Return vent above wood stove

[Terry Beck]

Return vent for a forced air furnace in ceiling of finished basement, I'd guess 9' ceiling without pulling out a tape measure. A wood stove just underneath the return vent. The home buyer had a heating expert in addition to me doing the home inspection. So, why didn't the licensed HVAC contractor mention this as a concern to the buyer? Am I missing something? (sorry about the quality of the picture)

He seemed pretty sharp, though young (these days, everyone seems young to me). He was also kind enough to describe how some home inspectors don't know what they are talking about.

I also got on a ladder and pulled the return vent cover off to make sure that the wood stove exhaust vent wasn't passing through the return air chase (it is not, there is blocking between the I-joists that separates the return air chase).

[Garry Sorrells]

On the practical side the return is circulating the warmed from the stove through the house.
Were there a High Wall Return and Low Wall Return located on the upper floors?

So, your concerns are ____ ??

[Rick Cantrell]

SECTION M1602
RETURN AIR
M1602.1 Return air. Return air shall be taken from inside the
dwelling. Dilution of return air with outdoor air shall be
permitted.
M1602.2 Prohibited sources. Outdoor and return air for a
forced-air heating or cooling system shall not be taken from the
following locations:
3. Rooms or spaces containing solid-fuel burning
appliances, provided that return-air inlets are
located not less than 10 feet (3048 mm) from
the firebox of such appliances.

[Garry Sorrells]

Rick,
OP 9ft ceiling would make vent about 10 ft from stove wouldn't it???

[Rick Cantrell]

3. Rooms or spaces containing solid-fuel burning
appliances, provided that return-air inlets are
located not less than 10 feet (3048 mm) from
the firebox of such appliances.
30" high fire box, 9' ceilings,
Nope, closer than 10'

[Garry Sorrells]

30" high fire box, 9' ceilings,
Nope, closer than 10'


Guestimated angle of the wangle...to vent

Not knowing exactly how high the ceiling except maybe 9 ft

[Ashley Eldridge]

On the practical side the return is circulating the warmed from the stove through the house.
Were there a High Wall Return and Low Wall Return located on the upper floors?

So, your concerns are ____ ??

My primary concern would be that the air handler could pull enough air into the return that the appliance would have a difficult time acquiring sufficient combustion air. When natural draft goes up against mechanical it will lose every time.

Ashley Eldridge
CSIA Director of Education28779
Chimney Safety Institute of America (CSIA) | Plainfield, IN (http://www.csia.org)

[Jim Warters]

If the appliance had a difficult time obtaining sufficient air to to operate, room occupants would undoubtedly experience the problem first.

As a former fire inspector, I would interpret the 10' requirement to be horizontal, not vertical or at an angle. I believe the intention is to reduce the possibility of recirculation of any combustion products escaping the appliance.

[BillKace]

Return vent for a forced air furnace in ceiling of finished basement, I'd guess 9' ceiling without pulling out a tape measure. A wood stove just underneath the return vent. The home buyer had a heating expert in addition to me doing the home inspection. So, why didn't the licensed HVAC contractor mention this as a concern to the buyer? Am I missing something? (sorry about the quality of the picture)

He seemed pretty sharp, though young (these days, everyone seems young to me). He was also kind enough to describe how some home inspectors don't know what they are talking about.

I also got on a ladder and pulled the return vent cover off to make sure that the wood stove exhaust vent wasn't passing through the return air chase (it is not, there is blocking between the I-joists that separates the return air chase).

I don't see it as a concern. It is no different then having a return anywhere else in the room as far as having a draft issue with the wood stove. Also I assume the room has supply registers from the air handler also. This would offset any return that was being drawn from the room when the unit is running.

Bill Kace
Nationally Certified Air Balance Technician

[Billy Stephens]

My primary concern would be that the air handler could pull enough air into the return that the appliance would have a difficult time acquiring sufficient combustion air. When natural draft goes up against mechanical it will lose every time.

Ashley Eldridge
CSIA Director of Education28779
Chimney Safety Institute of America (CSIA) | Plainfield, IN (http://www.csia.org)

Ashley,

Wouldn't the return vent be drawing ( warmer ) air from the top of the room with combustion air ( cooler ) for the Solid Fuel Appliance being replaced and drawn into the bottom

[Raymond Wand]

Is there a fresh air inlet from exterior (outside) into the firebox? If so the appliance is not drawing air for combustion from the interior.

[John Kogel]

Terry is saying the return air vent may be less than 10 feet from the firebox, and if so it does not comply with the rule. Correct.

Apparently, the HVAC guy did not see this as a problem, and many folks here agree. Certainly when the furnace is running, it would be blowing warm air into the room, but maybe not if the floor vents are closed off.
Where did the 10 foot rule originate? Is that measured from the interior edge of the firebox or from the combustion air vent? What if it's 9'11"? :confused:

If it is less than 10 feet, it doesn't meet the minimum requirement. I would measure that from the nearest point of combustion air supply for the woodstove, which would likely be below the door. I can't quite reach it from here. :biggrin:

[Jerry Peck]

If it is less than 10 feet, it doesn't meet the minimum requirement. I would measure that from the nearest point of combustion air supply for the woodstove, which would likely be below the door. I can't quite reach it from here. :biggrin:

I just measured it, the distance is 8 feet 9 and 13/16 inches ... :thumb:

[Raymond Wand]

This is a Canadian publication

See page 23 the left diagram

http://www.cleanairplan.ca/documents/woodguide.pdf

[Bob Harper]

I would caution you on this practice. If you have an EPA certified woodstove, it should be able to handle up to -15Pa of depressurization. However, an old clunker leaky POS non-EPA stove can leak at equilibrium. At the very least, this would probably cause smoke odors throughout the house.

IF you're hell bent on doing this, at the very least install low level unlisted CO monitors outside the sleeping rooms and on every floor level.

The quoted code applies only to spaces where that room serves as the source source of return air. Still, returns near fireplaces and woodstoves can be problematic. This is why open returns near draft hood equipped waters heaters are so dangerous.

[Rod Butler]

. . . .

IF you're hell bent on doing this, at the very least install low level unlisted CO monitors outside the sleeping rooms and on every floor level.

. . . ..

I love the logic in your post. :D

I was not aware of a code requirement for the ten foot restriction. Interesting. Had I been asked for an opinion I would have said "looks good to me." But like I have said before I am not a home inspector.