Backdraft on Windy Warm Day

linkman2448 · Post by **linkman2448** » Sun. Dec. 28, 2008 3:29 pm

After reading this forum and seeing all the experienced people that are on this site, I have an issue that I need help with. I have installed a new Keystoker K-6 boiler and have been burning it for 1 month. It is in series with my propane boiler and the chimney is an 8" Simpson stainless duraplus that is on the outside wall of the house. I have a problem with backdrafts on windy warm days and wanted to know if anybody had any ideas on how to solve it. I assume that this occurs because the boiler is at idle with the warm temps and the chimney must be cooling down to allow for the backdraft. Any help is appreciated.
Thanks

Flyer5 · Post by **Flyer5** » Sun. Dec. 28, 2008 3:38 pm

linkman2448 wrote:After reading this forum and seeing all the experienced people that are on this site, I have an issue that I need help with. I have installed a new Keystoker K-6 boiler and have been burning it for 1 month. It is in series with my propane boiler and the chimney is an 8" Simpson stainless duraplus that is on the outside wall of the house. I have a problem with backdrafts on windy warm days and wanted to know if anybody had any ideas on how to solve it. I assume that this occurs because the boiler is at idle with the warm temps and the chimney must be cooling down to allow for the backdraft. Any help is appreciated.
Thanks

How much higher is the chimney above the roof line ? Are there other buildings or trees close enough that can cause rotors or turbulence in the air . How high is the chimney ?Oh yea ,Pics of the chimney would be good as well ?

linkman2448 · Post by **linkman2448** » Sun. Dec. 28, 2008 3:49 pm

I have the chimney installed according to the instructions that Simpson provided with the pipe. It is 4 ft above the roof penetration and 2 ft about the highest point within 10 ft. I will send you some pictures soon.

linkman2448 · Post by **linkman2448** » Sun. Dec. 28, 2008 3:50 pm

Oh, one more thing. The closest structure higher than the chimney is about 300 yards away.

Flyer5 · Post by **Flyer5** » Sun. Dec. 28, 2008 8:06 pm

What temp is the boiler running ?

PC 12-47E · Post by **PC 12-47E** » Sun. Dec. 28, 2008 8:39 pm

The wind is starting to pick up 25 kts.+ and gusting harder...

The wind direction is all over the compass.

My Dwyer MK II model 25 is going up and down. I have it set at .06 . low reading is .00 and then it pegs at the max setting of .06. Outside temp is 48*F. We have a very small amount of sulfur smell in the house. This smell does not last more than 60 seconds.

The CO detectors have not shown a problem. The stack temp is low @ 125* F. I have opened two rooms that are not heated, about 1,000sq/ft. and this old house is VERY drafty! 200++yrs old.

Do you think I should run the stove harder to get more heat up the flue, ( 8x8) tile and 30 feet, or just open a window or two?????

The manometer only stays at .00 for a split second. Average is about .25-.30....

Thanks to all, R.S.

linkman2448 · Post by **linkman2448** » Sun. Dec. 28, 2008 10:13 pm

The boiler is running around 170. Do you think that I am getting turbulence from the peak of the house which is 12 feet away from the stack and just above the height of the pipe by 1 ft?

CapeCoaler · Post by **CapeCoaler** » Mon. Dec. 29, 2008 8:52 am

If the wind direction comes from over the roof peak it could be in a zone of turbulance.
I ended up putting an extra 2 feet of pipe on my chimney to get it into an area of clear air.
The normal wind direction pushes against a flat wall which the chimney is located on.
This created an area of higher preassure at the cap.
This high pressure combined with the short length of the chimney caused poor draft, even though the top was properly located 3 feet over the peak.
Just because the book says it should work, doesn't mean it will in your enviroment.
Getting the top into clear air or maybe a specialized top will solve the backdraft.

sde48 · Post by **sde48** » Mon. Dec. 29, 2008 9:11 am

When I installed my AA130 in a garage I started with a 6 inch RC draft conrol. I jumped from 5 inch pipe at the boiler to a 6 in. pipe to a 8 in. existing selkirk insulated chimney. My garage faces due south and that is where I get my strongest wind. With the garage doors closed and about a 10 mph wind from the south the damper would not hold the draft below .08-1.0 wc. I fixed the problem by going from 5 in. to 8 in. at the boiler and installing a 8 in. rc control 2 ft. above the boiler on a 45 degree angle pipe to the chimney. Now I can get a almost constant .03-.05 on the draft with no "banging " full open on the draft control. stan.

linkman2448 · Post by **linkman2448** » Wed. Dec. 31, 2008 6:06 pm

I have added a 3 ft section of pipe and with all the wind we have had today it appears to be working. Thanks for all your help.

rberq · Post by **rberq** » Wed. Dec. 31, 2008 6:23 pm

linkman2448 wrote:2 ft about the highest point within 10 ft.

Glad to hear you have solved it. Apparently the standard minimums weren't quite enough in your case. That should be useful information for other readers in the future. If there's one thing I have learned from this forum, it is that there's no such thing as one-size-fits-all.