Wikipedia: "Wind is the roughly horizontal movement of air (as opposed to an air current) caused by uneven heating of the Earth's surface." [Edited to delete comments re: checking your facts.] "If birdwidow studied the air flow with a smoking-pipe, that is far more compelling than someone's unqualified opinion." I'm not arguing that air doesn't flow through her greenhouse. [Edited to delete comments re: unqualified opinion] Look, here are the reasons I would give for not moving air in a greenhouse in the circuit suggested by Birdwidow. 1) As stated by Mylu, we are trying to mimic the effect of Mother Nature, and by far the most significant air movement effecting plants is wind, which is generally horizontal. 2) Using ceiling fans, the circuit moves air up one end, across the top of the GH, down the other end, and across the floor. Our goal is to move air through the canopy of the plants, for all of the reasons described in the HAF link above; think about where the canopy of the plants is. It is not along the floor or the ridge. It is generally at working level, at the level at which HAF fans are placed. 3) Many, perhaps most greenhouses have a ridge vent. How does this air flow circuit perform when the ridge vent is open? I don't know, but I suspect it is at least somewhat less efficient, because air will be draw in and out through the ridge vent. The air flow across the ridge of the greenhouse would then be reduced in proportion to the amount of air the fans exchanged through the ridge vents. This also could impair the ventilatory function of the vent near the ceiling fan blowing the air down. Maybe this is accompanied by a commensurate increase in ventilation from the other fan...but maybe not. 4) It seems extremely unlikely that air movement through the plant canopy is as effective when vertical, around a bench or container, as it would be moving vertically. 5) A ceiling fan would be he** on my bananas. Ceiling fans may be an attractive option in some circumstances. A ceiling fans system may be less expensive that a tradition system of GH HAF fans...won't argue that. Ceiling fans might be considered more efficient to run, or more attractive, or whatever. Certainly, as I stated above, some air movement is better than none. But I bet you would have a hard time showing equivalence between the general application of a ceiling fan system and a standard HAF system. It would make a nifty experiment. SB

Integrating unmatched systems with different circuit boards and especially two transformer systems is never easy. Sorry to say, not knowing more about the whole system including how the heat pump changeover and controls operate, I doubt you will get an answer on this. Based on my past experience on instances like this, it would take all the wiring diagrams of all the components, a lot of scratch paper and an hour to figure it out to assure everything integrates and nothing burns out before making the connections. In addition, sometimes without fossil fuel kits, additional sensors are involved. "C" is a common, many times for the stat to power lights, indicators, screens, power unit so that the batteries are back-up only and on occasion operate additional accessories, including the remote if you have that option.

Only the light switch needs to be at both locations and frankly, unless you have some goofy local code or this is a stairway, there's no requirement for even light switches at both entrances to a room. Almost every fan I've seen can have the motor and the light controls split and you can put the latter on a three-way if you like. The reason the instructions don't tell you to put the surge suppressor on an oversized breaker is because there's no point in doing so and it is ILLEGAL. Do not use a large breaker than the ampacity of the wiring connecting it. Most of the ones I've seen you do not put on a larger than 20A breaker. Having lost phones and del modems and a well pump, I believe on putting surge/lighting protection on everything I can find. These suppressors are cheap "insurance". Yes, there is very MUCH a limit on the number of wires in a given box. It's called Box Fill and a bigger discussion than I can type into this box. Get a good electrical book (Wiring Simplified is one) or google box fill. You protect the feeder from the main panel to the sub panel with a breaker appropriate for the wire. It matters NOT what the rating of the sub panel is. #2 is appropriate for 100A breaker on copper type NM, You can protect #6 with a 60A breaker for type NM. Other wire types may have different ampacities. Your heaters are NOT in series. Again you need to size the breaker for the wire. You must protect 12-2 NM with a 20A breaker (or smaller). I'm assuming we're talking about 240 V heaters? If not you're math is way off. If you're using 240, the 20A breaker and 12-2 is fine. Most home center employees including this one is a complete idiot and dangerous. NO, YOU CAN NOT put breakers into a panel for which it is NOT listed for. Yes they may fit and may even work, but it is ILLEGAL. Do NOT do it. Schneider is commonly Square D by the way (just like Eaton is Cutler Hammer). A QO breaker won't even fit in your Siemens panel. The HOM breakers might fit, but again, are illegal to use.

First make sure the fan control has enough capacity to handle the power consumed by both fans. Otherwise the wiring is fine either way. As BP points out, though, you will not wire them in in parallel, not in series. Except for switchloops (where white wires are to be reidentified anyway), you always connect white to white, black to black. Explicit series connnections are almost never used in household electrical wiring.