Insulated flue??

Robert O'Connor_7

Be careful to read the manufacturers installation instructions carefully. If the maximum is 25 feet of developed length for your apliance, my question is ,what, and how many extra feet did you add for those elbows?? In most cases they will either give you a chart/table or refer you to local codes. adding just two 90 degree turns could put you over the maximum. I'd check....Robert O'Connor/NJ

Dave Faust

Insulated flue ??

I am installing a propane fired "Takagi" instantaneous water heater. It requires a class three flue which will leave the appliance & run straight vertically for 19 feet. I don't anticipate any condensation problems (the manufactures length limit is 25 feet). The flue will run from the basement, through an closet chase on the first floor, then through an unheated attic, out the roof. The flue nominal diameter is 3 inches. As there is no condensate drain I was considering puting 12 inch fiberglass pipeinsulation around the flue as in passes through the attic and maby the chase. This could have a 1 or 2 inch wall thickness while maintaining 4-1/2" of clearance between the flue and the insulation. Any thoughts as to wheather or not this would be a valid idea or just foolish overkill?

Also: Where should I install the manufactures suguested/required (for cold climate instalations)gravity operated check valve damper?

Thanks All

Jack_23

Vents

First the disclaimer, I represent Rinnai, a manuf of on demand water heaters. I also have a great deal of venting experience having installed a lot of systems and represented a couple vent pipe manuf.

I believe you will have trouble running a "near max" length vent though an unheated space. These are efficient appliances. As such you have a low stack temp exiting the appliance whcih when run thru unheated space is a problem. Your insulating the pipe "may" work. What if it doesn't? In all of my venting seminars I always emphasize that the manuf specs should never be exceeded and if there are questions, the manuf must answer them satisfactorily. You have support. Don't be creative on venting. You assume the liability.

I also recommend that appliances be located, if possible, in a location to minimize vent length. Reduced cost and typically better operation.