I've been considering ducting for my HPWH because it's in a somewhat inappropriate space... so I wonder what you & others here might think of this wacko idea.
It's in a tiny little utility closet in the centre of my main floor that barely fits it and the air handler for the ducted heat pump we replaced our furnace with. I was left feeling like the sales guy wasn't interested in selling us the right system for our application. (Proper air volume, proximity of noise to living area.)
To deal with the tiny room getting very cold and probably operating inefficiently, I removed a piece of sheet metal that was screwed over a hole that duct cleaners punched in the air return for the heat pump (top right in the photo). Its fan runs at a low speed continuously, so the cool air from the water heater mixes into the air in the whole house. Seems ok. The house is comfortable. What I don't like is that the gap under the utility closet doors now functions as an air return.
I was wondering how crazy it'd be to connect the HPWH to that air return duct on both intake and outlet.
Now that I'm actually writing that out, I can think of a some possible negatives:
- If I just connect both ends to the air return duct, it'll create a loop (say if the air heat pump is off)
- If I split that loop, then air will be continuously moving through the HPWH and its filter will become a pre-filter for the air heat pump. The pipe diameter would be smaller, too, so it couldn't be a full split.
- There may not even be enough clearance by the outlet -- there's just 4.5" between it and the air handler.
Now I partly wonder if I should add an intake vent above the doors like Evan, with the cool air just making its way out under the doors... but what I don't like about that is the thought of dumping cool air onto any area of our concrete floor in cooler months. The semi-adjacent kitchen is bad enough already. I also don't like the idea of the visuals of a vent like that in our family room. :-\