Thread: Return air placement

What do you guys think of this installation? There is a return air duct in front of the fireplaces wood stove insert.
What would you write in your report, if anything?

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Aside from the clearance to the fireplace as we've previously discussed here, it is a fire hazard. Most stoves require a 16-18" area of non-combustible ember protection in front of the fuel loading door. In addition, most stoves have a requirement for thermal floor protection as well. However, raised hearth extensions are generally not accounted for in those stated requirements so consult with the mfr. for each specific model's listed requirements.

If a hot ember popped out of that stove, it could easily fall into the return where the flames would be fanned as hot sparks were blown right into the filter, where a brisk fire could ensure.

Does that stove have a full length listed liner?

HTH,
Bob

[quote][Aside from the clearance to the fireplace as we've previously discussed here/QUOTE]

Here's the applicable code cite off of the 2006 IRC: M1602 The house was built 30 years ago, so I really don't know whether this was allowed back then. Not that it matters, I will write it up from a common sense standpoint.

One of these days I'll take the FIRE training.

Does that stove have a full length listed liner?

I doubt it-- if one thing is wrong, there's usually more.....

A full length liner is still not required is it? I am under the impression that they can still just run up to the first flue tile, assuming that there is a tile (will be on this one). There's no way for me to determine whether this has been done without taking things apart, which I will not do. I always recommend a level 2 inspection, not that anyone ever actually does this inspection.

I'm just pre- inspecting off of the MLS pictures.

Here's the other stove insert. I'm wondering if I'll find singe marks on the carpeting.

Can you install an insert with a direct connect to the first flue tile in lieu of a full length liner?

It depends:

If the chimney passed a Level II inspection
meets the sizing criteria in the codes
if the stove mfr. allows it
if the local jurisdiction allows it
if the direct connect is sealed off so room air cannot communicate with the flue gases.

99% of all chimneys will fail the Level II
If you install with just a direct connect, sweeping requires pulling the stove, sweeping the 5' liner, sweeping the flue then reinstalling the whole mess, which btw makes the sweep the new installer of record. The cost of such a sweeping done properly should be several times that of a 'normal' sweep job alone. That means few homeowners will pay this much to get the proper service at least annually.

A full length liner allows a quick and easy sweeping without pulling the stove so it gets done on schedule more often and does not require special tools such as a stove puller and can be done in 1/3 the time. The liner takes care of most issues with the flue but the chimney itself must still be essentially intact enough to hold the liner.

You can peek down the flue from the top to verify the presence or absence of a liner. Often when there is a liner, it is uninsulated, which means it still is not listed.

Thank You

M1602.2 Prohibited sources.
Outside or 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.

When it comes to wood stoves, some insurance companies may ask the buyer of the house if the stove is UL listed. It's nothing that really affects us as HIs but I do let buyers know there is a possibility it may be asked when they try to get insurance.

Nick, it's better to have a listed stove than an unlisted stove for sure but.......... UL 1482 came out in 1980. The first EPA Phase emissions regulations didn't come out until years later so while being 'listed', which btw can be done by any accredited lab such as OMNI, ETL (Warnock-Hersey), UL, etc. the listing is to the std. The IRC does require stoves to be listed but it does not address the emissions rating or AFUE.

Also, some insurance companies REQUIRE an inspection of a stove prior to writing the policy. There may be one or two insurance companies around that offer discounts for inspections. For years, chimney sweeps accepted a $15.00 discount to the homeowner from Farm Home just for the referrals.

We are currently in EPA Phase II and beginning to explore how much lower technologically we can push emissions even lower (not much). Currently 4.1 gm/hr for catalytic stoves and 7.5gm/hr for non-cats.

Just a reminder, there are many current production wood and pellet stoves that qualify under the federal tax credit up to 30% or $1,500 if anyone is interested.

How to spot these early stoves? Well, you need to find the rating plate. If you can locate it, there will be an absence of clearance diagrams on the old stoves. It will state the listing on the tag. If it is EPA Phase I or II certfied, that info. will be on the tag. Generally, AFUE ratings will not be on there.

In all cases, your best move would be to recommend a Level II by a qualified tech./ inspector and locate the listed instructions. I would include a recommendation not to use it until such inspection and given the ok to use.


Good discussion,
Bob

Repair, Safety Issue: Poor location of return air duct in front of fireplace, recommend relocating, may compromise fireplace combustion resulting in CO emission into the home.

It Looks like the grill has for some time been their. Are you sure it is not an outside air duct for the stove it's self? Don't get confused with a fresh air supply for your heating or ac system, they are not the same. Recommend a good smoke detector be installed in the room and hall way to the bedrooms. In a wood burning appliance the smoke will kill you before the CO level gets to that point in a wood stove

Some rather interesting observations there Cobra. Have you ever seen a makeup air kit with a floor grille like that? To be a combustion air kit, it would have to be attached to the stove itself and off hand, I don't know of any inserts with an air kit option.

A smoke alarm in that room will get plenty of work as every time someone opens the door, it will probably spill enough smoke to trip the alarm.

So what is it in the smoke other than carbon monoxide that you say will kill you before the CO?
Thx in advance,
Hearthman

Bob, I think Cobra was referring to the 'lack of O2' in a smoked up room.

As Cobra has said, it may be, and liekly is, the fresh air make-up for the fireplace and not a return to the furnace.

Or it could be some genius figured putting the return in front of the fireplace would capture heat and recirculate it. The OP would have to tell us if he tested it to see if it was indeed a return for the HVAC or 'something else'.

Brandon?

Acid in the tree sap. If you ever walked into a room full of smoke from a wood stove, you would immediately start to choke and cough, you would want to get out as soon as possible. The smoke would dissipate the oxygen in the air and mixed with the chemicals in the wood would burn your lungs, eyes and nostrils. Sure there is a minute amount of CO but that mostly is caused by chemicals in the wood. But
If you ever walked into a room full of CO and sit down or parked your car in the garage, sat in the front seat, started to read a book, and started the engine, you would simply fall asleep and die. Carbon monoxide is a colorless, odorless gas which is tasteless and non-irritant. It is somewhat less dense than air and, although it is a product of imperfect combustion, it is inflammable
CO is produced when carbon (including coal and coke) or carbon-containing fuel (including petroleum hydrocarbons; e.g., gasoline, fuel oil) does not burn completely to carbon dioxide, because of insufficient oxygen. CO is present in the exhaust gases of internal combustion engines and furnaces. It is toxic because it binds to hemoglobin in blood much more strongly than does oxygen and thus interferes with transport of oxygen from lungs to tissues.

Wow! Where to start?

There are over two dozen various compounds formed in woodsmoke. Some may or maynot be present. Also, many of these compounds change into other stuff depending upon temps and conditions and thus their concentrations fluctuate, too.

If a woodstove is properly vented and burned, the smoke goes up the chimney---not into the room. I don't know of anyone who would stand around in a room full of woodsmoke at a higher concentration greater than enough to smell it. Yes, it is irritating, which means usually self regulating. If you smoke out the room, you exit long before anyone gets sick. Sorry but there is just no statistical data to support your claim that woodsmoke rather than CO kills but there is plenty of data that proves CO kills before fire.

Now, CO is produced by incomplete combustion--not by chemicals in the wood. You must have sufficient time, temperature and turbulence along with plenty of oxygen to make carbon dioxide rather than CO. Just understand incomplete combustion of wood does make a lot of CO.

Your description of the effects of CO is correct.

Your best protection is to have combustion appliances installed by techs holding the proper qualifications then have it inspected by an inspector holding the proper qualifications and finally, get yourself low level unlisted CO monitors.

I thought I was clear that you would not stay in a room full of smoke if you could get out , if you did not the smoke inhalation would kill you. You are told to get low because smoke rises, But in a room with just .01% of CO which is enough to kill you, you would not even know you were about to die? I certainty never implied that smoke killed more than CO, If I did I am sorry. It would be interesting to see a comparison. Cobra

Or it could be some genius figured putting the return in front of the fireplace would capture heat and recirculate it. The OP would have to tell us if he tested it to see if it was indeed a return for the HVAC or 'something else'.

Brandon?
__________________

In my defense, I was pre- inspecting off of the MLS listing--- I will no longer do so. Things have been a little crazy for me in the last week. I just had a baby 8 days ago, so I was trying to save a little time on- site so I could get back home and help out.

Having said that:

Originally Posted by Brandon Whitmore

I just had a baby 8 days ago,

OUCH! I bet that hurt a lot!



Congratulations for your wife and you having a new baby.

Congratulations for your wife and you having a new baby.

Thanks, and I'll choose my words more carefully while on this forum

Here's 4 of my favorites and I suspect they may amuse Bob?

Jerry, aren't those cold air returns (ducted into the furnaces) in photos 2 and 4???

CARs all Robert and their locations are more common than dirt.

There's nothing necessarily wrong with those returns (in photos 2 and 4) right? I see many CAR's centrally located in smaller homes. I do realize that they do not provide the comfort level of multiple returns, but is there something I'm missing to call them out???

Robert - think "backdrafting."
2009 IRC M1602 & UMC 2000 906.2