View Full Version : shall chimney liner be resized after removing mid-efficient furnace?
10-19-2005, 12:42 PM
I am planing to change the 18 years old mid-efficient gas furnace to high efficient one.
Now the old furnace and water heater share the 5'' chimney. After changing to high efficient one, only water heater will use the 5'' chimney. I have following opinions about resizing the chimney liner.
1. It should be rezied to 4'' one, and quote is 200-300$
2. 4'' won't fit in 5'' one.
3. 5'' can be kept.
My house is a two-story. Water heater input is 44,000 btu and old mid-efficient input is 75,000 btu.
Thanks for your suggestions.
10-19-2005, 01:52 PM
Have you contractor review venting tables and see if it is permissable to still use the 5 inch chimney for the natural draft water heater.
10-19-2005, 01:56 PM
Actually, one contrator looked up some table and told me it's not necessary to change.
Two contractors directly told me to change it and charged it.
Two other contractors didn't even mention that.
That's why I am so confusing.
10-19-2005, 07:20 PM
I looked at TABLE 11.2 OF nfpa 54, American National Gas Code, not sure what is enforced where you are and I do not see why you could not use that 5 inch liner for just a drafthood water heater.
A 4 inch liner would be plenty big and you are saying the other liner is at least 18 years old. I would say the amount of money you have been quoted for a new liner would be worth the peace of mind.
10-19-2005, 07:45 PM
Looks like its 3 to 2 in favor of leaving it alone. The gama tables state that for a natural draft class 1 appliance, there is no minimum appliance input rating for drafthood equipped appliances. your 5" liner is well within the max.
10-19-2005, 07:55 PM
Thanks Carnak and Chill.
I am in Ottawa, Canada.
Really appreciate your help.
10-19-2005, 07:59 PM
Ontario Gas Utilization Code will be similar to NFPA 54, I am from NW Ontario originally, usually gas company would inspect and rule on vent size. Is it a rental water heater or your own?
10-19-2005, 08:04 PM
It's rented frm Direct Energy and was changed last winter.
10-19-2005, 08:33 PM
So the gas comapny will probably inspect, they should allow the 5 inch liner especially if it is in good shape.
When you fill in your profile and say where you are, you tend to get more help here. A big rule is not to ask about pricing.
Carnak; Things have changed since you left Ontario. Gas inspections are no longer required, Only in new housing now. It is now the responncibility of the gas tech to ensure the job is done up to code..We are audited by a provincial inspector every 2 years.
10-20-2005, 05:09 PM
Just my two loonies worth:
After 18 years that liner is due for relacement.
They are acid resistant not acid proof.
Meaning by now for peace of mind you should change it.
I think a four inch will suffice. Micigan and Candadian codes are almost Identical. We take from the IMC to which our great nortern neighbor (Southern if you cross the Border at Detroit. Funny how that works) contributes heavily.
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