Automate whole-home humidifier with Remotec ZFM-80

Community Playground General Discussions
#1

Hi,

I’m trying to control the 24v solenoid on my whole-home humidifier with a z-wave switch. I have a scene written that will check the outdoor temperature and indoor Ecobee sensors when the furnace calls for heat to determine if there is sufficient humidity in the house. If there is, it will not turn the switch on to run the humidifier.

The furnace control board has outputs on it for the humidifier - these outputs go to a 24v transformer. The 24v transformer then runs to the solenoid on the humidifier that turns the water on.

Normally, when the furnace calls for heat, the transformer receives power and the solenoid is triggered. When the furnace is finished heating, the transformer loses power, the solenoid closes and the water stops.

I’m trying to integrate a Remotec ZFM-80 into this scenario.

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I assume I need 120v running to “F” (AC input) - I’ve tapped into the house main for that. The switch powers up and turns on and off fine through z-wave. How do I get this switch to control the solenoid?

I still want the furnace to continue to control when the humidifier goes on or off. What I want to do is put the switch between the 24v transformer and the solenoid so that if the furnace does call for the humidifier, I can decide to keep it off if the house is too humid.

That said, I’m a bit confused on how to wire this up to outputs “D” and “E” above (if necessary). Any help would be much appreciated!

#2

Here are the two wiring diagram options they offer in the manual:

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#3

I believe the Ecobee is able to control either a humidifier or dehumidifier based upon humidity so you might consider moving the humidifier to the Ecobee from the Furnace control board. I have a whole house dehumidifier and it is controlled by a Nest thermostat entirely separately from the HVAC system so it runs when it needs to regardless of the HVAC state. In the case of a humidifier, I believe you will only want it to run if the humidity is below a certain level and the Heat is running but the Ecobee should be able to handle that too. You might even find that the Ecobee uses exterior conditions to intelligently humidify or not.

That said, for your relay solution, I would wire things in stages, confirming each along the way. Here are some ideas but “disclaimer” I am in no way responsible for your not following basic electrical safety precautions to avoid electrocuting yourself. If you are not comfortable with wiring up 120V circuits, hire an HVAC contractor to install the RemoteTec.

Powering the Remotec & Pairing with the Vera
The F terminals “power” the relay itself and the E terminals switch the load. So you want to turn off the breaker at your panel and connect the Line (hot from breaker box) to the L terminal and Neutral from your breaker box to the N terminals. I don’t see a ground terminal in the wiring diagrams above, but if there is a ground terminal, be sure to connect that now. Turn the breaker back on at the panel to power up the Remotec. At this point, you should be able to pair it with the Vera turn the RemoteTec on and off which will close and open the E terminals respectively. I believe you will hear a click each time you turn it on and off from the Vera. When you have this working, move to the next step.

Switching the Load (Humidifier) with Z-Wave
Most HVAC systems use 24V Transformers to power relays that open and close circuits for control loops. In your case, it sounds like the 24V Transformer’s role is limited to powering/controlling the Humidifier Solenoid valve. When the furnace controls open/close (most likely a relay itself), they open/close the 24V loop of the transformer across the Humidifier solenoid to open and close the value. I’m assuming the 24V transformer is always powered by 120V and the Furnace controls are only on the 24V side.

Now that you can control the E-terminals akin to a normal open/close (i.e. off/on) switch, you simply wire the 24V supply to the solenoid through E terminals. You’ll want to go directly from the 24V transformer to the solenoid (i.e. the Furnace should not be controlling anything yet). At this point, you should be able to turn the Humidifier on and off using the Vera.

At this point, you can use Vera Scenes or Reactor (highly-recommended for this type of control-loop scenario) to run the Humidifier when you want it to run. In other words, Furnace and fan operating, humidity is low so turn on the Humidifier. Personally I’de stop here to keep things simple by consolidating the Humidifier control logic to the Vera.

Furnace Control of Humidifier
(Optional and probably not necessary) I’m not exactly sure how the Remotec works, but I believe that the z-wave control and D controls are peers meaning, if you switch one, it will reflect the state on the other but I am not 100% certain. If that is the case, then you can use the D relay control so your Furnace can turn the Humidifier on by running the Furnace control to the D-terminals instead of the solenoid. When the Furnace “enables” the Humidifier, it will close the switch on the D terminals and turn the Remotec relay on which will turn the solenoid valve on.

In this configuration, z-wave can turn the humidifier on, the furnace can turn the humidifier on and you can manually turn it on using the button on the front of the Remotec. Because each control is autonomous, you would have to put the smarts into your Vera to do things like ensure the Humidifier is not operating without the HVAC fan. The Ecobee can tell you when the Furnace Fan is running and the state of the Remotec so you might do things like, if the humidity is high enough inside and the furnace has cycled on and the humidifier is running, turn it off. You may need to use a multimeter to understand when the furnace turns on/off the humidifier relative to a cycle (i.e. 2 minutes after heat cycle begins, 2 minutes after heat cycle ends).

Anyway, it is hard to know the details without being there with a multi-meter in hand and exactly what you want the end controls to be but I hope this helps.

#4

Thank you so much for spending the time to put that together! I agree that it will help if I step through the process with a multi-meter on the bench and see if I can get it working before attempting an install.

That’s a good point. The Ecobee does appear to have the capability of supporting a humidifier via its ACC+/ACC- terminals. I think I’ll use this as a backup solution in the event I can’t get it to work with the Remotec device. I’m a software engineer by day and I love the idea of having code that I wrote dictate what the HVAC does, so I really want to try to get this to work before I decide to let Ecobee do it for me. :slightly_smiling_face:

This is where I’m getting a bit lost. As I understand it, the “E” terminals on the Remotec device require a power source (the 24v transformer) and a load (the solenoid). Below are the 3 devices I’m working with. This is how I interpret the second wiring diagram option in the Remotec instructions:

(I apologize for the crude drawing)

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In this situation, wouldn’t the following happen when there’s a call for heat?

  1. The furnace sends 120v to the transformer, which sends 24v (red wire) to the “E” terminal of the Remotec
  2. If the Remotec device is OFF, nothing happens.
  3. If the Remotec device is ON, the Remotec closes its internal relay, which sends 24v out (yellow wire) of the “E” terminal to the solenoid.
  4. The solenoid receives 24v (yellow wire) and turns on.
  5. When the furnace stops sending 24v to the transformer, the solenoid turns off and the Remotec no longer receives the 24v signal.

Let me know if I’m missing something - I apologize if it’s a glaring omission, I just don’t wire up relays like this too often.

This is exactly why I would like the 24v transformer to “run the show” - I only want to serve as the second line of defense behind it. That way, like you said, I won’t run into a situation where I’ve turned the solenoid on with the Remotec, the call for heat stops, but somehow (Z-wave interference, Hub is offline, etc.) the call to turn the Remotec back off is never received, leaving the solenoid running for hours.

I’ve built failsafes into my code to try to prevent this, like a recurring event to turn the Remotec off that runs every 5 minutes, but I’d really like to leave this operation up to the furnace if I can.

This is really difficult to test with the furnace running, so I’ll probably pick up a 24v transformer and set up a simulation on the bench.

Again, I really appreciate your reply.

#5

A picture paints a thousand words - your drawing is perfect other than the fact that you will need to run the other yellow solenoid wire back to the second 24V transformer terminal to complete the 24V solenoid circuit.

The other thing that I gleaned from your drawing is that the furnace “controls” are 120V lines. What that says to me, is that the furnace controls actually open/close a relay to switch the 120V circuit to turn the transform on/off. Have you used a multimeter to confirm that the transformer itself is power-cycled to activate/deactivate the humidifier? Normally HVAC systems predominantly use 24V relays continuously powered by 24V transformers to open and close circuits to run the system.

I’m pointing this out because in the current configuration, you are switching the 24V side while the furnace is purportedly switching the 110V side. So neither side will work without the other (i.e. the Humidifier will only run when both relays are closed). You will not be able to turn the Humidifier on unless the Furnace has also turned it on but you will be able to override a shutoff to the Humidifier.

It sounds like that is what you want, at least for now, so I would wire things up in the steps that I outlined above except for the “Furnace Control of the Humidifier”.

Finally to be clear, this also means that Independent Controls via the D-Terminals as I originally suggested is not possible in this configuration (I thought the 24V transformer was continuously powered and that the furnace controls switched the 24V solenoid circuit - I’m actually surprised it isn’t wired in that way because that would be more standard for HVAC equipment).

#6

Got it - thanks, that makes sense. Here’s an updated wiring graphic for posterity, in case anyone who stumbles across this in the future may want to try this.

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I believe your thinking is correct. From what I recall, the transformer is patched to a terminal labeled “HUM” on the furnace board (I can grab and post a picture of this later), and that’s what provides 120V to the transformer. The two terminals for the transformer then have wire that runs directly to the solenoid, so I assume the transformer is being power cycled, but I have not confirmed this - I will do so and report back. I CAN confirm, however, that the humidifier stops running once the gas stops - I assume the furnace control board cuts power to the HUM terminals when this happens.

Yes, that’s exactly what I want! In my view, there’s no purpose to giving the Remotec device the ability to turn on the humidifier independently of the furnace, since there’s no benefit to running the humidifier unless there’s an active call for heat. I don’t mind the false positives that might arise by turning the Remotec device on and assuming that the humidifier also turns on by doing so - I can account for this in code by checking the Ecobee’s status and looking for an active call for heat, etc.

I’ll confirm this and report back, along with any other success I have in getting this configuration running.

#7

:+1: Good luck!

#8

I find this thread interesting in that most modern homes are humidty traps and as outdoor temperature drops, condensation on windows and doors starts to freeze, thus eliminating emergency exits. Also, humidity builds up in hidden places and eventually feeds the growth of mold (a health hazzard). I have my system working to remove humidity to the proper level dependent on the outdoor temperature. For example, RH of 15% when outdoor temperature is below -20F/-29C.

#9

I agree. Modern homes are typically sealed exceptionally well, which exacerbates the problem. It wouldn’t be so bad if there were smarter solutions for humidity management. The humidistat on your typical bolt-on whole-home humidifier is laughably bad at gauging humidity and making precise adjustments. They’re barely a step above “on or off” and after they collect enough dust/dirt on them, that’s basically all they are.

We just had new windows installed in our home and the last thing I want is to have them collecting condensation all winter and causing damage.

Here’s the map of outdoor temperature (F) : recommended indoor relative humidity (%) I plan to use:

"40" : "45",
"30" : "40",
"20" : "35",
"10" : "30",
"0" : "25",
"-10" : "20",
"-20" : "15"

I’ll use the Ecobee to check for both of these and make the decision real-time as the calls for heat come in. The humidifier will not turn on at all if the outdoor temperature is above 40 degrees.

#10

I have a very large open space with a panoramic winter, so humidity is higher during winter. I just bought a dehumidifier and a sensor, so I turn it on/off using automated rules based on outdoor temp/indoor humidity. It’s just set to go at 40% and it turns off automatically.

It worked very well this winter. My wife was skeptical about this, but we managed to get zero humidity on the large windows and the air is much more comfortable now. I just renovated three years ago, but if I’d go back, I wish I had installed an air extraction system as a couple of friends did. Overall, I’m satisfied, since we just have maybe 10-15 days per year with temp under 0 C.

#11

Yes, the chart is the same that I use. The challenge is not to increase humidity, but to decrease it. My ‘HRV’ is an Edenair 8000 (http://www.edenair8000.com/fr/2_2.asp) which is a heat pump in a box. This unit cools and dehumidifies the incoming summer air, and heats the dry incoming winter air with the heat recovered from the exhaust. I’ve had it in operation for several years. I do not have a humidifier associated with my forced-air furnace. My home automation system manages it automatically. Vera plays no roll in this household function.

#12

I should have given the link to the English language page:

http://www.edenair8000.com/en/2_2.asp

#13

I do have a standalone dehumidifier that I’m not using at the moment. I could probably use the same logic in my humidifier scene to trigger the dehumidifier if, say, humidity is running 30% higher than its target value for 12 or more hours. Something along those lines. Interesting thought.

#14

Sorry when the outside temperature drops to WHAT???

My freezer doesn’t get that low. Certainly, the last time I saw ice on the inside of a window was 30+ years ago!

C

#15

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