Direct Vent Clearance

**Andrew Kolar** · 06-26-2009, 03:46 AM

I am having a little trouble deciphering exactly what the manufacturer meant by some of the clearance specifications in the diagrams.... It shows 18" of clearance needed under a deck, porch, veranda, etc. But this isn't under the deck, just next to a privacy fence (low maintenance composition product). What are your guys’ thoughts in regards to acceptable clearances?

http://i303.photobucket.com/albums/n...A090625004.jpg

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**John Arnold** · 06-26-2009, 04:22 AM

What's on the other side of the fence? Neighbor?

**Andrew Kolar** · 06-26-2009, 05:11 AM

This is a zero lot type condo, but there is nothing directly on the other side... (no neighboring deck, windows, doors, etc.). The privacy fence is just to block the view to the nieghboring deck / porch which is a good 30 + ft away.

My question is more in regards to if acceptable clearance appear to have been met to the privacy fence itself. Best I can tell by the diagrams, they have. But this type of situation doesn't appeare to be directly addressed.

**Jerry Peck** · 06-26-2009, 06:05 AM

Looks like that would, typically (and may vary depending on the manufacturer's installation instructions), ... typically be 6" to non-vinyl sidewalls and 12" to vinyl sidewalls.

That fence is a sidewall and thus the right edge of the termination (the round termination, not the plate) would need to be at least 6" from the fence on the right, and it is not.

Now here is a question: Is that fence on the 'property line' between the two condos?

If they were not condos but 'separate structures', that might make a difference.

However, being condos in one structure that may not make a difference.

**Andrew Kolar** · 06-26-2009, 07:40 AM

I believe it was about 5" from the edge of the round termination to the privacy fence. The privacy fence is not on the so called center or property line of the condo building (between the units)... Jerry, could you elaborate on how that may or may not make a difference?

I understand now that it probably doesn't meet the manufacturer's specified 6" of clearance... and those are the guidlines that really need to be followed. BUT I am curious, has any one ever seen where this type of situation has actually led to a problem ??

**Jerry Peck** · 06-26-2009, 08:00 AM

Originally Posted by Andrew Kolar

I believe it was about 5" from the edge of the round termination to the privacy fence.

I find it hard to believe there is 5" between the vent termination and the fence. See photo and annotations.

The privacy fence is not on the so called center or property line of the condo building (between the units)... Jerry, could you elaborate on how that may or may not make a difference?

That becomes a mechanical exhaust and I would have to look up the code on exhaust locations and clearance to property lines, but I think it is 10 feet.

**Andrew Kolar** · 06-26-2009, 08:32 AM

Your right (probably 1" or less) when measured on a horizontal plane like that (and probably the correct way to do it). Is that where the measurment is to be taken, from the edge of the base diameter? When I said 5", i was talking about from the closest point of the vent termination to any edge of the composition privacy fence. See picture below.

http://i303.photobucket.com/albums/n...directvent.jpg

**Jerry Peck** · 06-26-2009, 10:24 AM

Yes, measure horizontally out from the termination, not from the plate, and in the termination shown that would be from the diameter of the termination, actually the cap diameter which was a little larger but would have made it harder to show what I was trying to show.

Heat rises, so the clearance to the wall (fence) is horizontal along the wall the termination is through to the adjoining wall (fence).

**brian schmitt** · 06-26-2009, 02:18 PM

andrew,
it is essential to have the installation instructions for the appliance. i have seen many that require an 18" sidewall clearance for the flue. need air circulation around the intake/exhaust pipe was the reason given.

**Bob Harper** · 06-26-2009, 04:14 PM

2009 IRC definition of "mechanical Draft System: A venting system designed to remove flue or vent gases by mechanical means, that consist of an induced draft portion under non-positive static pressure or a forced draft portion under positive static pressure.

Direct Vent Appliance. A fuel-burning appliance with a sealed combustion chamber system that draws all air for combustion from the outside atmosphere and discharges all flue gases to the outside atmosphere.

I believe you will find this is your typical direct vent termination. Without the listed instructions, we can all speculate til the cows come home but those instructions hold the answer you seek.

JP is correct about where to measure from on the termination. This fence would be considered a "sidewall" or "corner" in the vent termination diagrams.

If the other side of this fence belongs to someone else, then it crosses the property line, which would probably violate local zoning regs. even if it passed the code and listing. Functionally, this is a mess and would be highly susceptible to performance problems, not to mention looks retarded (technical term). I would be concerned about the long term effects of heat on a thermoplastic fence in proximity regardless of whether it met the listing or not. Also, plastic is a soot magnet. Also, you must have clear access to inspect and service this termination and I would say this is an impediment.

Andrew, can you provide make and model?
Bob