Ever have your central AC unit turn off all of sudden? If your a home owner, this is a common source of annoyance. It's the most common reason why service is called for. The air conditioner condensate drain line is blocked. The solution is to clean the AC condensate drain line every month with a 1/4 cup of vinegar then flush with water once a month. You have to remember to do this tho and it's easily forgotten. Should be done more frequently to prevent any mold or bacteria build up. This post is a how-to-guide to configure an off-the-shelf smart wifi dual water pump to flush out this line on a regular basis.


  • Flash the device with Tasmota firmware
  • Set up a water reservoir
  • Route water line to the AC condensate drain line opening. Usually near the start of the heating/fan unit.
  • Add rules to manage water pump timing and notifications.

Water Pump Preparation

I ordered this wifi dual water pump from Amazon then flashed it using this guide. The only tricky part was soldering wires to those tiny connections shown in the guide's image. I followed the traces for two of them then soldered unto those instead. More room to work with.

Flashed it with Tasmotizer. Send the wifi configuration then grab the IP address. Make sure to set the template defined in the guide at this point in Configuration > Configure Other.


In order to monitor the pump activations, a counter was added. This is useful to keep track of the amount water/vinegar mixture is left in the reservoir. This needs to be done after the template was set by going to:

Configuration > Configure Template > GPIO16 to Counter with counter drop down selected as 1. The value is stored even after a reboot!

Set up a Water Reservoir

Take a vinegar plastic bottle and poked a hole in it about the size of the fitting. After that, hot glue in one of the fittings the came from the water pump supplies. Be sure to poke a hole in the top so air can enter the bottle.

Plastic bottle fitting

Tasmota Rules

Add this rule when the pump1 has started. It will schedule to turn off in 30 seconds which should disperse about 1 cup of vinegar/water mixture. Increments one to Counter 1.

Rule1 on power1#state=1 do backlog RuleTimer2 30; counter1 +1 endon on Rules#Timer=2 do power1 off endon

Rule1 on

Turn on pump one every day at 4am within a 15 minute window.

Timer1 {"Enable":1,"Time":"4:00","Window":15,"Days":"SMTWTFS","Repeat":1,"Output":1,"Action":1}

Timers on

Set the timezone of your location.

Timezone -8

Lastly, if the device restarts then ensure the water pump relays are off by default. This is not the default with Tasmota firmware.

PowerOnState 0

All of it together:

Final results for the web ui

Tasmota WebUI

MQTT Sensor topic

tele/tasmota_XXXXX/SENSOR = {"Time":"2021-12-31T09:39:59","COUNTER":{"C1":3}}

Future Improvements

  • Based on the counter, send an alert to refill the reservoir tank.