Musings about Integrated Chiller + Diesel Heat on Power Cat

[codingparadox]

We have a 48 foot power cat that currently has a very poorly-designed HVAC system consisting of three separate all-in-one heat pump units in the skylounge that have miles of ducting to the rest of the boat. Thermostats and air intakes are in stupid places, making it very hard to hold temperature anywhere on the boat, much less where we specifically care about it. And they use a ton of power to try to do so. They're also all older and rusting, and the coolant lines to them are cracking, so we're nearing the point of a pretty massive service to get everything back in safe order. As such, I'm heavily leaning toward just starting over.

We're currently looping and working full time, but we plan to take this boat to the northwest as soon as mobile Starlink is available and do seasons in Alaska/Desolation/Vancouver Island/etc., and possibly take this boat to Europe after a few years of the northwest. So strong heating will be a must in the new system. To this end, I've been excited about the idea of doing a fully integrated chiller and diesel heat system, especially since it gives us hot water for a lot less power than being electric-based like we are now.

However, when I look around, literally the only company I can find doing one of these systems are Webasto. The system looked pretty good -- pick up a V50, a 50kBTU diesel heater, run coolant lines around the boat, and stick air handlers where I want them. I engaged the Webasto folks when we were on Lake Michigan this fall, and they came out and measured everything, and actually suggested /not/ doing the integrated system, instead running two fully parallel systems (one diesel heat, one heat pump chiller). This seems like both incredibly expensive as well as a missed opportunity for an integrated system (not to mention where the heck am I gonna put a full second set of air handlers in each room...)

Given the split-system advice from the Webasto folks themselves, I'm torn on how to proceed. I'm still tempted to avoid their advice and go with a single integrated system. Any advice at this point from people who have (or have not) done an integrated system like this?

[wefleenor]

David and Hannah,

I had my 48ft custom power catamaran built in the PNW, launched in 2010, and only this summer came down the coast to SF Bay. I initially installed a 50K BTU ITR hydronic heating system that was great at heating, but did find a need for air conditioning more often that I thought. Before coming down the coast, I replaced the hydronic heating with 4 Velair units which are variable speed reverse cycle systems. My boat guru talked me out of installing any type of chilled water cooling system. Even in my boat which was designed to be maintenance accessible, he felt it would be impossible to properly wrap all the piping needed to prevent it from sweating and causing issues. In your manufactured boat, which is likely designed to make use of all available space, it would even be more difficult to wrap the pipes.

Bill