Like you, I have the combustion air just drawing from inside the cabin.
The condensation inside the cabin seemed worse this time, and I'm thinking that had to do with the high humidity outside.
You may be right about the high humidity outside but my thoughts are:
1. The colder it is outside, and the warmer you get the inside, you are creating a differential that is not separated by an insulated barrier, (our non-insulated C-Dory walls), and so you are going to get condensation. That is going to happen whether you are heating with inside or outside air going to the combustion chamber.
Does the heater really dry the air out? Or is it just heating the most air, which is going to condensate on the cold uninsulated hull?
2. See above #1. The heater, (depending on the type and fuel), can either dry the air out or produce more moisture (as in the case of burning propane especially in a closed area.)
Before installing my heater I read many forums. Various modes of thought, and I followed the one that said by taking the combustion air from inside the cabin, it would then draw outside air into the cabin thru our not so sealed boats, in turn ridding the damp air from inside. However, in retrospect, thinking about it and from the experience I'm having, if the outside air is real humid, you are probably bringing more moisture into the boat than what you are removing.
3. I would agree with you and the forums in thinking that using the air from inside the boat for combustion, you do draw in outside air through the “leaks”, but how much an how much detriment would be variable depending on ambient environmental temperatures and humidity. I still think that the combustion process is going to remove more moisture than what you are drawing in and the condensation problem is due to the differential of the surfaces, inside and out not being insulated.
I spoke with my brother on the way home, and he said the only way you are going to remove the moisture, (assuming the outside air is also humid) is with a dehumidifier. No room for this on our CD-22's!
4. You are both right there.
Our uninsulated hulls are going to be cold with very cold outside air temps and no sun shining (as in night time.) I suspect you live in a dryer climate, where the outside air being brought into the boat, displacing the moist breath air, provides a better atmosphere for leaving that combustion air intake inside the boat. But since most of my boating is in more humid air, and close to or below freezing temps at times, I'm probably going to be better off drawing combustion air from outside the boat and just dealing with the lower moisture content inside the boat by running fans to try and circulate as much warm air as possible. Colby
5. I don’t think my climate is all that much dryer here in Sequim, or when I am out on the water. I really rarely run my Wallas. I just dress warmer if I need to. I do have a fan that I run quite often, to move the air around when I am running the Wallas. I have had very little issues with condensation, but I did have some last summer. That was even when I was not using the Wallas, and it was over night in the birth. I think it was mostly due to not having the fore hatch open as much as usual due to the constant rain.
I might have, sort of, (REALY DID) go off on a rabbit trail here, so my apologies to Mike and should redirect folks back to the pictures from the St John’s CBGT. Sorry for the scurrying around, and Colby, maybe we should run this out under a new thread.
I just put “condensation AND heater AND combustion AND air” into the C-BRATS Search box and got about half dozen entries. Take a look at the responses and see which one seems to fit your likes better, and we could go on from there if you want.
Hope this can be helpful.
Harvey
SleepyC :moon
