house stack effect

[JA600L]

Hey guys,
This term gets used a lot on here. I've been researching it a lot as I believe my house is suffering from it. I am heating from an insulated basement. Opening the door without caution sends a little smoke directly to the upstairs. In the summer I get reverse draft and smell.

One issue I have is ductwork in the ceilings upstairs. The attic floor has been air sealed as well as duct joints to the best of my ability. It has 18" of blow in insulation. I have new windows as well. Could duct work in the attic cause this condition? The attic door is insulated as well.

 

[Avalonolympic]

Same I have stack house effect. When I load wood into the stove you can smell the smoke up stairs. The house is not air tight. The house draws the air away from my stove right up the stairs. I just bought a outside air kit yesterday. Going to install this week I hope.

 

[JA600L]

Same I have stack house effect. When I load wood into the stove you can smell the smoke up stairs. The house is not air tight. The house draws the air away from my stove right up the stairs. I just bought a outside air kit yesterday. Going to install this week I hope.

That's kind of what I'm thinking too. I'm just not sure how I'm going to hook mine up from the basement. I think the real problem is the heat moving to the colder area upstairs very quickly.

 

[begreen]

Does the stove have an OAK connected?

 

[FPX Dude]

I went around upstairs with a light piece of plastic taped to ceiling in various places to see where the air was leaking out. Found that whole house fan louvers was an issue AND the 6" vent for the gas fireplace (which produces no heat anyway, and we don't use) were the culprits. Got an insulated velcro cover for the fan and plugged the vent and dramatically reduced the stack effect. Also, made the house less drafty.

 

[begreen]

Good tips. Older unsealed recessed can lights can also leak a lot of air.

 

[JA600L]

I plan on installing an oak in the future. I have a whole house fan as well. I installed window film over the bottom of it, put a blanket on top of the louvers, and blew in over top of it. My idea with ducts are they now have a system where they come in and seal your ducts from the inside with some special tooling and solution. I am debating if that is worth doing for both a/c and to reduce the stack effect with the Woodstove. There are no ceiling lights.

I have always thought my house had a strong convective flow to it because it moves air up the stairs pretty aggressively. Maybe what I'm really seeing is air being sucked up my ceiling vents. As the duct work is always cold in the attic, I'm sure the heat is going to work hard to get up there. Maybe I should be investing in some ducts with louvers. Do they make something like that?

 

[begreen]

Are the attic vents only for A/C or also for heating?

 

[RustyShackleford]

I noticed an effect in my house - when installing a new bathtub, and exposing a 1 sq-ft or so hole in the subfloor where the drain/overflow assembly passes through to the crawlspace - of a strong draft coming up from the crawlspace. I turned off the HVAC and any other mechanicals that conceivably could be causing this draft, but it remains. The truly odd thing is that I recently had my crawlspace "encapsulated", so theoretically there should be nowhere for all that air (that's rushing up into the house from the crawlspace) to be coming from. I'm going to try going down there with a stick of incense to see if I can detect what must be a leak in the encapsulation job; to do that, I need to somehow figure out a way to temporarily re-open a hole between the crawlspace and the house (the bathtub installation being complete).

 

[RustyShackleford]

Good tips. Older unsealed recessed can lights can also leak a lot of air.

Indeed. I replaced the trims - on my 6" Halo cans - with ones that are both airtight and reflective. So now they are airtight, plus I can use ordinary bulbs (instead of the much more expensive reflector type). In my opinion, it's a scandal that (at least at the time my house was built) these are so hard to find, as the save energy as well as saving the homeowner money or light bulbs. I had to mail-order mine: (broken link removed)

 

[RustyShackleford]

Found that whole house fan louvers was an issue ...

I realized that my whole house fan creates a completely un-insulated, and somewhat air leaking as well, 3ft-square hole in my ceiling. As considerable effort, I built a cover for it. It slides horizontally on drawer slides; they are tiled at a slight angle away from horizontal, so that as the cover slides into position, it also elevates about 1/2", pushing up against weatherstripping that makes the seal. The cover is also insulated with foam board. Needless to say, this thing was a pain to build, challenging my meager woodworking skills to the utmost. AFAIK, you can't purchase such a thing; and I would have been better off getting a furniture maker to build it for me.

 

[Avalonolympic]

I'm about to put in my OAK. Still staring at it. Nervous about putting hole in wall.
Want to also make sure this will help my issues.

 

[JA600L]

Are the attic vents only for A/C or also for heating?

A/c and heat pump. I also use it circulate air occasionally to filter.

 

[JA600L]

I'm about to put in my OAK. Still staring at it. Nervous about putting hole in wall.
Want to also make sure this will help my issues.

Issues or not I think it is a major plus to burn outside air rather then burn conditioned air.

 

[begreen]

OK. In that case the ducts should be tightly sealed at every joint and well insulated. I was thinking if AC only the register could be blocked off and then removed in spring, but that would be a bad idea if used in the winter.

 

[JA600L]

https://jet.com/product/detail/dd33...3eaeff81f1eb&gclid=CO7V6bjR8MgCFUmPHwodMIYBXQ

Anybody ever see this before?

 

[Sawmonkey]

I believe the stack effect is going to be determined by how many holes are coming into your home in your basement and how many holes are going into your attic. Your home has a negative pressure zone (basement) and a positive pressure zone (usually floors above your basement). I couldn't be way off but I think if you have more holes in the negative pressure zone you will have a bigger issue with smoke coming back into your home. The best thing would be having an OAK and for your venting to go through the highest point of the envelope of the house. I maybe a little off with my explaining but I'm pretty sure I'm close.

 

[JA600L]

The reason I think the vents are an issue is because the ducts are in a cold attic. This causes an area of low pressure in the ducts that cause hot air to rise rapidly. Then the hot air is cooled and falls out the same or other vents.

I have sealed all joints, wrapped the air handler, and the ducts are all covered in insulation.

 

[JA600L]

I spoke to the local hvac experts. They recommend that I install a 1" foam board in the return filter housing. That makes the most sense as it is a big hole in the ceiling right above the staircase. I'll try that first and see. I'll just have to remember to take it out to run the air handler.

 

[Boiler74]

Remember that you probably have two "chimneys" running from your basement to your attic. If you have supply registers and a return in your upper floor ceiling then you have two trunk lines running from the basement. Same principal at work as your stove's chimney. So you might be having air being pulled up those trunks from the lower floors. And that unsealed trunk line could be allowing air to escape inside the walls to lower pressure areas too.

 

[JA600L]

Remember that you probably have two "chimneys" running from your basement to your attic. If you have supply registers and a return in your upper floor ceiling then you have two trunk lines running from the basement. Same principal at work as your stove's chimney. So you might be having air being pulled up those trunks from the lower floors. And that unsealed trunk line could be allowing air to escape inside the walls to lower pressure areas too.

What do you suggest I do?

 

[Boiler74]

First you could drill a hole in the trunk lines and use incense to see if air is being pulled up. My guess is yes. Once that is established you could try to find a location that you could use metal and tape to temporarily block the trunk line. See if that helps.

 

[JA600L]

I added 3 ft of double wall insulated A-vent chimney today as per the recommendation of Ron at Woodstock.

It's hard to say this early, but I definitely feel like it had a much more robust start up. Before I started the fire I raked ashes and this time they seemed to go up the chimney instead of all over me like before. I put a piece of toilet paper in the door way. It had a very slight tug into the stove (all cold).

The stove got up to temperature very quickly. I usually have to help it and leave the door open. Not this time. If it runs this good at 55 degrees I can't wait to see it at 20.