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Lots to think about -- thanks Teken, johnnyt, Xanthos & larryllix! I am more worried about underrun of heat, rather than overrun... Yes, an overrun would cost propane, but that cost is limited compared to frozen and broken pipes, etc. I also can get an email alert and remotely shut down the "unstuck" zones, with the theory the stuck-on zone will keep the house sufficiently warm (unfrozen) until I can get home and get it unstuck. Even trigger on/off the stuck zones to try and unstick it... etc... remotely. Unfortunately the radiant floor heat is the "cheaper" version, all the technology and complexity but no slab -- it is nestled in between floor sheathing (again, don't ask -- the previous owners did this). No outdoor reset. How does one work.. perhaps its something I can add? I like the idea of a dedicated ISY for this -- not to bog it down with other functions. Anyone have any luck (I know its not supported) in passing alerts/variables/messages between two ISYs? Has anyone painted the one-wire temperature sensors? Could I give them a thin coat of rustoleum to get close to matching the wall color without impacting their accuracy? Also, has anyone found a similar design for humidistats? Google searches found some pretty large *and expensive* ones, just want to check here? @larryllix - why don't you enable mobilinc to tell the house when you will return -- 24 to 48 hours out? Is there a reason you opted to not use the "remote" feature? I don't use the subscription, rather I configured it without their subscription gateway. Thanks again! 50/50

Very interesting. Let me test my thinking. a) I will leave the existing dumb thermostats in place for my "oh crap" scenario. Ie. the network router, ISY or the Autelis bridge go belly up and no one is home. Just set them to the absolute minimum desired temperature... say 55 F. This will let the system work "as originally built" if a room temp falls below 55. It can also serve as a "Manual Override" if I am away or unreachable, and the boss needs heat, now! Install 7 x one-wire temp probes [next to each Tstat], connect to the Autelis ISY bridge, pump temps into ISY. Add an additional probe to the boiler hot water feed to know if the water distribution system is "pre-heated". c) Install 7 x IOLincs next to my heating zone controller (pic of one attached), wire them in parallel with the Tstats N/O (Normally Open) on the 24 VDC HVAC circuit. d) When a Tprobe fits my logic (primary zone, 2 degrees under setpoint, etc), close the corresponding IOLinc until the Tprobe is satisfied, then re-open it. For secondary zones, use logic to determine the manifold in use, actual temps vs. target for each room on that manifold and its priority, and if the system is already hot before closing the IOLinc, re-open when satisfied. e) get fancy with the ceiling fans, etc. In fact, I could experiment with heat/cool times with and without fans to find which one really does help more, normalized to outside temps (fans move air, moving air is "cooler" to the body than still air, does that make the boss want the setpoint higher? Or do the fans make the room temp more "stable" and therefore more comfortable, while cycling the heat less?) f) figure out cooling later, but use the same Tprobes. g) investigate if there is a way to do a 7x N/O IOLinc without 7 large boxes, integrated switching transformers, etc... Maybe Elk? Note I have no Elk today and not sure how the costs add up. Cost: $130 for Autelis bridge + maybe $100 for probes + $315 for IOLincs + wire and time... or $550 plus wire... beats $1,050 for 7x2441TH and since I only have two conductor bundles to the Tstats (don't ask.. I really shook my head in disbelief at this!), I need to run new wire anyway. Anyone see any issues or drawbacks with this idea? I assume I will need to run Cat5/6 for the digital Tprobes ).. and not just regular Tstat wire? (Teken, I will likely do humidity at the same time as you did... just makes sense.) Thanks much! 50/50

Okay, need your expert advice on feasibility. My house has 7 zones for heat, two for cooling (2 of the 7 control two A/C units as well - north half/south half). Existing Tstats are of the "independent and dumb" variety. The heating season is coming and I need to save fuel. Propane. $3+/gallon. 1,700 gallons consumed last year. New house (2006), well insulated, but the boiler ran almost continuously because each zone is completely independent... and they are rarely, if ever, in sync. 4 zones are radiant floor heating (hot water) + 3 zones are hot water baseboard I have an ISY and 40+ switches/iolincs/motion/etc. ISY is my preferred method for Tstats. Willing to consider other options, but they need to be easier or cheaper than the ISY setup. The zone controller brings all 7 zones into 3 circulator pumps that drive manifolds. The manifolds have zone valves like this: M1: Radiant floor: z1: Kitchen & dining -- the whole manifold is one zone == (1 Tstat) M2: Radiant floor: z2 - Living Room (+A/C); z3 - Main Bath; z4 - Master Bath == (3 Tstats) M3: Hydro baseboard: z5 - master Bed (+ A/C); z6 - Second bed; z7 - Third bed == (3 Tstats) There is an 8th zone (4th manifold) for domestic hot water. Got it? Simple enough? Due to the complexity of the setup, when just one zone calls for heat, a lot of pipe needs to heat up. What I really want to do is intercept the call for heat and modify it in the ISY... by creating logical primary zones and secondary zones to make this more efficient (using thermal mass / restricting run time of the boiler). Example 1: weekend daytime: Living room and Kitchen are the primary; bed3, main bath, master bed, master bath, bed2 are secondary (in that order). Example 2: weekday daytime: Living room, Bed3, Kitchen are the primary; main bath, master bed, master bath, bed2 are secondary (in that order). Example 3: nighttime: Master bedroom and MBath are primary, then kitchen, living, foyer are secondary (in that order), bed2 and bed3 are off unless guest is in house. -> No zone can turn on the boiler except current logical primary zone(s), they trigger at 2 degrees under setpoint -> When a primary calls for heat, and a secondary zone on same manifold is under its setpoint, heat both (eg. living room and main bath) until each satisfies -> Attempt to only circulate to 1 manifold at a time (except M4, which is independent) -> When the requesting primary is satisfied, the other primary is checked for delta to setpoint, if >= 1 degree difference, heat that (follow same rule for 2ndary zones on same manifold) -> After all primarys are satisfied, follow a pecking order for secondary zones based on weekend/weekday/guest in house (bedrooms 2 and 3 are guest bedroom and home office, respectively) -> Emergency override if any zone falls below 55 -- heat immediately -> (future**) If domestic hot water sensor is "hot", check zones in order and "heat to satisfy" if current temp <= 2 degrees below setpoint -> (future**) force boiler off, circulate to last unsatisfied zone for <time> or until domestic hot water sensor is "cold" -> (future**) indicate the dist. infra. is hot on a KPL -- time to run washer/dishwasher/take a shower. ** Note the domestic hot water (M4) has a flow valve with a temp sensor (Taco I believe) in it already, I need to figure out if I can tap into this with an IOLinc. The sensor will go hot when a heating zone is calling for heat and the distribution infrastructure heats up, even if the domestic hot water is not being used. So.. am I nuts? Can I do this in an ISY? Is it smart... what if the ISY freezes up when no one is home (its been really, really stable)! Can I "make it safe" on the condition of a failure of the ISY? To keep domestic tranquility, I'd like the Tstat to show its current setpoint and the actual temp on its display, and if the Tstat is manipulated, for the ISY to recognize it and continue on... (current temp vs set point). Possible? Thank you! 50/50

Looking to cover 6 heating / 2 AC zones.. and optimize flash burner usage based on room occupancy and priority. Looking at NEST, but for $1,500, I'd expect to be able to play and optimize as I need for my complex system. Is there a list of compatible 'stats with an ISY994i? Thanks! 50/50