Chimney Liner

DS88

HI all. I am in desparate need of help. I am being taking around in circles so i just want some valuable and trusthworthy opinioin.

I had a contractor install a 6" SS chimney liner when I replaced my gas boiler. Installed a Burnham IN4 model. The flue or vent or exhaust pipe is around 4-5" (definitely not 6).

Now I need masonry repair work for the crown of my chimney and the contractor said that the 6" SS liner is not the correct one because it is not matching the exhaust vent from my boiler in the basement. He claims this is causing too much condensation which is the root cause of my chimney deteriorating.  He wants to install a new liner to match the size of the venting in the boiler.

A call to the original liner installation company said this 6" liner is fine and nothing else needs to be done.

My question is what should be the proper lining size?



Thanks

icesailor

Liner size:

Its my understanding that the diameter of the liner is decided by the actual input of the appliance that is venting into it. Just because a boiler (like say a Weil-McLain WGO-3 oil boiler has a 7" exhaust doesn't mean that the liner has to be 7". Because the same boiler with 9 sections (WGO-9) uses the same rear section and needs a 7" vent.

The flue size is more dependent on how long the flue is and how many BTU's are going in to it.

Most chimney "Specialists" couldn't read a flue sizing chart of it was on a great big blackboard in Kindergarten.

I would question why the flue has fallen apart though. It may have been rotten in the first place. And condensation is the reason that you need the stainless steel liner.

He probably can't give you a understandable explanation of why flues need to be properly sized. About how the same flue that is too short will have the gasses going to fast and too long and they go too slow.

I would hope, but I'm not very hopeful.

ALIGA

find a new chimney guy

the purpose of the liner is to protect the brick/mortar from deteriorating. he has no idea what he is talking about.

ChrisJ

Liner size

Just a warning I'm only a homeowner.

I'm going to have to agree with icesailor on this one.  A few years back I had a lot of chimney problems and my understanding is the following.

A liner is installed for a few reasons.  One is to protect the chimney from condensation, another is to keep flue gasses from leaking into the home and yet another is to keep the gasses warm and to improve draft.

I believe a 6 inch liner is a common size and shouldn't cause a problem, however on smaller appliances a smaller liner could improve draft and reduce condensation as could using an insulated liner.  Length of the liner is just as important as the diameter as well as how many appliances are being vented into it.  When you vent multiple appliances the size has to be increased.  The manufacturer of the liner should have a chart showing what size appliances should be connected to it for whatever given length and for multiple appliances they will have another chart.

In the end you should always go by what the manufacturer of the liner recommends and they always go by input btus as icesailor said.



Like I said, I'm only a homeowner but this is my understanding. Personally, if you have adequate draft at the appliance with the 6 inch and it is installed properly I would leave it alone.

DS88

Thanks everyone.

All, i appreciate the responses. I will leave the liner alone and enlist more contractors for the chimney draft. You guys just save me a ton of time and hopefully money.



thanks!