Nest thermostat + esp8266 automation

Configuration
1

Hello all-

Its been a while since I’ve written a yaml automation, and I am pretty rusty. I have an ac unit that I’m controlling with Nest which I’ve integrated into HA as a Climate component and as a Nest component. Additionally I have a Node MCU with a DHT22 sensor and a PIR sensor inside one of the ducts which I’ve integrated as a sensor component. This is a way for me to verify that the blower is on.

I suspect that I have a faulty relay because the blower doesn’t always come on. I’ve ordered a new one, but until it arrives, I would like to turn the AC off if the blower doesn’t kick on within a given time frame. (its a time delay, SPDT type) When the blower kicks on, I get a motion detected reading, and the temp goes from 80 to 60ish inside 3 min, then down to 50 or so over the next 10. So, what I’m looking for is something like this:

wait 4 min
if temp < 60, keep AC on
else turn AC off

Can anyone point me in the right direction?

Best,

R

2

hello,:grinning:
I like your idea
however am still new to the HA game
but what I know (from work exp.)
you should use a DPS sensor / switch (differential pressure switch )
https://www.14core.com/wiring-sensirion-i2c-digital-differential-pressure-sensor/
or use a conventional DPS switch (https://www.aliexpress.com/item/Adjustable-differential-pressure-switch-air-pressure-switch-gas-flow-switch/1311322611.html?spm=2114.search0104.3.34.19eb20d10PQgkX&ws_ab_test=searchweb0_0,searchweb201602_1_10065_10068_5015511_10059_5015411_10696_100031_5016211_10084_10083_10103_451_5016111_452_10618_10307,searchweb201603_2,ppcSwitch_5&algo_expid=dfce4a12-5d94-46db-9ffc-53e86136adac-5&algo_pvid=dfce4a12-5d94-46db-9ffc-53e86136adac&priceBeautifyAB=0)
this will:

  • Monitoring Filters blocked Alarm Device
  • Monitoring air blower running status.
  • Monitoring air of ventilative pipelines
  • Controlling the largest gas flow of variable gas volume
  • Monitoring the gas of combustion furnace.

i would personally go for the conventional one since it i calibrated manually ( how much psi u want it ) and the triggering part is by closing a relay to completed the circuit or to send a signal

use this switch as an override switch so if the dps is not triggered the Nodemcu stays off (if running from batteries)

can u please explain more about the blower and AC setup ? you have a central chiller unit and a fan coil unit that feeds your house ?

3

Yes, split system, condenser outside. Your suggestion is appreciated, actually what I was looking for to begin with so thank you for that!! I know the DHT22 is not ideal, but this is a temporary situation (I already had it lying around) so I’m interested in just making it work, since I’ve already got it installed and am getting data out of it. Also, it will help to indicate problems with the compressor too.

4

as far as i know DHT22 is good for this type of applications and its cheap also , you need to know that the power consumption of the condenser is at its peak when its starting, so if you configure your AC at a high setting point temprature like for example 28 degree cel. and the ambient temp is at 30 degree cel , the condenser will eventually turns on and off a lot of times , thus consuming alot of power and shortening its life span

5

Yes, I know that, but it would not restart in the even of a blower failure. The automation would shut everything down by setting the thermostat to away mode, as mentioned. The AC system operates within a pretty constant temperature range. I want the automation to intervene only if the blower fails to turn on. It will determine if the temp is trending down as expected and thus that the fan is on as expected. Then it would text or email me that there is a problem, and set the Nest to away mode, disabling the compressor. This is only in a worst case scenario, not something that would regularly happen.

The consequence of keeping the compressor running without a blower moving air across the evaporator coils is catastrophic. The point of this automation is to avoid that.

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6

Those are some cool curves you’ve got here :grin:

try having a CT switch (current sensor relay) :grinning:
which it sense the current flow going in the fan, thus closing the circuit to feed the compressor and other parts,
but if the fan failed some how and stopped sucking amps the relay will Open and the system is shut down

7

try something like this

automation compressor_protection:
  alias: compressor_protection
  trigger:
    platform: state
    entity_id: climate.nest
    to: 'AC'
    for:
      minutes: 5
  condition:
    condition: state
    entity_id: binary_sensor.blower
    state: 'off'
  action:
    - service: script.notifyme
    - service: logbook.log
      data_template:
        name: Emergency
        message: ******************blower problem*
1 Like
8

Thanks! This will get me started, much appreciated.

9

This also seems like a good idea. I’m surprised these systems are not built with something like this from the factory!