Hi Pete and Solarnewbee,
It does seem chaotic inside this unit. Wiring to 2 mainboards I guess. Also the input-outpur board usually attached to the control board is mounted on the front panel just behind the lcd screens instead. Lots of relatively long wire runs because of the layout.
My battery bank is (16) 200ah sla batteries, 4 sets of 4 for 48v. In spring, summer and fall I usually run the whole house on my inverter 24/7. Normally that's only 800-1000 watts with occasional well pump (1500w) and/or microwave (1100w) here and there. Plenty of solar now to keep the batteries up. When my wife decides to use the oven it kicks my total up to 4500w or so jumping to 6000w when the well pump also kicks in (for a short while). That's about the max it ever gets. I haven't tried running the electric dryer on it so don't know what it draws. She hangs clothes out in good weather by choice.
Anyway, improved heat transfer takes some time and work, but should extend the life and reliability of the unit.
Solarnewbee, if one board runs hotter than the other, to me that means the load isn't being shared equally. Not the best situation. I wonder if it wouldn't be better to just disconnect one mainboard, leaving the second as a built in spare. That way when it eventually blows up (they all do), a few minutes rewiring to the spare and a new lf driver board on the control board, and you are back online. The question is whether it will run with one mainboard or is something in the control board expecting both to be there? No idea. I will be watching temperature on both my mainboards to see if mine share load equally or not. Also of possible note,\; The ten lead ribbon from mainboard to control board is short for one mainboard and very long for the other. Wonder if that has something to do with poor load sharing? Maybe try a long ribbon in place of the shorter and see if the heat load is more balanced?
I'm probably going to change the transformer fan to a lower speed (more quiet) fan and control it separately from the other 2. Also there will be an added fan on top of the xfmr blowing down into the middle that runs continuously. The mainboard fans will probably be rewired in series making them run at half speed and much more quiet. Keeping the mainboards cool shouldn't be a problem with independent controls insuring the fans come on at the right temp. I've learned never to trust powerjack's fan controls. Usually they don't turn on fans until things are way hot.