Minimizing cost of using the heat pump and pellet heater with changing electricity spot prices, solar panel production and outdoor temperatures

[Vahur_Tamuri]

Hello

I’ve been a Homey user for a week now and I’m trying to learn how to use the device. Unfortunately, I have run into a conflict that I cannot resolve. I tried to create advanced flow for the heating system with different arguments, and this morning I discovered that the relay does not switch based on the given criteria based on the outside temperature. Maybe there is a logic error with flow?d to show, and explain the working of specific Flows in homey.

[Paul_van_Ulft]

@Roy: the red circle is not wrong.
However thereare so many arguments in this flow. and they can stop the 4elay. Also, whyturn the relay offwai 30 mins andturn offagain.

[Vahur_Tamuri]

I had no idea that the layouts of different windows also play a role in advanced flows. I can move the temperature sensor window more to the left, but I don’t think it makes a difference. But I will definitely try.

[Vahur_Tamuri]

Thanks for thinking along. The 30-minute delay is so that the pellet heating has time to heat up the battery tank before the Nibe air-water heating system switches off. Otherwise, there will be a lack of thermal energy and no hot water.

[DirkG]

It doesn’t matter at which local position a flow card is.

This flow card is only triggered when the temperature drops from above -6 °C to below -6 °C.
What was the temperature this morning? Can you post the temperature diagram (Insights) of this sensor?

[Vahur_Tamuri]

[DirkG]

There is a really small section, where the temperature drops from over -6 °C to under -6 °C:

Overall, the temperature is only rising.

Theoretically, the pellet stove could have been switched on. As the data points are more or less interpolated in Insights, the diagram may not be correct. But I don’t know that exactly. In addition, the pellet stove could also have been switched off again by PBTH’s “Spot Price” card.
So there are several influencing factors coming together which only can be checked by yourself at this moment.
My recommendation is to add notification cards with corresponding information (price, temperature, etc.) when the pellet stove is switched on/off to check when and why it was switched on or off.

[Rrrr]

@Vahur_Tamuri As indicated by @Paul_van_Ulft and @DirkG you have multiple triggers that can turn on or off the pellet heater and heat pump.

If still relevant to you, there is a lot to go through like streamlining the conditions and ensuring that the static 30 min wait won’t interfere with new triggers, but let’s take it step by step.

Model 1.
I have tried to show your flow in an organized manner, but I am not sure I follow the logic. It would be useful if you can explain. (just for the example, I am not using your exact cards)

Triggers turning on:

@Vahur_Tamuri

The 30-minute delay is so that the pellet heating has time to heat up the battery tank before the Nibe air-water heating system switches off.

• Your flow shows that the heat pump is turned ON about 30 min after the pellet heater. Should that not be OFF?
• If less than -6C you turn on the pellet heater, but you do not switch (off) the heat pump, correct?

Triggers turning off:

• Spot price(< 12): you are turning OFF only the heat pump. Correct?
• Solar power (>2500W): turns off both the heat pump and the pellet heater
• If > -5C: it turns off only the pellet heater, but not the heat pump. Correct?

I added a simple way to log the changes, so you can track in real-time.

[Vahur_Tamuri]

Hello

First of all, thank you very much for showing interest in helping. I will try to explain in my broken English what and how I would like it to work.

• I would set the limit price of electricity to 12, above which the pellet heating will turn on and the Nibe blocking will turn on after a 30-minute delay (the automation of the Nibe system continues to work, but the air heat pump is blocked. The 30-minute delay is necessary so that the pellet must first be able to heat up the water in the battery tank and the delay helps prevent power shortages in cold weather.
  Also, if the temperature drops below -6C, the pellet should start working and the Nibe pump is blocked after a 30-minute reference (Nibe Turn on).
• If the price of electricity becomes cheaper than 12 cents and the temperature is warmer than -6C, the Nibe pump blocker turns off and the pellet heating is also turned off. Here, a 1-second delay is necessary so that the dual-channel relay does not fail. At some point I discovered that when they received the command at the same time, both of them did not switch every time. With a delay of 1 second, the switching of both channels worked correctly.

Kontakt Rrrr via Homey Community Forum (<notifications@athom.discoursemail.com>) kirjutas kuupäeval T, 2. jaanuar 2024 kell 02:16:

[Rrrr]

In your new flow you have multiple triggers that are connected with an AND. This means that the next step in the flow is unlikely to ever happen. I prefer working with combining conditions instead of using the AND card. AND cards make flows hard to understand and are error prone.

Model 2 is what you have defined minus the errors. It is very important you formulate your expectations clearly with AND and OR, like if it’s math.

If this THEN that
If this OR this THEN that
If (this AND this) OR (this AND that) THEN that

The below still has some weaknesses:

1. Still to define is how solar power will affect your state
2. Does not deal with fluctuations

• This may lead to repeated on and off of the pellet heater. Because of the static 30m delay, the Nibe block may still activate even if a new condition wanted to turn it off. Therefore we use timers that can be cancelled. I will show later.
• Even using a timer, I am sure you do not want you pellet stove to switch on and off every 5 minutes (when spot prices or temperatures fluctuate), so you probably need to define a minimum working time before you allow a state change. After that minimum working time you need to test the same conditions again to determine a new state.

[Rrrr]

Model 3 with:

• An assumption on Solar Power and a minimum pellet heating of 120 min
• A boolean helper that keeps track of the wished state: at any point when triggered, the conditions are tested in a prescribed order: first solar power, then temperature, then spot price.
• A countdown timer that acts as a block and trigger to start/stop pellet heating until it is finished. Important is that the minimum duration is >30min or you will need to add another timer.

You may consider additional triggers and related conditions to ensure the heating is switched off when you leave the house or when it is night.

(corrected version)

[Vahur_Tamuri]

Rrrr, you have really and quickly drawn me into the world of Homey and opened my eyes to different possibilities. If in Estonia we offer a lot of central devices of the “Smart House” principle of different manufacturers, then today I am convinced that Homey is the most universal of them, which is constantly updated over time WITH ALL OF YOUR HELP.
I believe that even in this environment, you will definitely reveal to other users what and how your solution-approach offers…