Join Date: May 2012
Location: North Vancouver, BC
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Forced air heater duct design
I was down at the boat last night checking on it, (hanging out in the man-cave!) And was having an closer look at the heater installation. I discovered that Jeanneau for some reason, had installed the heater so that it draws all of it's intake air from outside, rather than from the cabin space. This is may be fine if you are just taking a bit of the chill off a late season evening, but when the weather is below freezing as it was last night, it is far from efficient.
I like the idea of drawing 100% fresh air in some situations, but for winter operation I would like to have the option of recirculating the air, so my plan is to install a wye in the return duct with a damper that allows me to switch between the 2 branches. One branch will be fresh air and the other will be return air, hopefully with the option of a mixture of both.
The challenge is, where to draw return air from. The simplest thing would be to install a grille in the aft bulkhead at the back of the aft cabin, but that is not ideal because it will likely increase noise levels in that berth. Also, with the cabin door closed it will not be able to draw air from the rest of the boat. Ideally I would like a return duct that draws from the main salon, but I am not sure there is a route I can run a 90mm duct.
I am curious what kind of duct layout other boats have for their heaters. Is this idea of drawing 100% outside air instead of return air a common thing, or was Jeanneau just taking the easiest way?
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2011 Jeanneau 39i Azura