chimney negative pressure problem

Post Reply
 
User avatar
keegs
Member
Posts: 318
Joined: Sat. Dec. 24, 2016 7:38 pm
Location: Bridgewater, ME
Hand Fed Coal Stove: Chubby (main floor)
Coal Size/Type: nut
Other Heating: Vermont Castings Resolute (basement)

Post by keegs » Thu. Nov. 07, 2019 8:26 pm

I recently had a cap installed on my two flue chimney. The one cap covers both flues.

One flue serves a stove (Chubby) in the living room and the other is meant to serve a boiler in the basement. The basement flue is not in use at this time.

Right now I'm burning wood in the Chubby. Apparently I have a negative pressure situation which is allowing the exhaust from the Chubby to get sucked down the adjacent cold flue into the basement. I have a couple of plastic bags filled with rags plugging up the basement flue thimble and it seems to be doing the job.

I looked around online at thimble plugs and the prices are all over the place. Can anyone recommend a reasonably priced thimble plug? Thanks in advance... any other recommendations are welcome as well.

 
User avatar
tsb
Member
Posts: 2043
Joined: Wed. Jul. 30, 2008 8:38 pm
Location: Douglassville, Pa
Stoker Coal Boiler: Binford 2000
Hot Air Coal Stoker Stove: LL Pioneer top vent
Hand Fed Coal Stove: Saey Hanover II
Baseburners & Antiques: Grander Golden Oak , Glenwood # 6
Coal Size/Type: All of them

Post by tsb » Thu. Nov. 07, 2019 8:40 pm

If you have a cleanout door for the flue, just keep it open till you need to use it.

 
User avatar
McGiever
Member
Posts: 8454
Joined: Sun. May. 02, 2010 11:26 pm
Location: Junction of PA-OH-WV
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: RICE,PEA,NUT,STOVE /ANTHRACITE and EGG / BIT
Other Heating: Ground Source Heat Pump and some Solar

Post by McGiever » Fri. Nov. 08, 2019 12:14 am

Short stove pipe inserted into thimble, then a metal stove pipe cap on that.

 
User avatar
keegs
Member
Posts: 318
Joined: Sat. Dec. 24, 2016 7:38 pm
Location: Bridgewater, ME
Hand Fed Coal Stove: Chubby (main floor)
Coal Size/Type: nut
Other Heating: Vermont Castings Resolute (basement)

Post by keegs » Fri. Nov. 08, 2019 3:16 am

Thanks guys. I didn't put in a cleanout for the basement boiler flue. I saw the chimney thimble cap with the crimped end online and I have a short piece of welded flue pipe that fits pretty tightly in the thimble. I might even mix up some refractory cement to fill in any voids.

Visit DS Stoves

 
User avatar
coaledsweat
Site Moderator
Posts: 12059
Joined: Fri. Oct. 27, 2006 2:05 pm
Location: Guilford, Connecticut
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

Post by coaledsweat » Fri. Nov. 08, 2019 7:05 am

When capping dual flues there should be a baffle between them.

 
crazy4coal
Member
Posts: 524
Joined: Wed. Feb. 13, 2008 8:29 pm
Location: Sussex County N.J.

Post by crazy4coal » Fri. Nov. 08, 2019 8:09 am

Take a wad of fiberglass insulation and ball it up tight and stuff it in there, it'll swell up and be air tight. Cheap and easy. I did it with mine and it works great.

 
User avatar
keegs
Member
Posts: 318
Joined: Sat. Dec. 24, 2016 7:38 pm
Location: Bridgewater, ME
Hand Fed Coal Stove: Chubby (main floor)
Coal Size/Type: nut
Other Heating: Vermont Castings Resolute (basement)

Post by keegs » Fri. Nov. 08, 2019 3:47 pm

Okay.. I went with the pipe and cap idea. I thought it might hold up a little better. I mixed up about 2 cups of refractory cement and troweled it between the pipe and the thimble as best as I could. I had about a 1/2 " gap here and there that needed filling.

 
User avatar
freetown fred
Member
Posts: 24381
Joined: Thu. Dec. 31, 2009 12:33 pm
Location: Freetown,NY 13803
Hand Fed Coal Stove: HITZER 50-93
Coal Size/Type: BLASCHAK Nut

Post by freetown fred » Fri. Nov. 08, 2019 4:56 pm

Ya got a piece of aluminum foil over the baro?

Visit DS Stoves

 
User avatar
keegs
Member
Posts: 318
Joined: Sat. Dec. 24, 2016 7:38 pm
Location: Bridgewater, ME
Hand Fed Coal Stove: Chubby (main floor)
Coal Size/Type: nut
Other Heating: Vermont Castings Resolute (basement)

Post by keegs » Fri. Nov. 08, 2019 8:35 pm

freetown fred wrote:
Fri. Nov. 08, 2019 4:56 pm
Ya got a piece of aluminum foil over the baro?
No baro ... rather a 6" ID clay thimble through the basement wall to an (unused) chimney flue. This unused flue was drawing in smoke from an adjacent flue and dumping the exhaust into the basement. I capped a short piece (about 18") of 6" pipe and set that into the thimble and packed any gaps between the thimble and pipe with refractory cement.

 
User avatar
freetown fred
Member
Posts: 24381
Joined: Thu. Dec. 31, 2009 12:33 pm
Location: Freetown,NY 13803
Hand Fed Coal Stove: HITZER 50-93
Coal Size/Type: BLASCHAK Nut

Post by freetown fred » Fri. Nov. 08, 2019 9:17 pm

In your other post, ya mentioned a baro in the chubby??? THE baro or A baro???

 
AllanD
Member
Posts: 40
Joined: Sun. Feb. 10, 2019 5:16 pm
Hand Fed Coal Stove: HAND FIRED HARMON
Coal Size/Type: STOVE
Other Heating: Oil fired hotwater baseboard

Post by AllanD » Sat. Nov. 09, 2019 6:06 pm

I would say what is more likely is that Your "draft" is creating a slight negative pressure and the easiest path to equalize that pressure is via that unused flue.

I would cap that unused chimney at the top.

 
User avatar
keegs
Member
Posts: 318
Joined: Sat. Dec. 24, 2016 7:38 pm
Location: Bridgewater, ME
Hand Fed Coal Stove: Chubby (main floor)
Coal Size/Type: nut
Other Heating: Vermont Castings Resolute (basement)

Post by keegs » Sat. Nov. 09, 2019 6:31 pm

AllanD wrote:
Sat. Nov. 09, 2019 6:06 pm
I would say what is more likely is that Your "draft" is creating a slight negative pressure and the easiest path to equalize that pressure is via that unused flue.

I would cap that unused chimney at the top.
The draft in the active (adjacent) flue is creating negative pressure inside the house. Capping the basement thimble (the idle flue) isn't the best option but it seems to be working.

Post Reply

Return to “Coal Bins, Chimneys, CO Detectors & Thermostats”