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Ask Gaztech Your Own Question
Gaztech, HVAC Technician
Category: HVAC
Satisfied Customers: 465
Experience:  Owner at Gaztech
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I have three rooms, all r13 insulated walls, r30 insulated

Customer Question

I have three rooms, all r13 insulated walls, r30 insulated ceiling with 1/2 inch drywall used across the whole room. The four rooms are 16 ft x 11 ft with a 9 ft ceiling, 15 ft x 21 ft with a 9 ft ceiling, 18 ft x 13 ft with a 7 foot ceiling, and a 21 ft x 18 ft with a 12 foot ceiling. The 16x11 room has one single pane wood frame window with one exterior wall, the 15x21 room is completely interior, the 18x13 room has 2 exterior walls with 3 single pane wood windows, and the 21x18 room has two exterior walls with a total of 5 single pane wood frame windows.
I'm wondering what size furnace I should be using and what size pipe I should be running into the walls. The joists are 14.5 inches apart at 3.5 inches deep across the entire house as it was built in 1878. The farthest run for the furnace would be 40 feet. I plan on running two cold air returns per room using thermopan. Since the walls are so thin I was unsure what the real size of the duct work I should be using to heat the room or if I will have to use two ducts to make up for the small space?
Submitted: 8 months ago.
Category: HVAC
Expert:  Gaztech replied 8 months ago.

You cant use exterior walls for duct, Should you not get a HVAC contractor to assess the design ??

Customer: replied 8 months ago.
I was going to use the interior walls for running duct work. The building is actually much larger then these several rooms with a size of almost 9000 sq ft, however, the HVAC contractor told me to section it off into usable zones to save from using above 120,000 btu furnaces and crossing into the industrial sector. These rooms were the first set of rooms in the new zone. We do not have a contractor locally that will assess layouts without putting the furnaces in at the same time. The contractor I am working with instructed me to hook up the lines inside the wall and he would finish the runs, etc.
Customer: replied 8 months ago.
House is located in Iowa if that helps at all