Heater Duct Insulation

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The runs are so short i doubt you will get much heat loss from the ducts. I actually have to open a window because it can get a bit too hot.
 
I understand the duct as it comes out of the unit is quite hot according to a brief conversation I had with Wabasto. Was told to keep vinyl hoses and wiring well away from it. Did not specify the distance from the furnace before the danger was not present. I was thinking of exhaust wrap for about two feet, mainly to preclude wiring and hoses from dangling and touching the hot duct. I am installing the unit under the sink as per Mike's suggestion. Wires from my overhead are rather helter skelter, so I am being extra cautious. I won't have much space behind the stove since that is also where the high pressure pump and 42" membrane for the water maker is located, so I am error ing on the safe side.
 
I never considered the fact that one would want to insulate the ducting to prevent heat damage to surrounding areas through which the duct runs.
 
I'm interested in insulation for both reasons. I've only got about five or six feet of ducting but it is all inside cabinets. I tested the surface temperature of the duct and it is over 200 F. So temperature inside the cabinets is pretty high and limits their use to durable goods. Secondly, even though the surface area is limited I only have a Webasto 2000 rather than the 3900. So I need all of the heat I can get out of it. Fiberglass exhaust insulation will likely suffice to protect anything that may contact the duct. Insulating for efficiency is another matter.

If no one chimes in with an existing solution, I'll report back with what I come up with.
 
For anyone in the PNW are who is interested, Sure Marine stocks high temp foam insulation in appropriate diameters for the various heater ducting supplied in 6ft. sticks. They also verified that a little over 200F duct temperature near the heater is normal. I've only got five or six feet of duct so I'm measuring that on the outlet end. I will be doing the insulation both for piece of mind around wiring and cabinet contents as well as to extract max BTUs out of my little heater. Now I just have to keep the dog from laying by the vent and singeing her hair...
 
I installed a Wallas heater last winter which has two separate outputs. One of my outlet runs is fairly long but I intend to insulate all of the ducts as soon as I get around to it because of the heat losss - especially in the longest run back to the dayhead in the R-31 midberth. The Wallas distributor sells foam insulation to put on the aluminum ducts they sell. The Wallas ducts are larger (typically) than the wabasto ones.
 
Just an update for anyone interested. I ordered one 6ft stick of the insulation from Sure Marine. The ducting I'm using is a little less than 2 1/2 in. and the ID of the insulation is 2 7/8. It is about 3/4 in. thick. So in straight runs you can just slide it on. The extra space doesn't hurt. On bends, etc. it's easier to cut out a strip to it fits the duct tightly. I just used plastic wire ties to fasten it in place.

Performance wise, with the duct running about 200 degrees F, the outside of the insulation is just warm to the touch. The cabinet where the heater is located is warm inside. Without the insulation it was too hot to put any kind of food in it. Now it will be a nice dry place for storage or tortilla chips and saltines. The second cabinet that ducting runs through is barely warmer than inside the cabin. Bottom line is that now nearly all of the heat is making it into the cabin where it belongs and the cabinets are useful for storing anything desired.

Mission accomplished.
 
sounds great. I need bigger diameter but i will definitely do that before next winter.
 
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