# Safe temps for 0" clearance?



## pcampbell (Jan 22, 2009)

I have a DV wall furnace that is listed as 0" clearance to combustibles.  I measured the pipe temps today with my infrared gun and found the hottest temps to be around 240F.  I am just wondering what is considered the maximum safe range for clearance to framing wood, drywall, etc.


----------



## R&D Guy (Jan 22, 2009)

Zero clearance is likely just for the unit, not the pipe.  Pipe almost always has clearance required.  The install manual should specify this.   If its 240° F and touches wood/combustibles then I'm sure its too hot.  If it's 240° and there is an air gap then you need to measure the surface temp of the surrounding combustibles.  

ANSI Z21.88a-2007 is the standard fireplaces are certified to today, your furnace is likely a variation of that standard, but Z21.88 says any combustible surface not exposed to the room (not seen e.g. inside the wall) has a maximum temperature limit of 90° F above ambient temperature.  So if your house is 70° inside, the combustible cannot exceed 160°.  That temperature measurement is taken when the system is at equilibrium (hottest).

If you are concerned then I don't think there is any reason you can't add extra clearance.  I've been guilty of that before.


----------

