Predictive heating/cooling template construction?

Configuration
1

I’m trying to write a template that compares the time to achieve a setpoint based on the current time and current temperature and a known achievable deltaT

This is what i have but i think it has trouble with the format of the time. I have tested the theory in a spreadsheet and need help writing the template correctly

{{states(‘sensor.ice_bath_esp_ice_bath_temperature’)|float - states(‘input_number.ice_bath_setpoint’)|float > states(‘sensor.time’)|float - states(‘input_datetime.ice_bath_target_time’)* states(‘input_number.ice_bath_deltat’) }}

1 Like
2

This part is probably not valid. If you are using the basic sensor.time, it’s state will be a time string like “10:00” which will produce an error when the float() filter is applied.

Is the input datetime time-only?

Keep in mind that all states are strings, so you need to apply an int() or float() filter to the state of the input number as well; or you will get a type error.

3

changed to this:
{{states(‘sensor.ice_bath_esp_ice_bath_temperature’)|float - states(‘input_number.ice_bath_setpoint’)|float > states(‘sensor.time’) - states(‘input_datetime.ice_bath_target_time’)* states(‘input_number.ice_bath_deltat’)}}

and receive this error now:

TypeError: can’t multiply sequence by non-int of type ‘str’

so i guess i need to convert the times and/or input_number to float? (integer wouldn’t work for the deltaT)

4

We can’t help if you don’t answer questions…

Also, what unit of time should be returned from the subtraction of the two time elements?

5

oh sorry!
Er yes, just time.

Ultimately what i’m trying to get out is a boolean on whether the time to achieve the target temperature is less than the time available, so i can delay running a chiller until it needs to turn on.

I guess it’s reading as (difference in temperature) > (achievable temperature in available time)

6

You’re going to need to use something like:

{% set temp_diff = states('sensor.ice_bath_esp_ice_bath_temperature')|float(0) - states('input_number.ice_bath_setpoint')|float(0) %}
{% set cooling_time = (today_at(states('input_datetime.ice_bath_target_time')) - now()).total_seconds() %}
{{ temp_diff > cooling_time * states('input_number.ice_bath_deltat') | float(0) }}

But you will need to divide cooling_time by the appropriate value to convert the seconds into whatever unit is used in your delta_t.

Also, be aware that this basic version of time math will not work across midnight because of the use of the today_at() function. If you need it to work across midnight you’ll need to make some changes to the target time.

7

Many thanks!!
It returns a boolean result.

The deltaT is in degrees with a resolution of 0.1 (it’s currently set at 1.8 degrees/hour)
I don’t need it to run over midnight for the next 6 months at least, but i suspect as outdoor temperatures start to rise next spring and definitely summer, it will.

8

What changes do i need to make to cross the midnight threshold? I realise if i want this to be active all the time i will need it to work over midnight. Otherwise i’ve got to only enable my automation after 00:00

9 
{% set temp_diff = states('sensor.ice_bath_esp_ice_bath_temperature')|float(0) 
- states('input_number.ice_bath_setpoint')|float(0) %}
{% set today_dt = today_at(states('input_datetime.ice_bath_target_time')) %}
{% set target_dt = today_dt if today_dt > now() else today_dt + timedelta(days=1) %}
{% set cooling_time = (target_dt - now()).total_seconds() / 3600 %}
{{ temp_diff > cooling_time * states('input_number.ice_bath_deltat') | float(0) }}

EDIT: Fixed variable ID typo

10

Thank you,

Unfortunately that made it go unavailable. I’m reading and rereading it and nothing jumps out at me, but i’m a novice.

11

There was a typo in one of the variables, I have corrected it above.

12

yep, fine now thank you!