I do love my wallas, and like Tom and some others, I need a little work done on mine now to get it back to 100%. If I did not have it...I would take the time to peak at the Dickenson heaters. They have one about the size of a shoe box that is real neat and you can watch the fire too. Advantages and disadvantages with just about any system you pick. Basically on my wallas, the little "spring washer nut" that holds the fan in the "toliet paper sized tube" to supply the air/vent movement slipped down, and shut down my heater. I do like the fact that when things are not 100% on the wallas, it does shut down. Karl told me to push the fan blades assembly back up to "where I thought it was right...but not to far up as to block the air...and super glue it." I did. It works great on high down to about mid-range, but choaks down a bit on low....so, I just burn her a little warmer and open the windows a little more for temp control. Now, I really need to just take her out and send her back to Karl...but, when do I really want my boat to be without it...?
As for starting the wallas....I simply keep in mind it is diesel in design, and like all diesel engines....they need to warm up good before you go using them and putting loads on them...and for me, this includes the fan that comes on when you lower the top. I just leave my top up for about 5 minutes and run the unit on high...then lower the top and the temp if needed.