I recently bought one of these crawlspace dehumidifiers for a project, Sentinel HD55. I am looking to automate it for wifi remote control. I contacted the company to see if they would give me some more info about it and the remote control wire port as it is just a cat5 connection.
They responded with some good info. From what they sent it appears that you can do this with a relay board and a ESP32/8266/etc. Possibly even just an ESP32 with enough pins. I am trying to get a little more info from them to make it as simple as plugging in a cat5 pigtail wired to some relays.
Is anyone else interested in this type of control? i.e. wifi remote control of your home dehumidifier? This is a really great unit. It ticks a lot of the boxes. I am not using it specifically for home humidity control. But it is perfect for what I am building sans one thing. You cant just power it off with an sonoff S31. It has a cool down timer set to turn of the compressor but still run the cooling fan for several seconds. If you simply cut power the compressor can be damaged. Hence why I contacted them.
Maybe if there is enough interest they will be more forthcoming with information about the internals.
I’m about to order one right now also. That’s really interesting to hear they were responsive with some actual technical info. Sounds like you basically duplicate the remote control humidistat…
Yes. They were not forthcoming with any more info however. They stated that they were in the process of doing a wireless controller as well. Not really helpful with their controller as far as homeassistant goes. Here is what they did send. I hope it is helpful to someone else as well.
I dont think this matches my controller board exactly but just the connect/disconnect info and split pins should be enough.
Looks like the board in the remote control, not the main one on the unit. I’m surprised they sent you that along with written instructions on how to tap into it, ha…
Duplicating the buttons would be easy enough to do, but would be nice to figure out how to get the humidity values somehow. Either way, just being about to remotely turn on/off properly would be great. I will play with mine this weekend and see if there’s a way to at least get on/off capability from the pins on the machine without needing the remote like they are showing you.
I picked up an Aeotec Z-wave multisensor to measure humidity separately, so maybe the combination of that sensor and figuring out how to trigger on/off from the connector would be sufficient.
Good point. That probably is the remote panel. Yeah I was surprised they sent anything but hey if you never ask…
It would be nice to get the humidity temps I agree. I am also using external temp/humid sensors so it is not a deal breaker. I just wanted to control it remote without damaging it.
It looks like this documentation on the website describes the screw terminal signals.
The A3 and A4 pins looks like they turn on the dehumidifier, the idea being you can have it run whenever you’re running your AC. The one issue being that it expects a 24VDC signal applied to A3-4. You also need to access the motherboard and turn switch SW1 to the “On” position
Pin
Name
Description
A1
NO:
Normally Open
A2
COM:
Common port
A3
ON-D:
External input (24Vac/DC)
A4
COM:
External input (24Vac/DC)
A5
FLOAT:
External low voltage float switch or water sensor (use normally open switch)
A6
FLOAT:
External low voltage float switch or water sensor (use normally open switch)
A7
VCC:
Humidity transducer “+”
A8
DATA:
Humidity transducer DATA
A9
GND:
Humidity transducer “-”
Here’s a quick summary of everything else in case that pdf ever goes away
A1 and A2: relay output that closes when dehumidifier is running. Intended to be used to run the furnace/AC fan at the same time. Could be used as an indicator into HA.
A5 and A6: connect a NO switch. Used for a condensate pump to indicate that the pump is broken, water level is too high, and inhibits the dehumidifier from turning on and making the water problem worse.
A7, A8, and A9: The humidity transducer looks to be a input to turn the humidifier into ventilation/air circulation mode when the outside humidity is low and you are bringing in outside air. I’m not sure what type of signal it’s expecting or what the conversion to humidity would be.
Just cracked my Sentinel HD55 open, the RJ45 connector has 4 wires internally. These 4 wires terminate at the main PCB and are labelled CAN-L; CAN-H; 0V; and VCC. I’ll go out on a limb here and say it’s CANBus. Lot’s to think about now.
That looks like an excellent start, thanks for finding that!
I’ll eventually get an ESP32 setup with the CAN level shifter I have and see how that goes.
I also just got an HD55 and am new to home assistant but love it already.
I got the external remote, and regret it. It costs $100 and it’s overpriced, especially for us. I bought the remote a while ago before I got into home assistant.
Anyways, I was thrilled to see others were looking into hacking the remote signals, but now i’m thinking why bother?
The built in humidity sensor is probably not great claiming +/- 5%, and home assisant has a generic dehumidifer module that basically needs a sensor and a relay on esp32 to function. I havent tried it, but it looks perfect.
I love the mechanical and electrical I/O aspects of the product itself, but I would just assume use the built in sensor only as a fallback, and control/monitor the unit using home assistant via the screw terminals.
The idea of the unit being able to use an external fan to draw outside dry air inside is interesting, but what about the temperature of the outside air??? That’s also important, so I would not want the humidifier to have that ability.
Does the can bus route have any advantage, besides not needing to add a relay and humidity sensor??
Edit, so it appears controlling the unit externally with the 24v input requires you to disable the built in logic. Still seems worth it for me, but worth noting.
I have built a plenum and hooked up a 4" and 6" inlet. The 4" has a powered damper so I can control the outside air during the summer (cooling) season and the 6" draws air from the main floor.
During the heating season the HRV is running to bring fresh air in. Both systems are triggered based on indoor humidity and indoor CO2.
Regarding the CANBus, I think it is cleaner than a box of relays wired to the front of the machine. Yes there is an investment of time to get it figured out and eventually running, but after that it is easy to share.
I have 7 BLE temperature and humidty sensors distributed around the house and use “Thermal Comfort” to get dew-point and absolute humidity for inside and outside so I know what to turn on.
Olimex makes an esp32 with 2 small relays and ethernet (and canbus) it could easily be hidden inside the machine using the internal pins as cleanly as you could using the can+esp32. However, providing 24v just to trigger the machine is less than ideal, even hidden.
I would probably go the can route if the integration existed in home assistant but I need something soon.
If the ESP32 CAN stuff in ESPHome isn’t sufficient I will have a look at that. ESPHome is limited to a single packet, but that doesn’t look like an issue give the work done by “tinymicros”.
I’ll check out the Olimex part as well because that would work well for several things on my list.
I have the olimex board already, I didnt realize esphome had a can integration. If I have time tonight i’ll absolutely plug it in and mess around. That’s great intel.
What are our thoughts (gueses) on how much the 5v rail at the RJ45 can supply from the HD55? I dont have any way to measure the current the remote control is using, but obviously powering the esp would be ideal.
I have since realized that for my wood working and laser cutting purposes in my shop, relative humidity is not ideal for humidity control because the temperature can fluctuate from 60-95F indoors in summer. Targeting a specific relative humidty would only work for me if I had a roughly consistent indoor temp.
I need absolute humidty, so the internal controller the HD55 comes with is out for me, thus the canbus to esp32 option is dead too. I’ll be going the external control route…
Since I will not be using the oem canbus remote I purchased, I am willing to donate it to anyone who thinks it would assist them creating some typeof esphome or similar integration for home assistant.
Let me know if you’re that person, or you know who that person is.
Before giving up completely, have a look at Thermal Comfort, it will take temperature and RH and calculate the absolute humidity
This will output absolute humidity like this
I hate humidity year round. If you are packing it in I will eventually get to the CAN interface and would be interested in the remote. ESP32 and CAN interface are sitting in my desk. I live in a tight newer home and also monitor CO2 to open and close a motorized fresh air damper for the dehumidifier.
For my workshop I have the IKEA PM2.5 sensor with the D1mini in it to log air quality while I am cutting and sanding
I have the same humidifier and solved the automation issue by setting the humidity level on the unit to it’s lowest setting (36%), and just turn it on and off with a Shelly Plus wall plug. It uses about 440 watts when running. Nice thing about these Sentinel dehumidifiers is that they always turn on with the same setting even after the power is cut.
I use an Ambient weather station to get the outdoor temperature and indoor humidity. Since ideal indoor humidity is based on the outdoor temp, I only turn the switch on when the indoor humidity is above the target value based on the outdoor temp. I use Node Red to control the on/off cycles, making sure to only allow it to cycle once per hour. This beats having to manually adjust the units humidity setting manually as the outside temp changes.
My understanding is that there’s no issue with cutting the power off this way - the reason for the cool-down period is to evaporate the moisture from the coils so it doesn’t freeze up. By making sure it’s always off for at least one hour I’m sure it’s never going to freeze. When the humidity and temps are high it typically runs 50% of the time. It’s been going strong this way for over a year now with no issues. Coupled with a condensate pump there’s zero maintenance!
