While I currently don’t own an Ollie, I’ve visited the plant and sales office in September of this year. Hope to place an order 1/2020.
I’ve, like many, have done an exhaustive review and comparison of travel trailers, Motorhomes, etc., including their respective mechanical systems. Leave it to the Europeans to out-engineer the U.S. manufacturers (predominantly in Indiana where design and decor are STUCK in the ‘80’s) with sustainability and efficiency being their guiding design impetus. All that being said, to address your specific citing of the Alde heating system which uses glycol as the “medium” transferring heat via finned radiators pumped via plastic supply lines is a great system. However, since the Oliver is equipped with a propane gas ducted forced air heating system the logical conversion would be a Truma Combi System which is a propane gas tankless hot water heater and a gas ducked forced air heating system. Using the existing duct system would be the most efficient conversion rather than attempting to re-plumb supply lines and place finned radiators in the trailer hull.
I hope Oliver considers the Truma Combi System as an upgrade since the Truma Tankless Water Heater is already an option...
Just my thoughts and observations.