A good draft is vital for a good combustion.
Chimney draft test.
Induced draft heating systems shall be checked for spillage at the base of the chimney liner or flue.
The chimney creates the draft not the appliance.
Diagnose correct chimney draft performance problems with this simple draft test.
What this means is that when other exhausting devices are running such as a bathroom exhaust fan and there are no open windows the water heater should still vent properly.
It is possible to measure fireplace chimney draft by making a suitable test opening into the chimney flue not a usual practice and not something i recommend.
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When a chimney is shared by multiple appliances the appliance with the smallest btu input rating shall be tested first and remaining appliances tested in order of increasing input rate.
The chimney diameter should never be less than the diameter on the appliance flue outlet.
Chimney too short draft is proportional to the square root of the height of the chimney assuming that other factors don t interfere.
A tall chimney gives more draft.
We consider a normally good draft to be between 10 20 pa 1 2 mm vc.
How to improve the draft on a metal chimney when a chimney for a fireplace or wood stove is functioning normally a hot fire creates an updraft that sweeps waste gases from the fire up through it.
Measuring by waiving an instrument at the fireplace opening or chimney top is in my opinion a waste of time inaccurate misleading not useful.
There are lots of confusing technical explanations of how chimneys work and how a simple draft problem can result in some very uncomfortable issues.
Setting up the test.
Learn how to perform a smoke test with the help of this guide from chimney specialist barney dorman.
As a rule you should test the vent draft under worst case conditions.
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