Gas furnace return air

[Tim C. Howell]

what is the minimum distance a return air pipe can be from the front of the older style furnaces? My notes tell me 10 '. Plus, where do I find the HVAC codes
Thank you,

[David A. Andersen]

you are correct, 10 feet.

IRC/UMC building code.

[Brian A. MacNeish]

Originally Posted by thowell

what is the minimum distance a return air pipe can be from the front of the older style furnaces? My notes tell me 10 '. Plus, where do I find the HVAC codes
Thank you,

In a very loose building, a return in the area of a naturally vented furnace may be OK but I don't believe in the 10 foot rule. It doesn't really tell you what's actually happening with pressures in the furnace area.

The best approach to this situation is to do measuements of negative house pressures when the furnace fan and a larger exhaust device such as the dryer or range hood/downdraft is operating. If the area near the draft hood goes strongly negative, there may be a chance of backdrafting.

[David A. Andersen]

and what are all the home inspectors out there without a micro-manometer going to do if they don't have the equipment to do a flu draft pressure test?

I think it is appropriate to simply document the measurements and go upon your merry way when they're closer than 10 feet.