chimney liner?????

[hungry]

Hello everyone and thank you in advance.

Here goes.
Do you need to install a chimney liner IF you are replacing an old unit with an 80%+ induced draft unit?

[Gunnery Sergeant Hartman]

yes

[beenthere]

Unless its a clay liner, or other approved liner in the chimney already. And the chimney isn't too big for the new smaller 80% furnace.

[hungry]

Thank you (beenthere) yes it does have clay liner, It did not make sense to run another liner down there.
Thank you

[bigtime]

you need a liner

[hungry]

I thought ( INDUCED DRAFT) took care of the slow moving gases( only mid-efficiency) going up before they condensate? or no?

[BaldLoonie]

If 1 or more sides is exposed, line it.
If furnace is alone and no WH, line it.

Inside chimney with water heater, gas code sez: the flow area of the chimney cannot be more than 7 times the outlet area of the smallest draft hood appliance.

Well, that would be your water heaters with likely a 3" (7 sq inch) outlet. So if the internal dimensions of your tile liner are more than 49 sq inches, code says line it.

Of course if you don't want to take any chances, line it. Liners are cheap, chimney repairs aren't!

[billva]

flue gasses are lower temps. with an 80 furnace as opposed to an older 65-70.

therefore condensation will occur at colder temps.

the flue gasses are acidic and will eat through any mortar joints in the clay liner.

new chimney= $$$$$

LINER=$$$

it's up to you i guess.

[billb7581]

Hmmm, my chimney has long since been orphaned to just WH duty but is on an inside wall, so I guess that's why it still drafts properly.

[hungry]

THANK YOU ALL

Direct vent it is then. lol

[beenthere]

Originally posted by billva
flue gasses are lower temps. with an 80 furnace as opposed to an older 65-70.

therefore condensation will occur at colder temps.

the flue gasses are acidic and will eat through any mortar joints in the clay liner.

There is no motar joint on clay liners.

Teracotta, yes there is.