Venmar (Vanee/Broan) ERV / HVAC controller output

[k-d]

Had a chat with tech support for Broan today - he said they were unwilling to share the specs of the serial communication, but I might give Venmar a shot next given they seem like the actual business unit that manufactures these things.

They did explain the PER/DIS split to me - basically PER will allow positive pressure, and DIS will allow negative pressure. So I think PER is what I want for my use case (minor amount of “make up air”) in OVR mode.

Edit: Venmar was not particularly helpful on attempt #1 either… I’m not sure if it’s even possible to reach the department that would have this info over the phone…

[fett]

Need that too

[k-d]

Got the dry contact relay hooked up to the OVR port today with a Shelly 1 Plus and started playing around with it. For some reason it was missing on the online manual, but in the print manual it basically said to pass 12V across any relay and back into the OVR port. This was non-obvious to me at first (vs wiring up the Shelly some other way). Bonus: Shelly 1 Plus can be powered by 12VDC pulled off the ERV.

Now I’m considering another one, or maybe a 2-channel relay, because the dry contact can be set to put the unit in intermittent mode (good for if nobody’s home vs running all the time, I think?). Though I’m wondering if 12VDC will work there vs 24VAC given it’s expecting wiring from a thermostat…

I did confirm that DIS mode is not what I wanted, it’s entirely negative pressure when I looked at the live airflow on the device. So sticking with PER mode.

[Foosman]

FYI – I gave up on Venmar, and decided to things my own way. I simply bought a switchbot on the wall switch as the control of the switch. I then bought a power meter and plugged the HRV into it. (and used the power levels as the feedback) creating a feedback loop for whether I’ve achieved the desired power setting. I’ve found the switchbot lasts a few years, so replacing a battery now and then isn’t too big a deal.

Anyone else come up with something more elegant than this?

[k-d]

What are you trying to do and which model do you have? My Shelly 1 Plus on the OVR port works well enough. If you have a set of contacts of any kind, you should be able to control it with a relay - how much control you get depends on model I assume.

[k-d]

I did play around with the “Vent” wiring (dry contact) this past weekend. It actually worked great with 12VDC - I could set an unbalanced MAX setting and it would use it when the contact was closed. However, as the manual states it completely overrides the wall control. Once the dry contact is opened back up, the ERV is forced back into Standby (off) mode - the only way to get it back to the previous state is using the wall control again which is a nonstarter for me.

However, I discovered that using the VTTOUCHW you can set “Auxiliary” airflow CFM. It doesn’t allow for supply/exhaust independent settings, but if you set it as low as it’ll go and use “Performance” Mode you can end up with a small amount of positive pressure when the OVR contact is closed - which is exactly what I’m looking for. In my case it was ~60CFM which is enough to help exhaust fans work well!

I have noticed the airflow settings on the VTTOUCHW don’t seem to stick sometimes though, not sure why they keep getting reset. Anyone else with this device observed this by chance? Wondering if it has to do with my wonky wiring.

[aegli214 (Andrew)]

I just ordered a similar ERV, and I’m thinking about doing the automation a different way. These ERVs are compatible with the “automatic control” module, which lets you flip through a few basic modes with button presses. Details found here:

https://www.vanee.ca/en/products/accessory/95-automatic-control.html

The control module is pretty cheap (~30.00 USD). I’m going to attempt to open it up, and “emulate” the button presses from an ESP32 with a relay. The one button lets us cycle between these modes:

• Click 1 = RECIRC (if available)
• Click 2 = INT
• Click 3 = MIN
• Click 4 = MED
• Click 5 = MAX
• Click 6 = OFF

I think it would be fairly easy to pop the front button cover off and connect either side of it to a relay such as this:
https://www.aliexpress.com/item/1005002867727977.html

Then connect the other side of the relay to an ESP32:
(Can’t post the link because I’m limited to 2 links as a new user)

The ESP32 can then cycle through the modes by simply doing an emulated button press, based on CO2/VOC readings from sensors around the house, or whatever other system you wanted. Seems fairly simple, no? Let me know if anyone sees any concerns with this. My plan is to eventually drive many parts of my HVAC system (air handler, furnace, heat pump, dehumidifier, ERV, HEPA) all off the same ESP32, with inputs from air monitors placed around the house.

[k-d]

This seems clever, I’m curious how it goes for you! Especially vs something like a switchbot. I read somewhere that these basically worked on setting difference resistance levels, so that might be something to investigate too.

On my OVR connected to the relay I noticed that the time I close the contacts seems to switch between two modes (20 minutes and continuous), so there might be something to that too.

Personally I still like having my controls working without smarts if something goes wrong, which is why I was looking at complimentary solutions.

[Foosman]

Gents,

I may not have explained it as clearly as I could have – I have things working much better now. I have things pretty well automated with all the features that @k-d was wanting.

The key was to have a solid feedback control so you know the HRV reached the state you are asking for. Ironically, I already had the Venmar smart controller that was described above. I finally got a chance to sit down and take a picture so you could see it for yourself. I have a ton of ESP8266s around the house, but in this case, since the addition of the Bluetooth proxies, I have amazing performance with the Switchbot, and ask you all highlighted, i still want my finger to be able to reach up and manually command the HRV.

Figure 1: My setup, (there is an extension cord that happens to hide the Power Meter that the HRV is plugged into).

The problem that I solved is the feedback system to know the state that the HRV is in. (ie., did my command achieve the desired effect. Well, I achieved that by attaching a powermeter as the power source for the HRV. So I can see the power drawn by the HRV, and can use the power level to map to commanded state.

For example,
3 W (+/- 1 W) = Off,
25 W = Min
51 W = Med
78 W = Max

So, as you can imagine, this was a classic use of a state machine, because the switchbot has to reach the desired command by cycling through the various states by pressing buttons to move in one direction through the statemachine. For a while, I thought about adding two more additional switchbots to command TURBO and AUTO, but because I already have the system designed in HA to feedback on both interior Particulate Matter and CO2, rarely does the system ever need to get to Max. As people come and go, the system brings the CO2 down, and goes from Max, to Med, and to Min, etc. (the only problem, is that going DOWN requires half a dozen button pushes, but because there is a built in dwell timer in the Venmar control, it doesn’t mistake the intermediate states as actual commands). The good news, is that when there is a sudden source of pollution, the system reacts going from Low to Med to High because it only takes one or two switch bot “clicks”. I also have this integrated into my Ecobee, so I can also push one the circulating fan to also filter the air through our very effective American Standard filter.

Also - get this, as I’ve owned this thing for nearly a year with this arrangement, I’ve been able to detect when my filters are getting plugged. I’ve only done this by visually checking how much the power in a given state has creeped up → but I can see making that more robust a future project. (I also started hand making HEPA filters because the MERV filters from Venmar are a ripoff where I live. I was able to build a bunch from one 3M filter.

Anyway, I’m really happy with this, so I’ve started to tear up my Node Red code, and use some new state machine blocks I found throughout the community.

In closing, I think within another year we can have a really robust integration of these Venmar HRVs despite the company being unsupportive.

Figure 2: One of my summary dashboards showing the Air quality control system.

The SCD30 is in the basement sauna, the Portable CO2 is a box I made to take to various locations that is on our top floor. The system controls off the Average (light blue).

[Foosman]

Did your HRV arrive yet?

[k-d]

Nice! Glad that seems to be working well for you.

@Foosman

So I can see the power drawn by the HRV, and can use the power level to map to commanded state.

For example,
3 W (+/- 1 W) = Off,
25 W = Min
51 W = Med
78 W = Max

Have you noticed that this power stays consistent? My ERV will fluctuate sometimes regardless of what mode it’s in. My MIN mode actually draws more power than my “medium” unbalanced/slightly positive pressure mode which I thought was strange. I was considering putting some CT clamps to measure each fan individually but that seemed like overkill…

I guess as power draw increases at the same setting, you can tell your filters are plugged after a certain point?

@Foosman

I also started hand making HEPA filters because the MERV filters from Venmar are a ripoff where I live. I was able to build a bunch from one 3M filter.

Ha, I thought the same thing and ended up adding an inline filter box (CFB series from HvacQuick) due to this cost and removed the filter in the ERV. Fits a 14x14x4 filter for greater dust holding capacity, lower pressure drop, less filter bypass hopefully (my ERV core was getting pretty dirty), and I think I can get a MERV14 from Nordic Pure - haven’t found anything better. Insulating it was the fun part, used styrofoam and can foam but I think it came out OK!

[strikeir13]

I’m also interested in the discussion and potential reverse engineering projects here. I’ll share what (little) I know and have found, as well as my ERV/controller setup.

I have a Broan ERV, model ERV200TE. It’s part of the Broan HE series which has corresponding Venmar and VanEE models as listed below:

• Broan: ERV200TE, ERV250TE, HRV200TE, HRV250TE
• Venmar: X24 ERV ECM, X30 ERV ECM, X24 HRV ECM & X30 HRV ECM
• VanEE: G2400E ECM, G3000E ECM, G2400H ECM & G3000H ECM

All of these models have a single Broan/Venmar/VanEE controller listed as their only compatible controller:

• Broan: VT9W
• Venmar: X-Touch Mod. no. 40455
• VanEE: Gold-Touch Mod. no. 40355

This controller has 4 wires, Y/B/R/G. A 2015 post in a separate home automation forum identified a different 4-wire controller from the same manufacturer with B as ground, Y as +12VDC, G as control, and R as unknown. That post also stated that the unit was controlled via resistance between the G and B terminals. Unfortunately, that doesn’t seem to be the case for the VT9W model as I tested a number of resistors between the G and B terminals and none of them had any effect on the ERV. My guess (/hope) is that these 4 wires are similar to the D+/D- configuration listed previously in this thread and that methods to reverse engineer that communication could work for my unit, as well.

The VT9W controller has a “Smart” mode that relies on outdoor temperature and indoor humidity to regulate exchange speed and damper operation. This works fairly well (though I would prefer more configurable control) except for one concern: This summer, the outdoor PM levels have gotten dangerously high at times due to Canadian wildfires. Awhile ago, I confirmed with Broan technical support that cutting power to the unit would leave the dampers in whatever state they were in when the power was lost, which means that using a smart switch wouldn’t work to block PM ingress. For now, I’ve also resorted to just using a Switchbot to manually toggling the Menu button multiple times in a row in order to cycle the unit to the “Off” mode that closes the dampers. I’m similarly using a power monitoring smart plug to verify which mode the unit is in (esp32 is monitoring indoor humidity to verify unit operation, too).

I’m not thrilled with the Switchbot approach because there doesn’t seem to be any sort of confirmation available that the “press” message gets received and executed. For my scenario, since I need to press the Mode button multiple times in succession, if any of those presses gets missed, then the state of the ERV effectively becomes unknown to Home Assistant until I go down to the unit and manually correct it.

In recent years, Broan has introduced a “Overture” system of sensors and controls, some of which are listed as compatible with my ERV200TE model. However, when I looked into it more, I found that the “compatibility” is simply via the high-speed override option. Here’s the wiring schematic for the Overture system smart plug:

My unit matches the bottom diagram, but both work the same way - closing the circuit between the OC/OL or 12V/OVR terminals turns on Turbo/high speed until the circuit is broken again. I may look into achieving the same thing with a Shelly1 relay (which could also be powered by the 12V from the ventilator). This method is only an override, however, because the unit reverts to it’s previous operation when the circuit is broken, so this option is pretty limited.

All I really need is a wired, non-Switchbot method that turns the unit on to low speed and off in such a way that the dampers are closed when off. Between that missing piece, the Shelly1 override option, and the smart plug power monitoring, I think I’d be covered, but unfortunately, I haven’t found it yet.

[k-d]

All I really need is a wired, non-Switchbot method that turns the unit on to low speed and off in such a way that the dampers are closed when off. Between that missing piece, the Shelly1 override option, and the smart plug power monitoring, I think I’d be covered, but unfortunately, I haven’t found it yet.

If you are OK with the options being “off” or “min” you should be able to do that via the HVAC contacts - if you close the “Vent” contact and the unit is configured appropriately it goes into min speed mode, and if you open it up it goes back into standby.

Downside is you can’t get back into “Auto” without interacting physically with the device, but maybe you can mitigate that with the Switchbot? See my post here: Venmar (Vanee/Broan) ERV / HVAC controller output - #18 by k-d

[strikeir13]

You’re right, though I think the override goes to “max” speed rather than “min”. Most of the time, I’d want the unit continuously circulating at low speed with high speed only used for specific situations.

My setup now is technically workable with the Switchbot but I’m definitely interested in something better, I just have yet to find it.

[k-d]

You’re right, though I think the override goes to “max” speed rather than “min”

I think this is configurable, at least it is on my unit:

Unless you are talking about OVR - which is also somewhat configurable:

[strikeir13]

Ah, this must be a difference in capabilities then. Commenting the OC/OL terminals on my unit sets it to high speed only, no other choice.

[strikeir13]

After testing the Switchbot approach, I’ve determined that it won’t work for me and my ERV200TE unit & VT9W controller. Cycling through the various modes doesn’t necessarily change the wattage draw since some modes may not immediately activate the blowers (e.g. 20 min/hr & Smart). Plus, sending repeated commands to the Switchbot is a pretty bad experience because they don’t seem to queue and some will drop unexpectedly, leading to a very unreliable experience. So I’m back at square one - able to call a Turbo/high speed override with the OC/OL terminals, but no way to reliably manually turn the unit off or to low speed.

[matthewjtrotter]

Hey folks, I’m new to home assistant and am just getting started with the platform and I’m getting close to putting some time into getting my Venmar AVS integrated. I’m going to use this thread to capture my thoughts and maybe give some ideas to those also fooling around

I found this document which may help.

VCES-DDC-IOM-1-PN-500020459.pdf

It looked like some folks were trying to hack the serial communications. I was doing some cursory research and it looks like there is a protocol called BACnet which ASHRAE defines for building automation and control. Reading some docs on this got me think why enginner a new solution for your consumer product?

I am wondering if the device uses BACnet over RS485 serial. The BACStat II controller uses a very similar 4 wire configuration but on 24v. And it has a Net+ and Net- terminals.

Needless to say, I going to dive into this once my renovation settles down. I appreciate the work other have done researching and digging.

[k-d]

Great work, thanks for sharing this! Using something that’s modbus-like but not quite modbus would align with my earlier investigation here: Venmar (Vanee/Broan) ERV / HVAC controller output - #9 by k-d

Doing a little searching for BACnet-related libraries and found https://bacnet.sourceforge.net/

I also found this tool: https://optigo.zendesk.com/hc/en-us/articles/360033989832-Visual-BACnet-Capture-Tool-for-Windows-Quick-Start-Guide. Which may be worth an attempted investigation. If I get bored, I may take a look myself as well.

[matthewjtrotter]

I also think it’s interesting that the Advanced Wall control has a Bluetooth Low Energy chip in it but there is no mention of it in the manuals anywhere