Since it is cold here right now and heating is my focus, here is my current set-up. First up is my Delonghi oil filled heater. It has two power setting switches. The MIN switch is 600 watts. The MED switch is 900 watts. Turn them on together is 1500 watts of course. I never turn them on together even though I power that heater direct from a 110 plugin at my power box. I have run a heavy cord from the box over to the coach and inside the door jamb. I am more comfortable taking some of the load away from the coach wiring although I have never had a problem. I modified a metal lip on the door jamb to allow the cord easier access. Look closely and you will see where I ground out a divot in the metal door lip. This stops the cord from pinching as well as it still lets the door seal pretty well.
Next up is my old faithful. It is a $40.00 Mainstays heater from Walmart. It has two settings. 400 watts or 800 watts. When I use one of these in the back hallway I only set it to 400 watts. It wont run at 800 watts from the rear coach circuit. It will just shut off. In warmer temps I have it run through a programmable temperature monitoring controller so it will shut off when not needed. In cold temperatures like I'm dealing with right now it is plugged in direct and will run 24/7.
Here is the current duct setup for the heat battery wood-fired heat. Intake is through the blue-lit computer fan mouth on the floor. In normal temperatures I stoke the fire only once a day at night but in cold temperatures like now I will also stoke it in the morning before I leave for work. I'm going to guess that its output is the equivalent to another 1000 watt heater.(Edit--The amount of heat produced from the heat battery varies depending on how hot I have stoked it of course. Upon reflection I think that 1000 watt figure is very low. That would be if the fire has smoldered down and the overall heat from the heat battery is moderate. When the heat battery is working at full temperature properly stoked I think it is probably the equivalent of at least a 1500 watt heater. Maybe even 2000 watts. It pumps out a lot of heat.) Yes, I have a messy kitchen table. Those little bottles are different flavors of "juice" for my electronic cigarettes. No, I guess my coach and I won't be featured in Better Homes and Gardens, haha.
Lastly I have the built in heating system of the coach which is an AquaHot diesel boiler system. Liquid heating throughout the coach with individual fans at multiple heat exchangers including one in the water bay. Five different heat zones with a thermostat for each zone. It also is how my water is heated. It runs off the coach main diesel tank. That tank holds 200 gallons of diesel and I always keep it topped up. The AquaHot is pretty efficient really but it is a complicated system and I don't want to use it too extensively so that I lessen the risk of an expensive break-down. This coach has some expensive-to-fix systems and the AquaHot is in that category. My hallway heat exchanger failed some time ago and I have bought a replacement but I haven't gotten around to installing it yet.
I also bought new batteries for the coach this year. It takes two 4D size 12 volt deep cycle batteries. BIG batteries. And expensive. I bought the Lifeline brand of AGM batteries. I bought them on-line from a dealer out of Los Angeles at a very good price. 550.00 U.S. dollars each and free shipping up to Eureka Montana. Considering they weigh about 130 lbs each (I think) the free shipping was a big deal. I picked them up in Eureka and brought them across the border without incurring any taxes or duties at all even though I was over my limit.
What happens if the power fails:
I have my power inverter switched off. Therefore, if the power fails the electric oil-filled heater and the Mainstays small electric heater stop working. The AquaHot and the heat battery will still provide heat at that point. The AquaHot will kick in when the temperature drops and the heat battery will still provide plenty of heat through convection up the ducting even though the intake fan will stop. The fans on the AquaHot heat exchangers will slowly draw the batteries down but those are very good batteries.I have an auto-start module for the coach's big diesel generator wired in to the 12 volt system. That module monitors the coach battery voltage. I have it set so that if the battery voltages drop to less than 12 volts the big generator will fire up and run for three hours. This will restart the electric heaters, recharge the batteries, and everything will run as normal even though the outside power supply is down. After three hours the diesel generator will shut down and battery monitoring will continue. The generator will start again if needed. I have tested that auto-start module and it started my generator at -15C. The module can be programmed to prime the diesel generator engine sufficiently for a good cold start plus I have synthetic oil in the diesel generator engine. It is A Kubota four cylinder diesel and a 10KW Onan generator.