Enlarging Chimney Opening for Water Heater

[avc8130]

Installing a new water heater. Upgrading from a 30 gallon to 50 gallon. Town inspector says greater than 35,000 BTUs requires 4" flue. I currently have a 3" and the new WH is 40,000 BTU.

What is the easiest way to open up the chimney hole to allow a 4"?

Air chisel?
ac

 

[dipper]

4" core bore bit would do it just fine.

 

[avc8130]

Do you have a link?
ac

 

[Hlidskjalf]

Go power vented!

 

[avc8130]

Go power vented!

Not buying a new water heater. This is fixing an install job that was done on "emergency" basis.
ac

 

[Hlidskjalf]

Well how long is the chimney? I have no idea how you're gonna ream out an entire length of the chimney. You need to fit 4" b-vent, correct?

I don't know about your local codes, but b-vent is mandatory here.

Might still be cheaper to get a power vented water heater, they're pretty inexpensive.

 

[avc8130]

The inspector said the 3" galvanized flue going through the cinder block with terracotta liner needed to be 4" galvanized.
ac