Equipment required?

[xdaviddx]

Hello,

I am considering getting a Goodman/Amana air conditioner condenser that supports ComfortBridge communication. Is there any other "communicating" equipment I would need in order to try to request information from the condenser or to send messages to it in order to control it?

To say this another way, are the messages documented or does the system have some sort of discovery mechanism for all messages a device supports? Or will I need a thermostat/control board that knows how to communicate with the condenser in order to log and reverse engineer the communications?

[kpishere]

Hi. Short answer is yes, you'll need a thermostat. I'm attempting to build up source from the now outdated open spec. of a few years ago. The open effort fell apart a few years ago when those on consortium started suing each other.

This is still an experimental project. Takes long time to do as tools must be made along the way and test frameworks etc. Still though, the diag tool can be useful against a working system to observe communications.

Note that in some other conversations here, you'll see some keywords that will help you find these specs. The open site is offline now.

[xdaviddx]

Thanks for the explanation. Just so I understand...

I would need a thermostat so that I can figure out which messages need to be sent to the condenser. But after I have that information, I don't need the thermostat, as your libraries would take the place of the thermostat? (I am speaking future state, when your libraries are more full featured)

Regarding the open effort, does that mean each company is using the same basic protocol, but after things fell apart, they have drifted apart and devices can no longer interoperate across vendors?

[kpishere]

That is pretty much the case, I suspect. Vendors are blocking portability either by manufacturer IDs or they have extended funtionality that isn't compatible with other systems. I'm expecting it is more the former.

As far as the status of this project, I've done some initial low level development and testing. But now, I'm gonna have to re-tool and adjust the library. This physical way I've been doing it is too slow. I need to virtualize it more so I can make simulated RS485 networks and set up automated regresion test suites. A side benifit of this is that the code base will be more portable.

Here is a link to a discussion about the subject.

https://community.openhab.org/t/hvac-climatetalk-protocol/8367

If you focus on the specifications at the application level, the communications are streightforward.

Thermostats are in the 300-500$ range -- way cheaper than kind of effort this project has taken! :)

[xdaviddx]

Would manufacturer IDs be the better outcome, since then it is just a matter of knowing the ID and using it in the messages?

It does sound like a lot of work. Thanks for the link. I'll check it out. UPDATE: I believe that is the same thread that I read and where I found your github page. :-)

I am doing this as part of a custom HVAC control system for my house, so I can't incorporate proprietary thermostats very well. And even if I could, I don't want to be locked into or support anything proprietary. But I could certainly buy one, possibly used, and resell it after getting the messages captured. :-)

If I go with 2 stage condensers, then I don't really need the ClimateTalk communication. I think that will only get me extra status information from the condensers/compressors. Some of that may be temperatures, and those might be valuable to have, but I can also put my own sensors on things and read those without needing to go through an advanced protocol.

If I go with variable speed condensers, then ClimateTalk would allow me to take full advantage of the efficiencies of the system, by ramping down and up, rather than just using them at high and low speed. If I'm able to source the variable speed condensers, I'll use them in 2 stage mode until I can figure out a way to control them across the full speed range. It might be possible to control the condenser inverter board directly, bypassing whatever electronics the vendor has put in place to do so. That would probably be through analog signals (0-10 volts DC or Pulse Width Modulation).

Thanks again.

[kpishere]

Yep, pretty much. FYI, I'd done somthing industry types say you can't do. I bought an inverter controlled ductless heatpump, a Goodman A coil of appropriate size, and had the compressor part of the ductless unit (which has electronic TXV controls in it) installed in the usual way but with the inside being hooked up to the goodman A coil rather than the interior part of the ductless unit. The electronics were stripped out of the interior part of the ductless unit and other then fooling the interior electronics that the internal fan was connected, it works fine. I get nice perportional control on cooling/heating. Note that the two interior thermocouples were relocated to the right spots on the A coil -- that being entry air flow point and the mid-point on the coil. Other important point is that the orfice is removed from the A coil as the TXV vavles in the heatpump compressor are already doing that funciton.

[xdaviddx]

Wow, that's an interesting setup. Let me see if I understand correctly.

• You have an outdoor ductless mini-split heat pump (that happens to be variable speed)
• You have a goodman evaporator coil inside a regular air handler inside
• You have the outdoor heat pump connected to the evaporator coil instead of being connected to the normal air handler of the ductless mini-split installed in a wall.

Is that correct?

Questions:

• What brand heat pump?
• Why did you go this route instead of using a regular split system heat pump condenser?
• How did you know how to set the superheat when charging the refrigerant into the system? Was it assumed it should be the same as for the normal in-wall air handler/coil?
• How do you control it in order to get the variable speed on the heat pump?

[kpishere]

The branding is Sendville (also seen same unit as Mr.Cool). This option was under 2.7k$CAD where for same feature set for central system it would have been 8k$CAD.

System is charged by weight, it is fully electronic so measuring SH is less meaningfull. Goodmen coil has slightly more volume than original evaporator so i did increase charge amount by about 5-10% from listed system amount. Sorry, forget a bit right now, it was 2yrs ago. I do recall checking overall system pressure whilst running on ... low side? (you only get port access on one of the sides on these systems).

Note the system does have one of those Toshiba compressors that are well suited to variable control (none of this two stage copland compressor stuff).

Control wise, i had to fool the interior circuit into thinking that the internal fan was present. It has a 3phase fan motor (BDLC?) that takes a PWM signal and has a feed back signal to measure speed. I replaced the fan with a good ol. 555 timer chip to do this. That is, provide the needed feedback to fool the system that the fan is present and at speed.

So with thermal sensors on the goodman coil, this is info the external compressor board uses to control compressor and external fan. It just works.

The annoying thing right now is that i must set house thermostat to cool - which only turns on air handler fan at a set speed, then go to basement and turn on heatpump with its remote to set to cool.

If i had this integrated with this network stuff, there could be varying internal air handler speeds and no running to basement to set modes.

All in all, it still works well like this, temp is steady and humidity is low, under 60% and we've experienced 42degC with 90% humidity around here recently.

That is 1.5 ton unit with a well insulated 2800sq.ft. 2story house.

Also, another motivation for electronic communication to work is so that i could add a control in ducts to direct more air upstairs in summer rather than messing with floor vents twice a year.

And yes, the unit is quiet and runs in steady state most of the time!

[xdaviddx]

It is funny how they can have all this advanced technology and still cost less than a regular split system. And the traditional systems are trying to hold onto this profit margin through proprietary lock in instead of modularity and customer choice.

Oh, so you took the control board out of the mini-split air handler, and it is still being used to control the inverter outside?

Regarding needing to use the remote in the basement, maybe you could wire in a board with an IR transmitter that would send the codes to the mini-split board when the thermostat calls for AC or heat? Or do you only need to do that during the change of seasons?

Does your air handler have a variable speed motor? I have a PSC motor now, but will be changing it out for an ECM to be able to control the air movement and greater efficiencies.

I am surprised you are able to keep humidity down with the fan running faster than the load requires. I guess if it runs for a longer period of time, it will still take out the moisture, just at a slower rate.

I have been thinking about duct dampers/electronic registers too. If you have separate ducts for upstairs and downstairs, could you add a zone control board before the heat pump board and a couple dampers in the ducts? I have 3 zones and it is set up that way, with the zone board taking all the thermostat inputs and then passing those on to the air handler board.

I guess one big difference in your system vs most normal split systems is that it is monitoring the temperatures on the coil. That allows it to make smart decisions about what speeds to run at to get close to satisfying the thermostat but not overshoot it, even without having the thermostat temperature readings.

[xdaviddx]

Where in Canada is it that hot right now?

[kpishere]

The southern parts do get that hot sometimes, most people live along the border with USA. It was like that were I was a week or two ago. That is likely to be the peak for the year.

Those are good suggestions. I can make specifc circuits to do what you say, is true. But this is now more about what should be.

Yeah, I only need simple zone control. Two zones would work for me in this house. That is another project, creating own thermostat where you just add wireless thermostats to control. There are some pretty cheap modules that have very long battery life out there that transmit temp and humidity.

Yes, current air-handler/furnace is 2-stage with ECM motor but my thermostat is non-communicating so I don't get that benifit byond gentle starts and long run-times for furnace in moderate to cold conditions.

[xdaviddx]

Those are hot temperatures. I am in Minnesota. Luckily, it doesn't get quite that hot here. I think we did have a 97 F day earlier in the spring, and have had some other mid-90s F too.

I am looking into temperature sensors as well. Sonoff TH 10/16 aren't battery powered, but they support different plug in sensors. You can run a custom firmware (tasmota) in them for better support for integration. I will be using a different model for keeping track of whether some outlets that are running freezers are still powered (S31) and possibly to automate restarting my parents' printer when it gets confused.

Or a sonoff basic device can have a temperature and humidity sensor added to it, like this person did: https://notenoughtech.com/home-automation/nest-your-old-thermostat-under-5/amp/
I need a battery powered type for my freezers to make sure the freezers haven't malfunctioned. For that, I am going with some iris 3320-L sensors. You can get them inexpensively, used on ebay. People report good battery life, despite the cold temperatures. There are also "wireless tag" varieties. I haven't decided what to use for room sensors to compliment the thermostats. If you end up finding something that works well, I'd be interested in hearing what you used.

I am going with regular thermostats vs home grown. One reason is that I am going to try to make my system work even if my custom pieces fail and in case I ever sell the house. The thermostats I am going to use are Venstar Color Touch T7900. There are different models, but that one has temperature and humidity. These are wifi accessible thermostats with a local REST api to control them and read information. They aren't the cheapest, but are apparently well supported, and family members will be able to use them easily too.

Oh, I thought you meant the mini-split board could somehow change speeds on the blower motor. 2 stage is still much better than single speed.

I just ordered an ECM motor today (genteq evergreen em) to replace the PSC motor I currently have in my air handler. I'll use the built in speed taps to start with, which will still save me some electricity on slower speeds. I recently installed an energy monitoring system (Emporia Vue), and found out that my blower is using a lot of power. I have the thermostats set to have the fan always running, even when the AC isn't being asked for. That's to mix the air upstairs with cooler air from the main level/basement. Hopefully the ECM motor will be cheaper to run.

Eventually, I'll get a special wiring harness for that ECM motor that will allow me to change the speed on the fly, anywhere from 600 rpm to 1200 rpm, using 0-10 volts DC. That should allow me to optimize for dehumidification with my current single speed condenser, and later to change speeds along with the 2 stage or variable speed condensers I plan to get.

I understand what you mean about the way it should be (using ClimateTalk). :-)

[kpishere]

Here is the exact model I'd bought. https://www.walmart.com/ip/433MHz-Wireless-Temperature-humidity-Sensor-Outdoor-Weather-Station-Digital-Transmitter-Remote-Sensor-Thermometer-is-not-included/994871714

There are many out there. basically, they are 433Mhz wireless sending units to weather stations. This is better option than wire your own as they are optimised for battery life and pre packaged. Each has variation on protocol and you make your own receiver with something like https://www.amazon.ca/Aukru-Wireless-Transmitter-Receiver-Arduino/dp/B019SX6Y22/ref=mp_s_a_1_2_sspa?adgrpid=60522185229&dchild=1&gclid=EAIaIQobChMI36Oz_ITP6gIVIQiICR23lQX-EAAYASAAEgKgePD_BwE&hvadid=310002558714&hvdev=m&hvlocphy=9000687&hvnetw=g&hvqmt=e&hvrand=9930828340683346576&hvtargid=kwd-4909903487&hydadcr=518_1011850055&keywords=433mhz+receiver&qid=1594808595&sr=8-2-spons&tag=h0a61-20&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzOUdXUjU3WEwzOFU4JmVuY3J5cHRlZElkPUEwMDE5NzU3MkFZSjFPOUtNTVNZOCZlbmNyeXB0ZWRBZElkPUEwMjAzNTAxMTVQNUhGNk1RSzFUMyZ3aWRnZXROYW1lPXNwX3Bob25lX3NlYXJjaF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

or even SDR if you have one of those.

Also, I see zigbee sending unit in search on aliexpress too but not sure about battery life with those. Anything wifi will consume lots more power.

[xdaviddx]

That's an interesting idea. What type of range do you get with them? How long do the batteries last? Do they send out any type of information on battery state? I like that they have a display built in, so you can see the values, rather than just a sensor.

Yeah, for anything battery powered, I've only looked at zigbee. Those freezer sensors are zigbee.

[kpishere]

Range wise, there have been no issues around a house, from basement to 2nd floor. I think the range is quoted, you can control it somewhat on the receiver's antenna (full length is about 17cm for quarter length antenna but there are other options too). Batteries last 1-1.5 years. That model referenced does send battery state.

Yes, the display is a positive. In Practical way, tennents have been motivated to change the batteries themselves because they want it working to see temp and humid. A bonus for me.