I use a combination of cold frame and greenhouse now. I started out with cold frames which were basicly a frame covered with heavy guage plastic. I can tell you that it can be 2 degrees below zero and be 80 in the greenhouse if the sun is shining and I'll have my vents open. I have 2 mini-max thermometers in my greenhouse. It doesn't matter what the temperature is outside. It will vary according to how much sunshine you have. I can tell you though that even on a cloudy day the sun can heat a small space very fast and very hot. The best way is to put a thermometer in a box open on one side and facing north and put it in there. The thermometer will be shaded from direct sun and give you a true reading of the temperature in there. I am not a big fan of those upright shelves with cover. The cover does not come right to and lay on the ground so cold air goes up them at night and they are very tippy. My son bought one and after oit blew over for the third time he ditched it. I suggest you put it in a protected place if you have wind at all or somehow secure it so it doesn't blow over. My cold frame is a pop-up cold frame that sits low to the ground and I leave my plants in it at night as long as the temperature is close to freezing or above. But then I get the benefit of the ground heated in the day giving off heat at night.

There is a large write-up on the Black Max earlier, you will gain much insight. As for the B&S, read all the write-ups at Amazon, Home Depot. I have read that B&S has a weak valve problem, and when repairs are needed, the service centers keep them for months.

Sounds like the compressor failed. either electrical problem or the unit itself is bad. Open it up, and see if can find something wrong, like burning fuse, burning smell, etc.. other then that, not much you can do. portable AC is all sealed, it is not designed to be fixed by customer or even AC tech.

That's quite a mix of questions you've asked and a lot of them, I'm afraid, can be answered with: "That depends." When you Google the sites about sizing generators, most of them encourage you to add up the wattage of everything you want to run and then use that as your minimum capacity. Except in a narrow band of cases, that's nonsense, of course. You've noted that not everything is on at the same time and it's unlikely that every motor--sump pumps, refrigerator, furnace fan, etc.--will start up at the same instant. Accounting for "diversity"--the probability of different mixes of things being used simultaneously--is a basic when planning capacity. Otherwise, if most people added up the size of every light bulb and electrical device in their house, they'd run out and double or triple their service. The biggest single draw you've listed is the washing machine, which you've designated as "optional", or subject to discretionary management (e.g., maybe don't run it when the sump pumps are working hard and everything else is on). They highest demands would occur when a motor starts up (sometimes requiring 3 or 4 times the rated wattage of the motor), but that is usually covered by the surge capacity of the generator, unless a large motor is being powered. Here, you're probably talking about motors in the range of 1/3 or possibly 1/2 h.p. A 6KW genset ought to be able to handle it. If you want a seat-of-the-pants guestimate, you would probably do just fine with a 5-6KW generator (that's continuous capacity--surge would be a bit higher). I could be convinced that more power is needed if those are exceptionally large sump pumps and are pumping frequently. What concerns me more is the method for connecting the generator to the house power system. The right way to do this (and I'm sure your electrician will confirm this) is to use a transfer switch to isolate utility and generator power. This issue of how you connect the generator to the transfer switch is something you should discuss with the electrician. A 20-25' cord is feasible, yes, if it is a very heavy duty 240V generator cord, made for purpose. I'll skip the question about brand because I don't think it's a proper in a forum of this type to indulge in product endorsements. (That's only my take and others may disagree.) From the specs you've given, I can't see any reason you'd need DC power or an inverter. (The generator already has an inverter built in.) Any good quality generator has a governor that responds to load and consumes less fuel when there is less demand for electricity. A generator under full load will make more noise and use a great deal more fuel under full load. As far as keeping the generator battery charged, there are a couple of approaches. If you are dilligent in starting up and testing your system regularly (some recommend montly), that should keep the battery charged. Another approach, if circumstances permit, is attach the battery to a small, inexpensive solar panel (say, 3 watts) with alligator clips. This isn't enough to charge the battery when if it runs down, but is enough to provide a "float charge" and, at that capacity, it shouldn't require a charge controller. It's about a $30-40 solution.