The Importance of HVAC Draft Gauge Measurement

[pat]

What about HVAC guys that remove furnaces off 5” flues and install power vents? How does that 30k btu water heater draft without the furnace helping during cold days when that big flue, that was originally figured to work together? Just wondering.

[akaredcrossbow]

A good draft doesn’t mean that your chimney is good! I’ve seen a 95% blocked chimney getting an over average -.03 -.04 draft on the gas hot water heater and a -.06 draft on the oil furnace. This is very common! Always get a chimney sweep out annually no matter if you have gas or oil heating your house, this is something your oil tech or plumber doesn’t do with an annual cleaning for the appliance. You can also have a free and clear chimney, but the inside could be deteriorated and the flue tiles lining the inside of the chimney can collapse and create a blockage. Most of the older chimney’s could also be unlined, meaning that there isn’t much protection between you and the harmful gases, especially if you have an interior chimney that is deteriorating on the inside. Have all flue passageways inspected or swept every year by a chimney sweep.

[dougg]

Stop touching the flue pipe in your videos. It is normally very hot if the water heater is on. So the causal watcher might think it's ok.