Starting to poke around the internet for water heater stuff and found this:
This fits the bill for the two coil water tank, one loop with the engine coolant being circulated and the other fed by an Espar or other hydronic heater. This also has a 12V electric element which I've also seen controllers use as surplus solar loads if the batteries reach full charge and there's still sun shining on them. A unit like this is appealing.
Still thinking about how it (the Espar) might be plumbed to be able to pre-heat the motor if desired, but that should be possible. It would likely require a handful of valves to divert flows but shouldn't be too complicated. I would prefer to keep them separated as to not put too much of an additional load on the engine's coolant pump and I want to make sure there's a sufficient bypass that the Espar's pump isn't going to burn out pushing against a closed thermostat. It's all been done before so I am certain it's possible, but I want to make sure I'm not introducing extraneous issues.
SureCal 30 liter / 7.92 gal Vertical Twin Coil Calorifier
SureCal 30 litre / 7.92 gal Vertical Twin Coil Calorifier
www.heatso.com
This fits the bill for the two coil water tank, one loop with the engine coolant being circulated and the other fed by an Espar or other hydronic heater. This also has a 12V electric element which I've also seen controllers use as surplus solar loads if the batteries reach full charge and there's still sun shining on them. A unit like this is appealing.
Still thinking about how it (the Espar) might be plumbed to be able to pre-heat the motor if desired, but that should be possible. It would likely require a handful of valves to divert flows but shouldn't be too complicated. I would prefer to keep them separated as to not put too much of an additional load on the engine's coolant pump and I want to make sure there's a sufficient bypass that the Espar's pump isn't going to burn out pushing against a closed thermostat. It's all been done before so I am certain it's possible, but I want to make sure I'm not introducing extraneous issues.