Stove for 700sqf home

[Dmichigan]

All we are talking about is a test to determine if the stove is starving for air due to a tight house. Try starting a fire with all windows closed, then try again with the nearest door or window slightly open. Note if there is any difference in the fire.

I will give that a try. Its pretty warm out the last 2 days mid 40's that doesn't help.

 

[SpaceBus]

Where is @coaly when you need a good description of how wood stoves work.


It's not like you have a damper closed, it's like the fire is starving for air and it is going to pull that air from wherever is easiest. Due to the tightness of your house that happens to be the flue attached to the stove thereby making your house into a chimney.

Most stove manufacturers make an outside air kit to prevent this issue.

 

[coaly]

I will give that a try. Its pretty warm out the last 2 days mid 40's that doesn't help.

The reason you need an opening to the outdoors is to allow atmospheric air pressure into the intake air opening.

When you start a fire, hot exhaust gasses lighter than outside air rise up the chimney. This makes a low pressure area in chimney flue, pipe and stove. This low pressure area allows atmospheric air pressure to PUSH into the stove. This is the oxygen needed for the fire to burn in a closed box. The lowest pressure is measured at the stove collar, called draft. The greater the temperature difference inside and outside of the chimney, the stronger the draft. This is why the chimney is considered the engine that drives the stove.

Atmospheric air pressure in your case can't get into the building structure being very tightly sealed to the outside air. So the hot chimney depressurizes the house, starving the fire of oxygen. When a chimney is up to temperature, the low pressure area inside chimney flue may be strong enough to allow most homes to leak outside air into the home to support combustion. This air equalizing the pressure can come from bedrooms or areas far from the stove allowing cold drafts, migrating toward the stove. So a small opening close to the stove allows the colder air to be used by the stove and exhausted up the chimney. It is going to use the same amount of air, no matter where it comes from. You can see why very tight homes need an air intake. If you turn on any exhaust fans, clothes dryers, or vented appliances such as water heaters, furnace, or boiler connected to another chimney, or power vent, the mechanical exhaust can easily overpower the rising gasses from the stove, in extreme cases causing the chimney to act as the air intake for the entire home.

 

[BKVP]

The advantage of the FA kit it you won't, as Coaly points out, pull cold air from around doors, windows, outlets etc. The outside air is connected directly to the appliance. So when you burn wood, you choose...use air from the living quarters (you just heated) or outside air.

 

[Dmichigan]

I'd rather burn the outside air like my tankless water heater does. I still should add the extra few feet to the chimney tho. Another 36" will give me 14 foot and about 5 foot above the flashing, I think 5 foot is max unsupported so hope 14 foot is ok as I don't want to add braces to my steal roof.

 

[SpaceBus]

I'd rather burn the outside air like my tankless water heater does. I still should add the extra few feet to the chimney tho. Another 36" will give me 14 foot and about 5 foot above the flashing, I think 5 foot is max unsupported so hope 14 foot is ok as I don't want to add braces to my steal roof.

Yes, definitely extend the chimney as well. Are you saying all of the chimney is unsupported? I don't blame you for not wanting additional holes in the roof, but I bet it's not pretty when 25lbs of chimney pipe comes tumbling down in a windstorm.

 

[Dmichigan]

Yes, definitely extend the chimney as well. Are you saying all of the chimney is unsupported? I don't blame you for not wanting additional holes in the roof, but I bet it's not pretty when 25lbs of chimney pipe comes tumbling down in a windstorm.

From the ceiling support box I have a 48" now, about 16" of that is below the roof line. Does the flashing count as the last contact point? Or the support box seat?

 

[SpaceBus]

From the ceiling support box I have a 48" now, about 16" of that is below the roof line. Does the flashing count as the last contact point? Or the support box seat?

I'm not entirely sure with your install. My chimney has 5' above the final support, but I also have an extra 4' length and the roof kit. I would have put it on already but I ran out of time.

 

[Dmichigan]

Mine

I'm not entirely sure with your install. My chimney has 5' above the final support, but I also have an extra 4' length and the roof kit. I would have put it on already but I ran out of time.

Mine is a straight shot up through the roof.

 

[Dmichigan]

I've been wondering since the start of the build if I should install a Energy Recovery Ventilator, wonder if that would be enough air or just install an OAK too. This morning my CO2 alarm went off and said it was around 70 ppm. Apparently that's higher than the 50 ppm the health department says is high. It went off after a few minutes with a window cracked. Sealed it up to good apparently.

 

[Ashful]

I've been wondering since the start of the build if I should install a Energy Recovery Ventilator, wonder if that would be enough air or just install an OAK too. This morning my CO2 alarm went off and said it was around 70 ppm. Apparently that's higher than the 50 ppm the health department says is high. It went off after a few minutes with a window cracked. Sealed it up to good apparently.

OAK. Don't mess around.

 

[SpaceBus]

An ERV isn't a bad idea Just to get some fresh air in the house.

 

[Ashful]

An ERV isn't a bad idea Just to get some fresh air in the house.

Definitely. But for the sole purpose of combustion air, I don’t think you can beat the directly-connected OAK.

Merry Christmas, folks!

 

[begreen]

Definitely. But for the sole purpose of combustion air, I don’t think you can beat the directly-connected OAK.

Merry Christmas, folks!

It depends on the stove location. For some basement installs and homes built on a slab an ERV is a good option.

 

[Dmichigan]

So my OAK adapter plate will be here tomorrow ( dealer said to just throw on some 3" flex pipe..... it's a rectangle hole!) and also picking up a 36" pipe to extend to my max unsupported length with 14' of chimney. Hopping this makes it work a lot better. Still trying to figure the thermostat out. Anything under half the fire goes out and gets cold.

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

 

[moresnow]

Don't sweat the "just under half" setting. Your stat set point relates to your individual install conditions. Find your own sweet spot setting. It can vary quite a bit from one home to the next. Many are running at half or more as there low setting.

 

[Ashful]

Don't sweat the "just under half" setting. Your stat set point relates to your individual install conditions. Find your own sweet spot setting. It can vary quite a bit from one home to the next. Many are running at half or more as there low setting.

Yeah... on mine I can only use maybe 30% of the dial. Any lower and I can stall it. That’s normal.

 

[Dmichigan]

Thanks guys. On the OAK should I use the insulated duct after going through the floor to the crawl space and the regular metal flex duct behind the stove?

 

[Ludlow]

100% of the duct must be non combustible metal ducting. You could insulate it if you want with something such as fiberglass.

 

[Dmichigan]

Ok lots of things happened this month, I installed the OAK and also installed a 6" fresh air intake in the utility room for exhaust make up air. Glad I don't need the chimney for my air intake anymore lol. This has been a mild winter and easily getting 12 hours with 4, 6" and 2, 3" splits and rounds for overnight burns.

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

 

[Ludlow]

Nice!

 

[Dmichigan]

Full load of 15% dry maple. Getting a good 12 hours of heat before reloads 20's day and teens at night. Running the thermostat around 55~60%. Like how 2 logs get 2~3 hours of heat. Still getting to know what wood and what % of moisture gives what time and thermostat setting to use.

Go cat go