On Monday, September 9, 2013 2:53:26 PM UTC-4, jamesgang wrote:
On Monday, September 9, 2013 2:27:23 PM UTC-4, wrote:

On Mon, 09 Sep 2013 07:35:12 -0400, Stormin Mormon



wrote:







When I used to help install furnaces. If we would put



in a PVC vent furnace, often we'd have to put in a



chimney liner for the water heater. Boss would



explain to me that there wasn't enough heat to keep



the chimney warm. The flue liner would be expanding



aluminum tube that went to the top of the chimney.



I'm not sure what the formula for that is.







YEs, and there is a difference between interior and exterior walls.



Some time back, we switched our boiler from oil to gas, they said our



chimney was fine because it was on the interior of the house. Had it



been on an exterior wall, it would have required a liner.



I've seen some of this discussion about removing the furnace before. But what I don't get is why doesn't it matter in the summer? Furnace never runs then.


The issue is condensation. In the winter, the chimney without
a furnace, gets cold. The gases from the water heater can
condense and the condensate is acidic. Over time, it can
eat away at the mortar, causing the chimney to fail. That's
also why it matter if the chimney is outside the heated
structure or inside.