Pipe Installation Question

[Simonkenton]

I am an old-time wood burner guy. I built a log home in Georgia in 1988 and installed a Vermont Castings Resolute in the living room. The pipe went up 8 feet, did a 90, went through the wall, did another 90 and went up above the roof.
This was a great wood stove! I wish I still had it. Of course this was prior to the big EPA changes in all the wood stoves. The total length of pipe was about 20 feet.
This stove was easy to light and just burned great.

In 1999 I installed a new Waterford stove at my new log cabin in the NC mountains. I did the install the same way, a 90 to go through the wall, another 90 to go up above the roof, total length of pipe about 20 feet.
This Waterford, a 43,000 BTU stove, is nowhere near the performer that my Resolute was. This stove is very difficult to light. I have a stove top thermometer and it has almost never gotten over 500 degrees. Often it is hard to get it up to 400 degrees, no matter how dry the wood is or how small it is split.

Next year I am going to build an addition and get a new, big wood stove. I was down at the Jotul dealer in Asheville and told him about the Waterford. He said that I had screwed up the pipe install, as the new, or, after 1989, EPA compliant wood stoves did not do well with two 90 degree bends in the pipe. In fact, he was surprised that the stove worked at all.

Is this true? Based on what he told me I am planning a vertical run of pipe for the new stove with no bends.

 

[pen]

The new stoves are very dependent on draft. The 2, 90 degree bends do slow the draft and a straight shot is significantly better.

However, with 20 feet of length, I'm surprised you couldn't get the stove hotter if the wood is well seasoned. Is the chimney masonry or SS. What's the diameter of the chimney?

You mentioned the wood is seasoned, but what sort of species are you usually burning? How long has the wood been split and stacked before it sees the stove?

pen

 

[webby3650]

You mention 2 90's. Did the stovepipe change to chimney once it met the wall? Or was it stovepipe all the way to the top? There should have been a Tee at the bottom rather than a 90 and everything from the wall out should be class A chimney or a masonry chimney.

 

[Simonkenton]

Here is the little Waterford. Six inch pipe goes from the stove, up and through the wall. At the outside of the wall there is a cleanout thimble. This makes it easy for me to sweep the pipe, I unscrew the bottom of the thimble and run the brush right up to the top of the pipe. The interior pipe I disassemble and take outside to clean.
Outside the house, the pipe is all double wall stainless steel pipe.

I did the exact same install with the 1988 model Resolute down in Georgia in 1988. That wood stove was a great stove! I have read some bad things about the Vermont Castings on this forum today. Wie schade, because in 1988 Vermont Castings was making some great wood stoves Very sad.


Notice some ashes on the hearth. As I told someone on another thread, my girlfriend is the official hearth sweeper. When I took this pic 8 years ago she hadn't moved in yet. Back then, I swept the hearth about twice a year. Every time you open the door of the Waterford ashes come out, it doesn't bother me. I tell you what, that girl sweeps the hearth every day.

I use locust, oak, and black walnut in equal amounts. The wood has been split and stacked and under cover for at least a year, some of it for 2 years or more. I use very dry white pine kindling to start the stove. Still the stove is hard to light and hard to get up to high temp.

I have to split the wood small, perhaps to 2 or 3 inch diameter, and then set it near the stove for 24 hours to get it hyper-dry to get good heat out of this stove.

I was spoiled by my good old Resolute back in Georgia, not to mention the Sotz that I ran for several years. That Resolute was very easy to light. It burned green wood with no problems.
In fact, with that Resolute, I would always cut down an oak tree in November just so I could have green wood. When it was 11 pm I would load the little Vermont Castings up with green wood for an all night burn, that thing would hold good fire for at least 6 hours that way.

With the little Waterford, it doesn't like green wood at all. If you should put some wood in there that has only been curing for about 6 months, the temp drops to about 300 degrees or even less. It does not burn the wood well, and after an hour or so the fire box will be half full with glowing coals and there is no room to add more wood.
The Resolute down in Georgia would burn green wood right down to fine powder ash, no problem.


(broken image removed)

I know this looks like not much of a wood stove installation. It isn't much. This is a small log cabin and we focused on the stone fireplace, which is front and center in the living room.
We wound up sticking the wood stove in the corner of the kitchen. The fireplace looks great but the poor Waterford is left hanging out to dry.
Which is why I am building an addition and the new wood stove will be the center piece of it with a real pretty, big, stone hearth.

 

[oconnor]

As a rule of thumb, each 90 degree bend decreases your effective chimney height between 2-5 feet. Most consider 2-3 to be a better estimate. So you are essentially dealing with a 15 foot flue. On the terminology side, what you have outside is Class A factory built chimney. Double wall pipe can be a confusing term, as most refer to the interior connector pipe as double or single wall.

Is the outside chimney a 6" flue? Also, make sure the cap isn't clogging up - the green wood could clog that quickly.

As far as green wood goes, an EPA stove isn't going to burn wood well that has over 25% moisture content. That is essentially the point behind EPA stoves. Green wood does last all night, but it does so by smouldering, and sending unburnt gasses up the flue. That is the pollution part that the EPA specs are trying to control. If you are working with softer maples and birch, 6-8 months may be enough to dry it, but with harder species, especially oak, it can take 2 years.

In the end, you have a draft issue. Draft needs heat, air, and a clear path. External Class A chimneys don't hold heat really well. Try running the stove to a hotter temp before you turn down the air and keep the green wood for another year. I doubt your cabin is air tight enough to be restricting air pressure based on your description.

Less turns in the flue might provide better draft. You could consider adding another section of Class A chimney to make up for it.

 

[Simonkenton]

I'm not burning green wood. The cabin is pretty air tight but not so air tight as to restrict air flow to the stove. In fact I have an exterior air intake for the fireplace which I have left open for the wood stove, and it didn't make any difference.

Oconnor that is a great idea to add a section of pipe. I will try that for next year. Thanks a lot.