David, when we camp we use the diesel burner system in the evening/night as it's our heat for the coach as well. During the day, we use the electric side for dishwashing, etc. The electric heating element cannot keep boiler antifreeze hot enough during the night. So if you do that, you will keep fresh fuel in the unit all the time. I figure I use about a gallon a day to a day and a-half doing it this way depending on how cold it is outside at night. We usually camp along the Washington, Oregon or California coast or up in the mountains so it can and does get cool enough to have the AH come on a few times in the evening/nighttime.
Some owners have taken it upon themselves to add pipe insulation to the coolant lines where accessible to help make the system more efficient. Taking sharp bends out of the duck work hose also will make the unit run more efficient. I believe if you search for Hydro Hot issues on the forum you will see the pictures members have displayed. It’s something I want to do, but not easy since the coach is stored in one place and we live another.
Monty & Janet - 2007 Alpine APEX 40 MDTS
S/N - 75715 - Retired - Master Certified RV Tech