Hydronic system questions
I'm trying to get a layout going for my bus conversion. I've got two roof top A/C's. I may replace with a heat pump in the future when they wear out. For the time being, I have to figure out the heat and hot water situation. The bus has a 45k btu proheat engine heater. After reading threads and fb groups til I'm dizzy, I think I may have a a decent layout plan. To keep it as simple as possible, I'm thinking about installing a 20 gallon marine water heater in the rear engine bay with the proheat. I have valves going to the engine now. I can tie into that and have an engine coolant loop going through the marine heater. The normal domestic water side would have boiler antifreeze. I would have one pump that went to a manifold and have valves that go to 2-3 hydronic sections through the bus. On that loop I would also have a plate heat exchanger to heat the DHW. I'm thinking when running down the road the engine will keep the 20 gallon water heater up to temp. When parked the 120v heater element will be used. If it can't keep up, the proheat will be turned on. When we need hot water, turn the circulation pump on, and we're good to go. Anybody see any problem with this layout? I'm thinking the 20 gallons should hold enough heat to be able to get a shower without having to use the diesel heater. Also need to find a way to control the proheat to turn on when the tank gets cold for when we're using the heat.