Rethinking a liner

Cyclist77

I will be installing a Weil-McClain CGa boiler this summer. Actually it was just delivered! The chimney is 40 years old. I am wondering how necessary it is to install a stainless steel liner as this boiler has a 84% efficiency. The chimney is in the center of the house.

Advice would be great!

jesmed1

We have a 100-year-old center chimney serving two 86% WGO-5 oil boilers plus a gas DHW heater, with no problems. The chimney has a terra cotta liner and was inspected two years ago by a good local chimney sweep. He said it was in good condition.

We would have needed a new stainless liner if we had converted our boilers from oil to gas, but we ended up sticking with oil, so the chimney is fine as is.

However, your CGa is a gas boiler, so you may need a liner. Our local building inspector would have required a liner if we had converted to gas, even with a non-condensing burner, and even though our terra cotta liner is still good.

delcrossv

What's it's condition? Liners aren't a necessity with non-condensing boilers- IF the terracotta is not decayed.

EBEBRATT-Ed

Liners on an exterior chimney are required on gas with almost any boiler if you are in a cold climate.

Interior chimneys are supposed to be ok if in good shape and properly sized.

Bob Harper

First, the OP should read through the archives here. Tons on liners.

Still seeing a lot of misinformation on chimneys and liners. Urban legends and mis-reading codes.

Can someone please post pics of a single masonry chimney and flue that meets NFPA 211? Anyone? I'll wait.

As for the WM Gold boiler, you need a ss liner regardless of the condition of the chimney for: containing the byproducts of combustion, keeping the acidic flue gas condensate from attacking the alkaline mortar converting it into sand and salt so those soluble salts can migrate to attract water and hasten the death of the masonry, size the flue for a quick start, to stabilize the draft, and to allow the appliance to come closer to its stated efficiency (it never will).

NFPA 211 Standard Development

You can read it here for free.