Horiz Venting and Outside Air: Manual vs. Reality

[kelvin]

I have been following this forum for a few weeks without posting and want to thank you all for all the useful info and great tips. Now that oil is cheap again, I'm ready to install the pellet stove I've been waiting for since July so I can start burning my $299 pellets. Whatta financial genius.

So here's what I'm struggling over now: After reading through many threads on venting, it seems like there's sort of a consensus that straight out venting is a bad idea (at least without a standby power supply) because of smoke blowing back into the house in case of loss of power. And after scanning many threads on outside air, it seems like plenty of experienced installers say outside air is unnecessary.

However, my installation manual places the opposite emphasis on each. It strongly (in bold) recommends installing an OAK. Yet it presents horizontal exhaust as a perfectly acceptable venting option, with only a soft advisory about installing some vertical pipe to create natural draft.

I know two people who have had pellet stoves for years who vent straight out with no problem, even upon losing power.

The main question: Has anyone here actually experienced their house filling with smoke because of this?

I was planning my install with a straight out vent and an OAK, but am now second guessing both of those choices...

 

[smaxell1]

I have been following this forum for a few weeks without posting and want to thank you all for all the useful info and great tips. Now that oil is cheap again, I'm ready to install the pellet stove I've been waiting for since July so I can start burning my $299 pellets. Whatta financial genius.

So here's what I'm struggling over now: After reading through many threads on venting, it seems like there's sort of a consensus that straight out venting is a bad idea (at least without a standby power supply) because of smoke blowing back into the house in case of loss of power. And after scanning many threads on outside air, it seems like plenty of experienced installers say outside air is unnecessary.

However, my installation manual places the opposite emphasis on each. It strongly (in bold) recommends installing an OAK. Yet it presents horizontal exhaust as a perfectly acceptable venting option, with only a soft advisory about installing some vertical pipe to create natural draft.

I know two people who have had pellet stoves for years who vent straight out with no problem, even upon losing power.

The main question: Has anyone here actually experienced their house filling with smoke because of this?

I was planning my install with a straight out vent and an OAK, but am now second guessing both of those choices...

The outside air kit has nothing to do with the smoke coming back into the house in the event of a power failure. Outside air is recommended because a lot of stoves would be new installs, and more likely to be in a well insulated, well sealed house. An old, drafty house is not going to have much of a problem (except for air infiltration in areas where there may not otherwise be). If you take a properly sealed house, and start venting air from the inside to the outside, you are competing with other appliances (dryers, etc) that also vent inside air to the outside. At this point, you could have negative air pressure in the house compared to the outside. It can a) limit the amount of air available for the stove, and b) draw air in at odd spots that may cause problems. I have worked in restaurants for years. All of the equipment in the kitchen has huge fans venting the smoke and hot air outside. You have to have an air return (powered in that situation) or you get negative air pressure in the building.

As far as the outside vertical rise on venting, the draft will occur in a warm chimney. It tends to draw the air out of the stove. If the pipe is cold (ie a recent startup on the stove), there will be no draft. If you vented into an interior chimney, even with it lined with pellet pipe, it would still be warm enough to pull air up the chimney. If you go straight out of the wall, there is nothing to draw smoke out period. The only time smoke will vent is with positive air pressure in the stove. Some stoves will leak more smoke than others without this. I doubt it would FILL the house in any situation. You will smell it, but I would expect no worse than messing with a wood stove. Any reputable retailer that I talked to told me that I should vent up three feet. It may have been to get an extra $70-100 sales in pellet pipe, but why not do that and make sure you have a nice, reliable install? If you invested this much in a stove, and pellets - you may as well do it right. In addition, you buy yourself a huge distance to ground flammable material. Not much chance of errant sparks out of the stove - which DO come out - starting a leaf fire next to your house.

Anyway... OAK - preferred, but not required - except in a really tight building.
3' vertical rise - PREFERRED, but not required... but STILL PREFERRED.

Assess your need for the OAK, but definitely do the three feet outside.

Just my $0.02 worth

 

[Jester]

You also tend to see more soot around the caps on a 100% horizontal install on the outside of the house. Its nothing dangerous, just looks crappy when it happens, and that probably isnt 100% of the time either.

 

[dman]

I was wondering about the vertical venting too. Last night when I was messing with the power my battery back-up didn't keep the stove going long enough & smoke filled (eggagerated) the room. I would like to run vertical venting up to the roof if I can avoide getting smoke in the house especially since my wife has asthma.

Currently, I have the stove in the daylight basement with 4" venting straight out. I would like to vent it vertical up past the roof (20 to 25 feet). Am I correct in assuming the smoke will draft up when the power goes out? This would allow me to sleep with the bedroom window open at night without getting smoke in the room during regular stove use plus there would be no soot on the side of the house & if the power goes out I wouldn't get smoke in the house.

I just want to make sure of this before I inverst in that costly pipe.

Thanks

I just have two tons of pellets in the garage. I'm not a pellet hog!
Avalon Arbor free standing

 

[imacman]

.... Am I correct in assuming the smoke will draft up when the power goes out? This would allow me to sleep with the bedroom window open at night without getting smoke in the room during regular stove use plus there would be no soot on the side of the house & if the power goes out I wouldn't get smoke in the house......

That's the advantage of having at least some vertical run...the natural draft from the hot gases will help pull the smoke/fumes out if the stove stops suddenly. 20-25 ft is a lot...do you have to go that far?

 

[dman]

Yes I would have to go about that high. I have a daylight basement which is where the sove is. The pipe would have to go past the 2nd floor, between two windows & thru the roof eave. 1st floor=8 ft + 9 ft for 2nd floor + eave portion 1 ft + 2 to 3 ft above the roof = 20+ ft

 

[smaxell1]

Yes I would have to go about that high. I have a daylight basement which is where the sove is. The pipe would have to go past the 2nd floor, between two windows & thru the roof eave. 1st floor=8 ft + 9 ft for 2nd floor + eave portion 1 ft + 2 to 3 ft above the roof = 20+ ft

If all you are concerned about is the stove venting naturally in the even of a power outage, you really don't need to go that high. I would vent out, up, 5-10 feet max and terminate 16 inches from the wall. An exterior chimney that tall with the relatively low temperatures coming from a pellet stove will eventually cool the exhaust gasses within the chimney. Then you will have NO draft at all. I assume this is why you are limited to around 33 feet MAX.
You also MAY pay a price in reduced efficiency of the stove. At least you are already using 4" pipe, since you need that if you go past somewhere around 15 feet or something like that. You also need to be THREE feet above the roof, and two feet higher than any point within 10 feet. Just another fyi in case - you also should not have more than 180 degrees of joints within the pipe installation (ie two 45 degree and one 90 degree, or two 90's).

---scott

 

[dman]

Thanks---I checked out the prices & it would be cost a bundle---at least $400.00. I suppose I could just go up a couple ft from where it comes out of the wall. Would that work?

 

[smaxell1]

Thanks---I checked out the prices & it would be cost a bundle---at least $400.00. I suppose I could just go up a couple ft from where it comes out of the wall. Would that work?

I am surprised you were able to find it that cheap!

Are you talking about going straight out the wall, then 90 degrees up? Since you said you were in a daylight basement, I assume you can do this. Otherwise, if you are going up the inside wall of the basement, and out through the sill or something, then up the outside wall - you would be using three 90 degree bends. (I don't believe the elbow for your termination counts. )

Otherwise, out the wall (with thimble), 90 degree cleanout tee, up three feet, elbow, terminate at least 12 inches from the wall.

Easier and cheaper - probably do it for around $150 or so.

---scott

 

[kelvin]

thanks for the replies

 

[muss]

Been burning straight out 18" from my log sided home for a total of 4 months. No problemo . Saved a chunk of $$$ . Muss

 

[smaxell1]

Been burning straight out 18" from my log sided home for a total of 4 months. No problemo . Saved a chunk of $$$ . Muss

You are lucky then... most of the straight out venting I have seen leads to soot on the outside of the house, and smoke in the house when the power goes out.

---scott

 

[krooser]

My dealer...Earth Sense Energy Systems in Dale, WI... recommended the horizontal vent with outside air. They have done hundreds of these installs in the nearly 20 years they've been in biz with virtually no problems.

I did the install myself. I paid them $50.00 for their inspector to come out and check my work... no problems. He checked for any carbon monoxide leaks and checked my vent install carefully.

I'd do the horizontal install again in a minute... no reason not to.

With all due rsspect to my pellethead compadries but many folks live in the NE where, it seems, many people have been scared to do anything that some over-zealous building codes inforcement officer might find not to his liking. I'm kinda from the old school where you pretty much know what you can and cannot do based on your knowledge and research on a given subject.

I did tons of reserach on pellet stoves and installs and pulled the trigger so to speak... of course I do (or did) most everything around here myself. I installed my own gas-fired tube heater in my shop, remodeled my house myself (including plumbing and electric) , disassembled my pole building shop and moved it 40 miles to my place and reassembled it on my own lot. Stuff many folks wouldn't be comfortable doing but I did basically because I could... and am too cheap (or broke) to pay anyone to do something I can do myself.