Viewstats... Worth the Headaches??

TurnipTruck

Greetings,

I have started using Viewstats on my last two big resi projects. Needless to say, they are by far the most finicky, least reliable piece of equipment I've ever integrated into a system.

Has anyone been particulary impressed or unimpressed with these things?

glr-fti

After 10 years of trying all sorts of different thermostats and working with many different HVAC units and contractors I have come to the conclusion that now I will only provide a Cat5 to the HVAC location and let the contractor put in a system that will work with me. If it doesn't work I don't integrate it. I don't want the hassles if HVAC equipment fails and I get the middle of the night call. The contractor just unplugs my cable and I am then out of the loop. The manufacturers are at least now starting to cooperate and eliminate all of the proprietary hardware and play a little nicer.

To answer your question, I guess I am unimpressed.

TurnipTruck

On this latest system I am working on, I have 17 Viewstats. I've come to understand that they WILL lock up at some point no matter what you do.

It's a shame, but I had to put a watchdog relay on their power. If there are no strings from the virtual device for thirty minutes, the relay pulls the power to all of the stats for a few seconds to bring them back to life.

Lessons learned.....

sonny

I have switched to the Proliphix brand. They have a webserver built in and have a built-in 365 day calendar. I have a basic Duet module written that I am continuing to build upon. When I get it done I'll post it.

DHawthorne

I have probably more than a dozen Viewstat jobs out there. My experience is that once you get the kinks out, they are a reasonably solid product. I've had one or two projects when getting said kinks out was a major nightmare though, and that has some weight to it. I wouldn't say I was impressed with them ... it's more like I've found a way to work with them, and I haven't found a product that is better.

TurnipTruck

Hi Dave,

What sort of kinks have you ran into?

DHawthorne

TurnipTruck wrote:

Hi Dave,

What sort of kinks have you ran into?

Mostly hardware kinks. Far and away is the rolling reset issue they get when they are confused. I've had this happen due to improper furnace connections, and defective disty boxes. Pretty much anything they don't like makes them go into a reset cycle.

The other kink, which I have eliminated in code, also resulted in runaway resets, but it was due to too-frequent polling (at least according to Aprilaire). I was using legacy code based on the fact that older Viewstats didn't report asynchronous changes properly; but the new ones do, so I scaled the polling way back and haven't had a problem since.

Something that is really important with these beasts is that you have to go into the setup of each stat and make sure they total mount of stats in the system is properly set. Don't pad it, don't skip addresses, and don't leave room for future stats. If you have 7 stats, set it for 7! The reason is it manages the 422 buss by waiting for all the stats to report back - and anything "missing" from the buss, it's going to wait for. Left at the default of 32, it's going to wait for all 32 to report even though they don't exist. It will timeout, but the waiting period makes the whole buss unresponsive. Too much of that and they start resetting.

TurnipTruck

What is the 24 volt AC current consumption of each stat? I have not yet had a chance to test and find out for myself.

On the system I am having trouble with, I am having a stat lock up on the order of once a day, killing the bus. I have been using my rebooting relay to bring the system back. No particulat stat, it could be any of them.

As of now there is no distribution panel. All stats home run to 110 punch blocks and are bussed together there, connected to an NXI serial port. It is my understanding that the disty panel does nothing more than what I am doing, but gives you the ability to pull stats off the bus more easily.

DHawthorne

TurnipTruck wrote:

What is the 24 volt AC current consumption of each stat? I have not yet had a chance to test and find out for myself.

On the system I am having trouble with, I am having a stat lock up on the order of once a day, killing the bus. I have been using my rebooting relay to bring the system back. No particulat stat, it could be any of them.

As of now there is no distribution panel. All stats home run to 110 punch blocks and are bussed together there, connected to an NXI serial port. It is my understanding that the disty panel does nothing more than what I am doing, but gives you the ability to pull stats off the bus more easily.

Max surge current is 2.0 amps ... which is pretty dang high really.

The disty panel definitely has circuitry to buffer and help manage the comm buss, plus the ability to pull them off said buss at will, as you mentioned. But it is definitely not just a dumb termination block. I would strongly recommend starting there and putting on in place of your 110 block.