How do I connect my outdoor air intake in the floor to the air intake on the bottom of my wood stove

[Serendipity]

Last winter, my husband and I invested in a Jotul 600 woodstove to serve as the sole source of heat for our new home. As recommended by the manufacturer, we installed an outdoor air intake beneath the stove. It is a 10-cm diameter pipe that opens into the basement below, which itself is rather poorly sealed by two flimsy garage doors (the better to let outdoor air in, we tell ourselves). The basement (which is actually at ground level on the side with the garage doors) also has two vents to allow air to circulate in the basement.

When our Jotul vendor installed the woodstove, the technicians did not connect our outdoor air intake pipe to the air intake on the bottom of the woodstove. When we asked them why not, they first told us that doing so would reduce the efficiency of the stove. When we spoke with another person from their team, we were told that our stove was not designed to be directly hooked up to the outdoor air intake, and that simply having the source of outdoor air "near" the bottom of the stove was enough.

Getting two different explanations was frustrating and unconvincing, so I contacted Jotul directly, at their headquarters in Norway. Unfortunately, they directed me back to my local installers. Today the installers came by the house for another matter and maintained their story about not being able to hook up the outdoor air pipe to the stove's air intake. After they left (I should have done this beforehand), I used a mirror to look at the bottom of the stove and found a 9-cm diameter hole.

What is keeping me from connecting this hole to the 10-cm diameter hole in the floor with fireproof tubing? Is there a risk? Can I do it myself? Does it need to be sealed in an airtight fashion? What kind of tubing do I need, exactly? Can you confirm that this is indeed the best thing to do? Why are the installers saying that the stove isn't designed for this?

Insulation issues aside (let me just say this again: we have a HOLE in our floor), I am particularly concerned about this because we have a heat-recovery ventilation system, and on more than one occasion I have been informed that woodstoves and HRVs can conflict with one another, causing toxic gases to flow into the house rather than out the stovepipe.

I appreciate your taking the time to read this.

Thanks very much for any help!

By the way, the Jotul 600 did a great job of heating our 1800 square-foot home all by itself last winter (despite the hole in the floor). What a luxury!

 

[begreen]

Welcome et bienvenue. I'm glad you are enjoying the F600. It's a very nice stove.

Yes you can do this yourself. There is a Jotul outside air adapter kit that has the start collar to attach flexible metal pipe to the stove.

 

[Serendipity]

Thanks so much for your reply. I've looked into the adapter, and in the F 600 spare parts list it is described as "Outside air kit(Only USA/Canada)." I don't really know what that is about, but there is also a product called "adapter outside air" that is not restricted to the US & Canada. I'm looking into it.

 

[pen]

I searched and searched online and couldn't find a thing on either other than what little bit is in the parts list. I'd say the Jotul dealer should be able to straighten you out but I ask that you come back and report what you find when you do. I'm betting the 2 are made out of different material but could be wrong.

pen

 

[Don2222]

Hello

Let me tell you what I have found from experience with OAKs. I have a wood pellet stove. The outside air intake goes into the stove and inside the bottom of the stove is an opening to mix heated room air with the outside air. All the manufacturer said was "Do Not Block" the room air opening inside the stove! Since I am an engineer, I needed an explanation to understand why and no-one would or could give it to me!! So I got some aluminum and blocked the room air to see what they were talking about! This is what I found. The stove kept the house warmer and more comfortable in the very cold dry months of winter. It seemed better and less drafty. However during the spring and fall when I just wanted some low heat, it did not work very well. On days when the outside temp was mild and the air was damp, when I had low fire, the wood did not burn as well and I got clinkers and a jam up. So having the outside air under your stove mixing with some inside heated air is a good way to do it! So the installers have a point, however wood fires are not as sensitive as wood pellet fires so the wood fire would burn ok. If you are drawing damp air from the garage, then mixing with warm room air is also good.

So that is my 2 cents from experience.

Good luck with whatever you decide to do.

 

[jimbom]

I do not have a Jotul or a HRV, so my comment is uninformed as to your specifics.

My mental summary is you have a new Jotul and it did a great job heating your house. You are, however, concerned with the makeup air opening in your floor.

A screen over the hole will keep insects out of the living space.

A metal plate that you can slip over the hole next winter would demonstrate the need for outside air. If the stove functions well in various conditions with the plate in place, I might seal the opening.

You mentioned garage doors in the basement. If the basement is used as a garage, consider fire and carbon monoxide issues related to an opening in the floor of the living space.

 

[Todd]

I find it kind a strange that the dealer is reluctant to install the OAK. You already have the hole in the floor, you just need the adapter. Go to the dealer and tell them to order an adapter and hook it up. The idea of an OAK is to use that outside air for combustion instead of the already heated room air which also helps for a tight house or a stove that has to compete for air with other appliances or fans. It won't do it as well if it's not connected. Both of my stoves are directly hooked up to outside air and I can tell you it does make a difference.

 

[Todd]

You mentioned garage doors in the basement. If the basement is used as a garage, consider fire and carbon monoxide issues related to an opening in the floor of the living space.

Good point. If your starting up a car in that garage the nasties can leak up into your living space. You might want to consider running the OAK out to fresh air.

 

[Serendipity]

Thanks to all for your help & suggestions. I'll be going back to the installer's with the Jotul parts list and will be sure to report back about what happens after that.

 

[begreen]

Thanks so much for your reply. I've looked into the adapter, and in the F 600 spare parts list it is described as "Outside air kit(Only USA/Canada)." I don't really know what that is about, but there is also a product called "adapter outside air" that is not restricted to the US & Canada. I'm looking into it.

Just a guess, but the difference might be in the pipe size. I think the US size is 4" which is a common metal dryer duct size? The universal version may be metric and sized for a common pipe in Europe (90mm?)

 

[Serendipity]

Quick update: I haven't been to see the installer yet, but I did get this reply from another source:

"A ducted supply of outdoor air for your stove is not necessary or desirable. See:
http://woodheat.org/outdoor-air-supplies.html "

Any thoughts about this?

 

[begreen]

on more than one occasion I have been informed that woodstoves and HRVs can conflict with one another, causing toxic gases to flow into the house rather than out the stovepipe

If you have gone an entire season without an issue, what is the concern? Usually connecting the OAK is to resolve a specific problem. We have seen it to be helpful for example with some basement stove installations where the flue connection was less than ideal and there were competing appliances in the same area (furnace, hot water heater, clothes dryer, bathroom fan, etc.) If you are noticing a change in the stove behavior when the HRV is operational and the kitchen fan + the clothes dryer are operational, then connecting the OAK could be a good idea. When the stove is going, try covering the hole temporarily with a board or a book. Then turn on everything that exhausts air from the house and see if the fire is burning differently. If not, I would just close up the hole.

Regardless, I'm not a fan of an open hole in the floor and would just connect it to a proper OAK. The reason being that I don't want cold air entering the house when the stove is off and I don't want to give vermin their own private entrance. And second, the question was brought up about this hole being direct to the garage. That is a genuine concern and a good reason for either sealing the hole or running the OAK duct through it, to the outdoors, with a rodent screen at the end. FWIW, OAKs are required in our state.

PS: What type of HRV is installed? Is it a simple fan or an air to air heat exchanger?

PPS: More interesting reading on the topic and a response to the woodheat article:
http://www.chimneysweeponline.com/hooa.htm
http://www.chimneysweeponline.com/hooa3.htm

 

[Serendipity]

Regardless, I'm not a fan of an open hole in the floor and would just connect it to a proper OAK. The reason being that I don't want cold air entering the house when the stove is off and I don't want to give vermin their own private entrance. And second, the question was brought up about this hole being direct to the garage. That is a genuine concern and a good reason for either sealing the hole or running the OAK duct through it...

These are exactly my concerns. The woodheat.org articles argue that closing up the hole completely would be the best option because of the risk of reverse flow, but I must admit that I am still tempted to get the OAK since we do have an air-tight house and also, frankly, because we put the hole there for a reason and we may as well use it for that reason. Our HRV has air-to-air heat exchange. I feel like taking our precious heat-recovery-exchangered air and burning it is a waste, however small.

Also, last winter we couldn't judge the performance of the stove because we actually had a gigantic hole (a missing wall) between the ground floor and the basement/garage. The wall is now there, giving us a fully enclosed living area, but we haven't made a fire since the wall went up.

Thanks for the links.

 

[begreen]

From what you've posted I would go ahead and properly install the OAK to the outdoors through the garage space. If nothing else it will give you peace of mind.

PS: Please hang around and let us know how this works out. And if at all possible post some photos of this nice stove and its installation.

 

[Highbeam]

The woodheat articles and viewpoint on this is, well, wrong. It has long been ridiculed by many. Pay no attention to their position.

There have been many OAK debates with good information from both sides of the argument. In my state it is required, as in no approval without it hooked up. Hearthstone has a setup that provides a 100% sealed connection allowing only outside air for combustion. You can see my hookup details in the links in my signature line.

I have been very happy with my OAK and would recommend it to anyone even if the law didn't require it. It can't hurt anything. It may not help but it has never hurt an install to have an OAK.

 

[Don2222]

Hello
There are many good points here. So the best answer is to use it like it is only in the shoulder seasons to mix warmer room air. Then connect it directly to the stove in the cold dry winter months and block it completely in the summer or when off! Also getting direct outside air with a bug screen is the best way to go!!

 

[Serendipity]

Here's an update: we were finally able to order the outside air kit from the installer using the part number from the parts list. We installed it last week and have been building a fire almost every day for the past week. We can't tell the difference as far as the behavior of the fire, but we are glad not to have the cold, polluted air from the garage mixing with the clean, warm air from inside the house. Thanks to everyone for suggestions and help.