Flexable aluminum flue liner

fredster

Hey All!
I want to install flexible aluminum flue liner in my chimney (there is no flue liner in this chimney). I am venting a Gas furnace ( 82% efficiency) and a 40 gal. gas water heater. My questions are: what diameter venting pipe do i need to vent both of these appliances? I am going to use flexible vent pipe, do i need to use stainless steel or am i ok with aluminum? and last but not least, do i need to insulate this venting pipe ( the majority of it will be traveling interior within the house until it get above the roof line, with a approx 6 ft above the roof line.

beenthere

Moved to HVAC forum.

beenthere

Liner size depends on the size(BTU input) of the appliances connected to it, the lateral length and the height it is/will be.

scottmcd9999

In addition to beenthere's comments: Stainless is required in my area, but may not be in yours. Check with your local code office (but be prepared to have them balk at you venting a fossil fuel appliance - often that must be done by licensed contractors).

No, you don't insulate it. The goal is to remove waste gases from the living space, not to retain heat.

ben's plumbing

how many total btus will you have...size of furnace and water heater...alot in my area are 5"....but again need to know your sizes..

fredster

My gas boiler btu/hr is 140,000. My 40 gal gas water heater is 38,000 btu/hr. making it a combined total of 178,000 btu/hr. The vertical ht of the chimney is 30'. The current vent is 6"...do you think that would be a sufficient diameter venting flue size?

ben's plumbing

yes 6" should handle about 238,000 btu you do have to figure out run from appliance to chimney and if its single wall connector... but I think you should be fine...