I have used a ton of the redlink wireless zoning on retrofit. The issue I have with their dampers is not of quality, but that the actuators are bulky and much more complicated than the aprilaire's dampers. When aprilaire/lennox came out with their new dampers with the external position indicator it really helped me do mostly aprilaire dampers when they have the sizes we need. Also, aprilaire has a slick retrofit 6" damper that is inexpensive (less than $30 wholesale) and has a very low actuator profile and simple, simple installation. We do tons of retrofitting on existing basement system that use rectangular main plenum (below the ceiling joists) with lateral runs in 6" (which is 99% of our market). A typical installation requires 20+ individual retrofit dampers, and then you group the dampers into zones.
From there, we used the variable speed Lennox Furnaces, that allow for adjustable air flow to each zone. Each zone can be adjusted in 10% increments starting at 25% of total air flow up to 100% of air flow. Example: on a 3 ton/1200 cfm furnace blower (Lennox Only does this), minimum air flow is about 300 cfm. Air flow can be adjust in 10% increments for EACH zone.
With the advent of Lennox's modulating furnaces, it's a perfect match. The tricky end is the Air conditioning. Currently, the nicest A/C unit Lennox makes is only a 2 stage, and only cuts to a 2/3 capacity on first stage, so it will cycle the a/c. BUT.......Lennox is coming out with a full modulating A/C unit, and that will allow for the A/C unit to slow down matching indoor air flow.
At the end of the day, we use a combination of 3 or 4 different brands of zoning depending on the actual circumstances. In this case here on this forum, the best option is to just spend a bit of money on actuators.
On really high end installations, where no bypass is wanted by the client, and being quiet is key, we use a really nice 99.99% sealing damper with external actuators. My cost on that type of damper setup is almost triple, and its much more complicated to install.
Have you done any Arzel zoning systems? Nice setup for retrofit, dampers are controlled by air pressure instead of electric. They also have an interface to run it with a Harmony III board.
I'm waiting for a new zone control designed to work with the icomfort thermostat, I really like the icomfort compared to any other stat but it ***** that you can't offer it with a zoned system yet.
No, i havent had any experience with the arzel product. Just googled it, looks interesting. We dealt with a air bladder system one called "my comfot zones" and i hated it, and for what it was, way over priced. The advantage of it was you could completely retrofit it from the mechanical room and the registers. No cutting, no fishing wiring. The arzel damper system still has external damper actuators, so in a retrofit application, its going to require sheetrock access panels at each damper if the ductwork isnt setup for zoning. I imagine the cost is exponentially more than the lennox/aprilaire dampers. $30 for a 6" round retrofit damper (and they seal really nice) is tough to beat, and i doubt the arzel dampers have any ability to set for bypass (so they only partially close).
As far as the IComfort, having been a zoning contractor for years, we are used to not having smart thermostats integrated into zoning. Carrier/bryant have always had it, but ive never been a fan of how the system functions. Even when the icomfort is integrated, i dont see selling it because most of the homes we do on new construction have full home automation, and the builders hate large thermostats, and demand that the hvac be accessed through the control system (control 4, crestron etc). So unless the smart thermostat can communicate through rs232 signal, we are toast, and its a liability to sell the home owner on it.
I just wish the harmony had the ability stage airflow (especially in heating) in individual zones. I have even toyed with the idea of switching the piab terminals with a relay to change airflow based on thermostat needs. It will be interesting in a few weeks to see what Lennox introduces. Word is, modulating 25 seer, with icomfort zoning......now how it does it, and how flexible it is for how we apply it, thats the big question.