Questions around Open Energy Monitor and pulling it into Home Assistant

Forgive me if these seem silly questions but I am really new to all this and I am no heating engineer. Got to start somewhere.

Over Each Time Period…

What is my…

INPUT heating used in kWh (Radiators)
OUTPUT heating used in kWh (Radiators)
What is the COP for the Radiators
INPUT heating used in kWh (Hot Water Tank)
OUTPUT heating used in kWh (Hot Water Tank)
What is the COP for the Hot Water Tank

What is my combined COP

Are there two ways to heat the HW tank / Radiators e.g. Heat Pump and Immersion

Octopus Energy fitted a Daikin 4kW heat pump, a water cylinder in a upstairs cupboard, and smaller buffer tank just below in garage.

If on immersion am I getting Negative COP or 1:1 input/Output - Is that negatively impacting the SCOP, does 2.86 seem very low, from what I heard should be getting nearer to 4 and higher at this time of the year so what’s it going to be like in winter when the temperature drops more?

What is the significance of Flow Temperature, should it be low or high? What should it be?

Is Electric what I am acutally taking from the Grid for Heating and Hot Water at this moment in time? And likewise assuming Heat Output is what I am getting back for what I am putting in here. e.g. putting in 14 w but getting nothing back ???

The Total Input and Output - Does that not get broken down by Hot Water and Radiators?

I want to pull all the above into Home Assistant so I can see it against my actual electric usage for all things other than Heat Pump I got the following 8 entities only though.

EmonCMS electric_Energy
EmonCMS electric_Power
EmonCMS heatmeter_DeltaT
EmonCMS heatmeter_FlowRate
EmonCMS heatmeter_FlowT
EmonCMS heatmeter_Power
EmonCMS heatmeter_Power_kwh
EmonCMS heatmeter_ReturnT

How would I get these values into home assistant so they report over various time periods?

is it normal for hot water to go from 60 degrees at midnight to 48 degrees by 3.30pm, so within 15 hours a drop of 12 degrees on a Daikin Evocyl 250L tank?

It seems excessive, that would be a 250 W loss rate which is around 4-5x what I would expect. Do you have a circulation pump for your hot water?

1 Like

I have no idea - question for Octopus Energy who fitted it

The hot water circulation pump would be a feature of your hot water pipe system, not the heat pump itself. Does the water get hot immediately when you open a tap or does it take a while?

it takes a while for the hot water to come through, it’s cold to start with

So probably not a DHW curculation pump in your system. Other things that come to mind:

  • Something’s drawing hot water all the time/leak? Can you check whether your water usage is unusual?
  • Sensor issue: The DWH sensor is at the top and doesn’t really represent tank temperature, especially right after top up. It equilibrates after heating the tank and decays more slowly later on. Can you somehow check a time curve of your DHW temperature?
  • You did have a DHW circulation pump in your system at one point but now it’s not there any more/broken. There might be gravity-driven circulation that slowly circulates warm water through the system. You can find out whether there’s such a pump in your system by checking the number of pipes entering your tank. There should be a flow and a return pipe coming from the heat pump. Then a cold water pipe going in and a hot water pipe coming out. If there’s an additional pipe thats getting warm even when you’re not drawing hot water (or the hot water pipe is warm even when you haven’t drawn any water for some time), then that might be the problem. That’s probably a very long shot but it happened to me so I’m bringing it up :wink:.

No idea but just tagged in Octopus Lead installer as that concerns me a little if there are leaks etc…