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Interior door clearance...

1203 Views 4 Replies 5 Participants Last post by  joecaption
What gap is typical for adequate air flow? I need to trim down a few interior doors. The first two are 36" wide for 100sf or so bedrooms with no individual returns. The master has double doors measuring 60" total with a return in the room. There is one large return in the hall near the two bedrooms. I'm thinking 3/8" for the small bedrooms and 1/8" for the master. Please let me know if this works. I want the heat pump to work as efficiently as possible.
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its all in the math... first you have to know what the supplied air flow to the room is. Then you can calculate the needed exit area under the door (h x w).... but I think just about everyone here will agree that normally you would have to under cut the door by about 2 to 3 or more inches for the air flow math to work out correctly.

The alternatives are:

1. install return ductwork in each room.
2. Install transfer ducts (sometimes called jump ducts) from each room to open main areas (your hall way if I read correctly)
3. install a grill in each door, of the size needed for the airflow into the room.

From experiance on my home, transfer ducts made a huge difference!!!!! kids sleep with their doors closed and putting in the transfer ducts keeps the rooms at the same temp as the rest of the house and the hvac system is much more efficent, which has more then paid for the diy cost of the installation!!!! The ducts basically allow the air from the "sealed" off rooms to get back to the air handler. again, a huge difference in comfort and economy !!!!
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