View Full Version : Duct work
09-29-2005, 11:31 AM
Hi there,my name is Mike and I'm in commercial.We are about to put a furnice in a house that my friend bought.40 years old.Any tips on running the duct work?
09-29-2005, 11:58 AM
There are too many things ton list here.
Here is a little info:
First, contact your electric power company, or some other entity in your area, and find out if they conduct manual J heat-gain audits and if they can recommend things to do to reduce your home's energy usage.
"Only after you have reduced your home's energy heat-gain and heat-loss should you consider installing new equipment that has to be accurately manual J sized to the new lower heat-gain heat-loss conditions."
Air Conditioning Efficiency Recommendations Summary List:
* Wherever possible reduce the cooling load of the house. Overhangs above east and west windows are particularly effective in reducing cooling load.
* Perform Manual J for all installations and select equipment by using Manual S.
* Insure that the system installed never exceeds the capacity of the equipment suggested by Manual J or N for commercial buildings and Manual S for selecting equipment sizing.
* Size duct systems based on Manual D. (If in doubt size upwards.)
* Determine the grille location and characteristics using Manual T.
* Confirm proper evacuation of the line set and indoor coil with a micron gauge.
* Confirm proper charge using the manufacturers' suggested method.
* Confirm proper airflow by test. The flow can be determined from the coil pressure drop when pressure/flow data is available from the equipment manufacturer or can be determined with a duct test rig or flow hood.
* Increase the duct insulation to R-6 (at least on long runs in the attic).
* Confirm that the duct leakage is less than 3% of coil airflow for a new system and less than 6% of coil airflow for an existing system.
Do the ductwork installation right, or don't do it!
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