

IMHO such approch could move the project to a next level towards better system understanding. but going such direction has to be carefully investigated.

[nicoleise]

I could help with this, if you can tell me how to. I recently setup an EMS gateway on my Compress 7800i (very common Bosch ground source heat pump), and I am a building management systems (BMS) engineer by trade, and somewhat good at describing things in a correct and not too ambiguous way.

I will (if possible, I have an issue with MQTT) be connecting my heat pump to my own BMS and to Home Assistant. In addition I have a bunch of extra sensors and other components installed on the connections for the heat pump.

For example, I suppose the example by @proddy refers to the domestic how water (DHW) profiles. They tie into options hidden in the installer menu that specify the start and end temperature of the DHW tank.

The tank is cooled by usage of DHW, which lets new, cold water enter the tank, as well as by loss of heat to the surroundings. Eventually, the water will be so cold, that a warm up cycle must begin. This is referred to as the start temperature.

When the water is heated, it will obviously get hotter and hotter, so eventually one must stop adding energy to the DHW. This point is called the end (or stop) temperature.

When showering, you'd usually use water around 35-38 Deg C, so we calculate how much water you can use for a shower at a mixed temperature of 40 deg C. Since the water is mixed, if your DHW is very hot, you'll be using a smaller quantity of it to achieve 40 Deg C. So it "goes further". But it also increases the heat loss to the surroundings and costs more because more energy is needed. Especially for heat pumps where we like the flow temperature to be as low as possible.

The profiles are something like in start and end temperatures and resulting volumes of water when mixed to T40.
Eco+ 42-54 deg C, approx. 200 L at T40
Eco 48-58, approx. 250 L at T40
Comfort 50-62, approx. 300 L at T40.

In addition there's an "extra hot water" input which will likely increase temperatures even further.

These profiles are an obvious way to implement smart grid and alternative energy, for example photo voltaics. Here we have cheap night tariffs and medium during the day and very expensive 17-22. The heat pump out of the box supports setting schedules for these, so until I can integrate into the BMS, I simply use Eco all day, except Comfort at 5:30 to ensure the DHW is heated up just before the tariffs increase and switch back to Eco at 17 to minimize the odds that it will produce DHW in the expensive tariffs.

However, there are European and national standards about water temperatures, and so far as I can tell, only the comfort profile strictly adheres to these.

Anyways, I'll obviously be going through the process of analysing nearly every "handle" this heat pump has to offer in order to optimize it's controls. So if I can share that somehow to help, I don't mind at all. But if so, please point me in some direction. :)