Insulating a dry stack exhaust

Hello, I would like to see if anyone would have some advice on insulating a dry stack exhaust. Everything is in place but all the insulation (ceramic tile with fiber board) was damaged and removed. How much room between the wall and the muffler is recommended? I'll attach some pictures. Thanks

I guess Asbestos is no longer in vogue?

Not sure what is in vogue, but I have looked at some blanket type insulation but I don't really know how close and what type of material I can build around the blanket. I'm doing some research but I was hoping someone might be able to help with some real word advice.

Wrap with fiberglass tape, then wrap again with thin layer of aluminum or SS shiny sheet metal. The FG provides insulation, the shiny wrap limits radiative heat transfer.

Looks like the pipe below the muffler is still wrapped in its lagging / blanket. You want the same thing for the entire muffler and section of pipe inside the house. Once you're thru the overhead and outside, the pipe can stay bare.

Leave a couple inches, if possible, around the blanket and line the trunk area with something non-combustible, and you should be OK.

Do some Googling. There are a number of specialist suppliers around the country that can help with this. Obviously concentrated near workboat centers like Seattle, Gulf, etc.

Like most things, the Devil will be in the details, too. Brackets & hangers will transfer heat and need attention paid to them. Check the condition of any flexible sections, and make sure you have enough of them. Best bet is to have a commercial guy familiar with these systems look it over for you. Fires suck.

The right way to do this is to have a new lagging blanket made. These are typically sewn by companies that specialize in marine exhaust. This will thermally insulate the muffler from the trunk, be removable for service, and last a long time.

The trunk should also be insulated, both thermally as secondary protection and acoustically for noise reduction.

The three most popular incombustibles for this are mineral wool (rock wool), fiberglass and ceramic.

Mineral wool should be available from any industrial insulation supplier because its common in restaurant and commercial use. It's available as a blanket or semi-rigid board. The appropriate fiberglass should be available through marine outlets, ask to browse a catalog or go online. Ceramic is the latest and greatest and expensive.

As an acoustic barrier that's incombustible lead would be the best choice, in either a 1 or 2lb sq ft sheet.

With insulation, more is better.

Contact DeAngelo exhaust.

DeAngelo Marine Exhaust Systems | Diesel Soot Filtration

Commercial Fishing Supplies | Seattle Marine & Fishing Supply Co.

Browse, then call... They are helpful folks.

According to Dave Gerr's book "Boat Mechanical Systems Handbook" (anyone doing this kind of work should have this book) ideally the exhaust trunk should have (quote, page 153, second paragraph)"about 30% or more of the cross-section area inside the trunk (after adding insulation) open for airflow". Seriously, get the book. While its fun to kick things around here on the most interesting of forums, things like this need a real naval architechs knowledge.

You could use ceramic fiber insulation (not asbestos). It is available in cylinders, boards and blankets. I would buy two nesting cylinders, cut them in half vertically and put them around the muffler with the joints staggered. They can go in contact with the muffler or leave a small gap (say 1/4") with spacers on the inside of the cylinders to maintain the gap.

Take a look here:

Custom Exhaust Jackets | Marine Insulation

I used this - Lloyd's Registry approved, easy to use. Quiet.

ExoWrap® Insulation System

"ExoWrap® Insulation System
product-icon1ExoWrap
Insulation System

Lloyds
ExoWrap®, the ‘one-step’ insulation system, is the quick and easy way to insulate high temperature surfaces in vessel engine rooms.
ExoWrap® is a revolutionary system made from biosoluble vitreous silicate fibre which is reinforced with an outer jacket of heat sealed aluminum foil. In tape or blanket format, ExoWrap® is applied in one step eliminating the need for bulky and time consuming layered insulation.
ExoWrap® can be easily removed and reinstalled by using the ExoWrap® Silhesive Tape and is rated for use to 1,000 C max. ExoWrap® can be used throughout the engine room.


IMPA Code Width Thickness Length Roll/Box
81 38 71 50 mm (2″) 3 mm (1/8″) 7.7 m (25′) 24
81 38 72 100 mm (4″) 12 mm (1/2″) 3.3 m (10′) 6
81 38 73 300 mm (12″) 25 mm (1″) 7.7 m (25′) 2
81 38 74 600 mm (24″) 25 mm (1″) 7.7 m (25′) 1

For use on bent and flanged pipes in areas where maintenance is not a consideration and/or space is limited. ExoWrap® has a pressure sensitive adhesive on the inner side for ease of installation.ExoWrap®Tape"

Sorry it didn't all copy. A single kit of sufficient wrap to do that system was about $300. In fact, I have a 4' long muffler and the amount to do my system was more than sufficient, I gave some to a friend to do one of his risers. You should buy an extra roll of tape, the amount that came with the kit wasn't quite enough to do all of mine. I used lots. I also used the 12" width as it was easier to wrap different shapes.

Custom blankets are big money and look great but you are hiding yours anyway.