Does Outside Air increase the Efficiency of woodstoves?

[sneefy]

the OAK allows you to control where the air your stove needs comes from.

This is key.

But it might increase the efficiency of the home by reducing the air turnover in the house.

Exactly. From an airflow perspective, assuming 100% of combustion air came from the OAK, (which isn't completely accurate, but stay with it for a thought exercise), think of the airflow of the stove as being fully outside the home. It comes inside only as an incidental in a closed loop. with source and exhaust outside the home.

- Starting with the title being a declarative statement as if it were fact.

Which is not only incorrect, but a question nobody is asking.

Have you also considered the difference in air humidity between inside and outside?

And oxygen density. 'Warming of combustion air' is not relevant as it's consumed chemically.

Same amount of air goes in and out of the house regardless

Again, assume (for the sake of argument) it's a fully closed loop. None of the air mixes with the conditioned space. It's fully 'outside' as the open ends of the loop are outdoors.

 

[robllachance]

Yes, the original post pointed out that if a house is too tight to draft effectively OAKs would be a benefit in controlling operation of the stove. The original post was about the efficiency gain (in this case near zero) given that the house was drafty enough to allow operation of the stove controls effectively. There is absolutely new construction that would be difficult to operate a wood stove in without an OAK since there isn't enough air leaking in.

 

[robllachance]

This is key.

Exactly. From an airflow perspective, assuming 100% of combustion air came from the OAK, (which isn't completely accurate, but stay with it for a thought exercise), think of the airflow of the stove as being fully outside the home. It comes inside only as an incidental in a closed loop. with source and exhaust outside the home.


Which is not only incorrect, but a question nobody is asking.


And oxygen density. 'Warming of combustion air' is not relevant as it's consumed chemically.

Again, assume (for the sake of argument) it's a fully closed loop. None of the air mixes with the conditioned space. It's fully 'outside' as the open ends of the loop are outdoors.

You missed the point. Draw the picture.

 

[sneefy]

You missed the point. Draw the picture.

I did not. You started from a false premise and added a couple more bad assumptions.

 

[bholler]

You missed the point. Draw the picture.

What is the point? We know as long as the stove has enough makeup air it doesn't care where it's coming from. It's going to burn the same regardless. But if that stove is pulling air out of the living space for combustion that air then needs to be replaced by air being sucked into the home from outside. In some homes the air exchange is high enough this won't really matter but in other it certainly will.

As long as outside air can be easily run there is no downside to it at all so why not do it? In my case because it's a basement install it's not easy at all so I don't have one now. But I certainly would if it was easier.

 

[Poindexter]

I think of a wood stove with an OAK, perhaps not 100%, but nearly the same as mamalli

The point is that the temp differential between outside and inside doesn't matter.

You are welcome to come to Fairbanks for the winter. You may camp in a tent with no temperature differential in my back yard as long as you like. I will be inside my house with a wood stove and a notable temperature differential between indoor and outdoor air.

Peace out.

 

[30WCF]

It would be interesting for someone that has one installed, but doesn’t actually need it, to do some experimenting for us.
I’m sure there are lots of ways to measure efficiency. Burn time, wood weight/volume, air turnover, BTU and temperature. Even those can defined by personally imposed references or definitions. Is burn time useable heat, to what degree is useable under what conditions? That will be different for everyone, or is burn time just an easy relight? That’s not at debate here, but some about of this is personal vs just numbers on an excel doc.
So, if a guy with an OAK burned and monitored the temp of an isolated back bedroom for a week of steady temps, then ran the same test with the OAK disconnected to see if there was a gain in temperature due to how air was exchanged. That may be enough for that person to say the OAK was more efficient and beneficial at distributing heat throughout the home.

 

[Prometeo]

I did a "test" and when I did with oak I easily reached and exceeded 25 C without oak I managed to get a maximum of 23-something let's say 23.5 the thermometer was in position away from the stove and protected from radiation of the stove. In my case oak also helps maintain a minimum amount of humidity, in my opinion oak helps by 15 percent, I don't think I'm exaggerating because it is reportable. My house is very airy, I have a direct door to the outside, without double door.

 

[twd000]

does this analysis also apply to gas-fired appliances?

I have a very efficient propane furnace, and propane water heater, and they both have dedicated outside air intake pipes

 

[robllachance]

does this analysis also apply to gas-fired appliances?

I have a very efficient propane furnace, and propane water heater, and they both have dedicated outside air intake pipes

Yes In fact the unvented units you'll find have potentially very high efficiencies (95+%) while the vented units are less so (80-85%)

 

[robllachance]

Yes In fact the unvented units you'll find have potentially very high efficiencies (95+%) while the vented units are less so (80-85%)

But this isn't an apples to apples comparison either

 

[bholler]

Yes In fact the unvented units you'll find have potentially very high efficiencies (95+%) while the vented units are less so (80-85%)

Yes if you ignore air quality and healtg effects unvented units are great

 

[bholler]

But this isn't an apples to apples comparison either

Why not? We are talking about a heating appliance that is burning a fuel and needs an air supply to do so. That air either comes from inside the home or out.

 

[twd000]

Yes In fact the unvented units you'll find have potentially very high efficiencies (95+%) while the vented units are less so (80-85%)

both units in question are 95+% efficiency and vented

 

[robllachance]

both units in question are 95+% efficiency and vented

Why not? We are talking about a heating appliance that is burning a fuel and needs an air supply to do so. That air either comes from inside the home or out.

Because unvented units expell their "flue gases" inside

 

[joop]

your all wrong, you can't handle the truth lol

 

[bholler]

Ok I thought you were saying the vented units are not apples to apples with a woodstove. Nevermind. But there are plenty of condensing units that are vented and 95%

 

[Prometeo]

@robllachance
your research is good but I didn't understand if you only focused on the efficiency of the stove, or the efficiency of the stove inside the house, in this last case go into detail, evaluate, that it is unlikely that each of us will give the exact quantity of air, which will be in deficiency or in excess, in both cases it will be a loss evaluate altitude, do 2 cases at least low altitude and high altitude, also considers an average efficiency of the stove, and I think this will lead to some relatively reasonable data and you will have done it

 

[River]

Outside air does not increase the efficiency of woodstoves.

What, exactly, do you mean by "efficiency"? Please define the same.

 

[robllachance]

What, exactly, do you mean by "efficiency"? Please define the same.

technical definition of efficiency, heat brought into house vs heat lost to, for example flue temperature

 

[bholler]

technical definition of efficiency, heat brought into house vs heat lost to, for example flue temperature

Ok but in that you need to factor in the heat taken out of the house in the form of combustion air as well. So there is no way they are equal. BTW that is not the only technical definition of efficiency at play. There is also combustion efficiency.

 

[sneefy]

I'm glad the OP isn't engineering medical devices.

 

[Prometeo]

technical definition of efficiency, heat brought into house vs heat lost to, for example flue temperature

Without oak efficiency is reduced distant rooms suffer even more from drafts, I don't know, however, if for example CAT stoves, they suck in less air and therefore little changes with or without oak

 

[Hoytman]

Outside Air Connection=OAC


Not outside air konnection

 

[bholler]

Outside Air Connection=OAC


Not outside air konnection

Outside air kit is where oak is from.