Air Exchanger Control Protocol

elperepat

New Member
Hi!

I'm planning to do some automation of my air exchanger. I'd like to control when to exchange/recirculate air and when to switch speeds. I googled around but couldn't find any information concerning the communication protocol between the exchanger and the control unit.

My air exchanger is a Venmar, but from what I can see, vanEE is the same thing.

I think it must be pretty simple. I think it's not hardwired, because of the quantity of modes to choose from (off/min/max + damper opened/closed) which would require 3 wires, + 2 for suply/ground for the leds. There are only 4 wires between the unit and the control. I guess they are using something like RS-485.

Did anyone of you see any info regarding this on the web?

Thanks

Patrick
 

politics123

Active Member
Hi Patrick --

I'd think it highly unlikely that the unit is controlled through RS-485. Most likely, your cabling is:
power, common, damper control, speed.

These are Low voltage cables... shouldn't be to difficult to sniff out which does what.
 

elperepat

New Member
Thanks for your input. That's what I'll do. I just wanted to know it someone had already done it.

I'll post the results shortly.


Patrick
 

aktim

New Member
Patrick,

I have an Venmar HE2.6 and wish to automate it also.

My goal is to have the Ultima controller attach to my RCS C48 Controller which in turn controls the HE2.6. That way I can either use the Ultima or the controller as the input.

If there is a speed control, I'm interest in how you plan on implementing that. I just have IO Relays. I guess I could divide the voltage and relay the appropriate voltage level based on high or low setting.

Although RS-485 would be sweet, I'm also betting it's just voltage controlling since you can also buy just a mechanical on/off controller for the Venmar

Thanks,
Tim
 

darryl

Member
I have a venmar constructo 1.5 or 2.0. I took apart a wall control once. There's a simple push button and led inside. Push the button and you get 20 minutes of high speed air exchange. The main wall control has two modes high and low.

Also directly on the unit there's a toggle switch right on the unit. High/low/remote.

In both cases I think it would be reasonably straight forward to insert your own controls. My long term goal is to automate air exchange based on indoor humidity in the winter.

Your mileage may vary depending on the particular model you have.
 

JonR

Member
I too will be paying attention to this thread. We will have an ERV in our new home that I'd like to be able to automate. For one, I'd like to be able to activate the ERV at full speed if any of the CO detectors go off. I also want to control the system based on outside temp/humidity and whether any windows are open.

JonR
 

Gabeloooooo

New Member
Any news on the protocol. I'm planning on replacing the stupid Altitude controller for venmar (which is a big piece of garbage by the way) and make my own.

Any luck? Otherwise I'll just get out the old oscilloscope and research it the old fashioned way :)
 

tmbrown97

Senior Member
Instead of reinventing the wheel, are these systems compatible with normal off-the-shelf thermostats? If so something like an HAI or RCS thermostat would be a quick and easy one to get online, with a well published protocol and built-in support in most HA systems. You just need one that supports the right number of modes.

In the case of the RCS, you change out the zone controller and the thermostats - as it uses proprietary wall-units that will run off just 4 wires; then all the magic happens in the zone controller which is mounted at the unit... and that's where you'd interface with the RS485 protocol to interact with the thing.
 

Gabeloooooo

New Member
Has anyone had any luck sniffing out the protocol?
 
I have to start looking into this more, since the venmar controls are insane. The intermittent mode only has max setting, no way to alternate between min vent/ min circulation. Junk.
 

ano

Senior Member
I am thinking about getting an air exchanger and was wondering does it allow you to electronically control if its used or bypassed?  My impression was you had one or you didn't, and there wasn't a way to have it NOT exchange the air.  Is that true?  The reason I ask, is I heard that they are quite low in energy efficiency so I would bypass it when the temps were pretty high or low, but only use it when outdoor temps were close to inside temps. 
 

signal15

Senior Member
ano said:
I am thinking about getting an air exchanger and was wondering does it allow you to electronically control if its used or bypassed?  My impression was you had one or you didn't, and there wasn't a way to have it NOT exchange the air.  Is that true?  The reason I ask, is I heard that they are quite low in energy efficiency so I would bypass it when the temps were pretty high or low, but only use it when outdoor temps were close to inside temps. 
 
These can all be hooked up a number of ways.  Mine is set up to draw air from a vent in the kitchen and dumps that outside, outside air is drawn in and dumped into the supply plenum on my furnace.  They can be set up to draw from either a room or ductwork, or dump fresh air to a room or ductwork.  Mine has no "bypass" because when it's off, no air goes through it.  
 
Energy efficiency on mine is around 70%, which isn't terrible.  I usually have it on 50-100%, regardless of the outside temp.  
 
Mine is made by this company:  http://www.renewaire.com/
 
Also something to note, Fresh Air Exchangers/HRV's are *code* here in MN since the late 1990's.  If you're house was built after that, it has to have one.  The air quality in my old house that didn't have one was very poor compared to my new house.  They really do make a significant difference.  Also, if you're getting condensation on your windows in the winter, these can be used to reduce the humidity in your house to prevent that.
 

ano

Senior Member
I think the efficiency can sound better than it is.  Lets say its 70 inside and 110 outside.  If it was 100% efficient, the best it can do is cool the incoming air from 110 to 90 because the outgoing air is also going to be 90.  So you are sucking in 90 degree air instead of 110 degree air, but if you didn't have one you would be sucking in 70 degree air.  That is why I wondered if you could bypass it.
 
I'm looking at going a slightly different route. No air exchanger.  Instead i will have a damper I can open to draw in outside air and exit inside air.  I would only open it when the temps were right. Like yesterday.  It was cold over night, and in the morning my house was about 70 so my heat went on.  But outside I think it got to 78 degrees.  Why not bring in outside air rather than using heat.  We have the opposite problem as well where the house is warm, but it cools down overnight.  Plus the quotes I was getting on the air exchanger was around $1600.  So maybe my solution won't work good when temps are high and low, but it should help.
 

42etus

Active Member
Ano, the logic in your example is flawed. If it is 100% efficient, all of the energy contained in the incoming air would be transferred to the exhausted air.  There would be no loss of energy and the incoming air would be at 70°
 

signal15

Senior Member
Ano, the logic in your example is flawed. If it is 100% efficient, all of the energy contained in the incoming air would be transferred to the exhausted air.  There would be no loss of energy and the incoming air would be at 70°

Ano, this man speaks the truth. If it was 90,then it would only be 50% efficient.
 
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