Hello to all from a person who just started burning wood this past season. I have read the posts on this forum for a little while and have learned a great deal along with realizing I have alot of the same questions as many of you. But I have a question that I have not seen addressed yet and I am not sure if its fact or fiction. I have a long ranch home that is approx. 2200 sq. feet and my stove is at the far end of the house in the living room. I have a free-standing Avalon Olympic with a blower. The biggest problem I had last season was getting the heat all the way to the other end of the house where the bedrooms are. I have been told by several people that if I had central A/C to have a return put in the room with the stove and it will more or less become central heat in the winter. I am getting a new central A/C installed in a couple weeks and I am debating on having an extra return added to the room with the stove. My A/C guy doesnt seem to think it would work well enough for the extra cost since the heat would probably be cooled off by the time it made it out in the other rooms. Does anyone have any experience or thoughts on this??
wood heat & central A/C
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Your A/C man is right. Typically the loss of heat due to duct losses makes this a sub-optimal solution. If there is a long hallway connected to the living room, sometimes the best solution is to place a fan on the floor at the far end of the hallway, blowing the cool air at floor level, towards the stove room. You can try a regular table fan or box fan on low speed to see how this work. Depending on the floorplan it can work fairly well at distributing the heat.
SlyFerret
Minister of Fire
I have a return up high on the wall about 8 feet from my stove. I thought that running the fan would help spread the heat around the house, specifically into the lower part of the split (my stove is on the mid level). Running the fan did absolutely nothing to move heat around my house. I'm thinking about putting in electric baseboard heat in the family room in the lower level. The stove heats the rest of the house just fine, but the lower level is just a bit on the chilly side (usually about 60 degrees).
Also, keep in mind that your HVAC system was designed exactly the way it needs to be in order to heat/cool your house effectively. If you start adding returns and vents elsewhere, you may find that you actually reduce the effectiveness or efficiency of the system as a whole.
BeGreen's suggestion is a good one. When trying to move heat around the house, move the cold air to displace the warm air to where you want it. The cold air is more dense, which is why it doesn't work as well to try move the warm air.
-SF
Also, keep in mind that your HVAC system was designed exactly the way it needs to be in order to heat/cool your house effectively. If you start adding returns and vents elsewhere, you may find that you actually reduce the effectiveness or efficiency of the system as a whole.
BeGreen's suggestion is a good one. When trying to move heat around the house, move the cold air to displace the warm air to where you want it. The cold air is more dense, which is why it doesn't work as well to try move the warm air.
-SF
Sometimes solving the problem with an electric heater at the far end is not a bad plan at all.
FWIW, I think code requires the return air duct to be at least 10 feet away from the stove.
FWIW, I think code requires the return air duct to be at least 10 feet away from the stove.
We recently completed a major remodel of our home, which included an entirely new central forced air electric heating system (no A/C, we don't need it here). When we were in the process of all that, I asked the HVAC contractor to install a completely separate, dedicated system that would more effectively distribute the heat from our woodstove. The stove's located in our "great room", and there are three bedrooms (including the master) on the same floor. Problem always was getting heat to those rooms. Upstairs, no problem, wide open, lofted. What I had them install is a simple set of ducts that connect to floor return registers in the most remote corners of the three bedrooms, leading to an inline variable speed fan, which then exhausts through a supply register in the hearth just behind the stove.
To make sure we're on the same terminology page, when I say "supply", I mean a register that delivers air to the space (blows a sheet of paper away when the fan's running), and when I say "return", I mean a register from which the system fan takes a suction (sheet of paper sticks to it when the fan's running).
My thinking in this was that if I take cool air from floor level in the remote room corners, and send it out to just behind the stove, then warmer, higher air will find its way in to replace the cool air being removed.
This little system is completely independent of my central heating system.
It works. But like all things woodstove related, it takes a bit of patience. There's no face-blistering blast of hot air through the master bedroom door. Rick
To make sure we're on the same terminology page, when I say "supply", I mean a register that delivers air to the space (blows a sheet of paper away when the fan's running), and when I say "return", I mean a register from which the system fan takes a suction (sheet of paper sticks to it when the fan's running).
My thinking in this was that if I take cool air from floor level in the remote room corners, and send it out to just behind the stove, then warmer, higher air will find its way in to replace the cool air being removed.
This little system is completely independent of my central heating system.
It works. But like all things woodstove related, it takes a bit of patience. There's no face-blistering blast of hot air through the master bedroom door. Rick
Fossil has the right idea. Take the cold return air from the cold part of the house and blow it towards the stove. This is what I do with fans down my hallway. It works great.
SlyFerret
Minister of Fire
BeGreen said:
The inspector didn't say anything. The thermostat is less than 8 feet away from the stove as well. When the stove is running, the furnace definitely isn't. Once I determined that running the fan didn't do me any good, I don't even have that running when the stove is going.
-SF
Perhaps a little OT, but I think the answer depends on the details of your HVAC install. Ask the guy what R-value duct he is going to use, many use the cheapo R-4. Upgrade to the R-8 or higher to reduce duct losses. This is a pretty cheap upgrade to your efficiency, and you might get some useful heat distribution in winter that way. When I put my system to circ, I can do 30 or 10% of nominal air flow rate (so I don't blow a lot of kWh circulating air). I used to have a major problem with unbalanced temps in my (one heating zone) house, and running my circ (for a large portion of the day) makes a big improvement. Electric usage for 30% circ is probably only ~10% of full speed.
In summary, I hear a lot of folks dissing the use of HVAC air handlers for heat distribution, but as an engineer I have to say that it must depend on the details. If you are using 100% airflow on your central system to blow air through R-4 ducts in unconditioned space, well yeah, might not be worth the electric bill. IF your air handler has a low flow circ mode (as many newer systems do), and well insulated ducting, then I would come to the opposite conclusion.
Of course, you need the BTUs to make this work--if you are just space heating now, distribution will make you unhappy.
In summary, I hear a lot of folks dissing the use of HVAC air handlers for heat distribution, but as an engineer I have to say that it must depend on the details. If you are using 100% airflow on your central system to blow air through R-4 ducts in unconditioned space, well yeah, might not be worth the electric bill. IF your air handler has a low flow circ mode (as many newer systems do), and well insulated ducting, then I would come to the opposite conclusion.
Of course, you need the BTUs to make this work--if you are just space heating now, distribution will make you unhappy.
An engineered system which fits your set-up certainly should produce results, even if not highly noticeable. Fossil`s approach isn`t dependant on BTU`s or heat loss through ducting, but encourages migration of air, and supplys a cool air flow into the stoves room to help equalize temps. I would like to know more about the type fan utilized and its location in proximity to the outlet?
ml said:
It's a Fantech FG series in-line fan, with an upstream filter box. It's in the crawl space beneath the floor, right where the manhole is, so I can change the filter without having to crawl around down there. It's controlled by a wall-mounted variable speed switch. There's a run of about 40' of duct from the remote corner of the MBR to the fan, then a run of about 25' from the fan to the register behind the stove. The other two rooms it can take a suction from are my office and a guest room, both of which are closer to the fan than the MBR, and tied into the same suction side ductwork. I think the ducts are 6", and I know they have some insulation, but in this particular application, that's really not so critical, as I'm moving cool air to the heat source rather than trying to move warm air to the cool places. I generally keep the floor registers closed in those other two rooms, so the system typically is serving just the MBR. I'd go down and get the complete fan model number for you, but if I open that hatch right now, one (or both) of my cats is gonna jump down into the crawl space, and I don't really want to deal with that. Rick
Thank you all for the input. I think I will save myself the $$ as well as the disapointment if the system doesn't work well distributing the heat. The low fan at the far end of the house sounds like a good idea to me.
Thanks again fossil :cheese: I`ve visited Fantec, when considering a system similiar to yours, and yes the Model # would help me to decide on the CFM needed, when comparing my footage in relation to yours described above. (Great Info) Whenever you got time and can corral the cats. Thanks again for your time with the Forum!
New 2 Wood said:
This is the way I would go to start with. If there is line of sight to the living room, this method can be surprisingly effective. It's cheap and allows experimenting with multiple locations.
I've done something similar to what Fossil has done. I'm using a cool air return to pull warm air through the house (see quick illustration below).
My stove is in the (finished) basement, in its own fairly small room. Distributing the heat to the 1st floor is an issue, so I force the warm air where I want it to go by using a cold air return with a good size fan installed in the return vent. The warm air is forced out of the stove room, up the stairs, through the 1st floor, and the cold air is returned back into the stove room in the basement.
My layout is different than yours, but the idea and concept of how to move the warm air to where it's wanted and needed is the same.
My stove is in the (finished) basement, in its own fairly small room. Distributing the heat to the 1st floor is an issue, so I force the warm air where I want it to go by using a cold air return with a good size fan installed in the return vent. The warm air is forced out of the stove room, up the stairs, through the 1st floor, and the cold air is returned back into the stove room in the basement.
My layout is different than yours, but the idea and concept of how to move the warm air to where it's wanted and needed is the same.
I have a similar setup - long, rambling ranch, stove is at one end, bedrooms at the other. My setup: 350-400CFM blower on the stove to make a moderate amount of really warm air. (Too small of a blower and you get a small amount of very hot air, much bigger and the blower is just too noisy.) A 10" fan sits on the mantle, set on medium high and elevated slightly towards the ceiling. This helps get the air currents moving across the ceiling and in the right direction. On the very coldest days, I put a small 5" muffin fan on the ceiling in the hallway about 1/2 way to the back of the house. This keeps thing pretty moderated throughout the house.
A few tips: Shut off any ceiling fans. They disrupt the "river of air" flowing across the ceiling. You want it to flow out to the furthest rooms, cool and come back, not be circulated in one room. You can also do a similar set-up with fans pointing toward the stove on the floor, but I've never liked the cool blast of air when walking by them. The ceiling method moves hot air and is mainly above your head, so you don't feel the concentrated draft and if by chance you do, it's warm air. Also, keep a good path open on the floor. One time I sat a large box just at the point where my kitchen counter narrows down toward the wall. This made a "cool air dam" about 3' high...the back rooms started getting cool. I moved the box and could immediately feel the rush of air as circulation was restored, then the rooms warmed back up.
A few tips: Shut off any ceiling fans. They disrupt the "river of air" flowing across the ceiling. You want it to flow out to the furthest rooms, cool and come back, not be circulated in one room. You can also do a similar set-up with fans pointing toward the stove on the floor, but I've never liked the cool blast of air when walking by them. The ceiling method moves hot air and is mainly above your head, so you don't feel the concentrated draft and if by chance you do, it's warm air. Also, keep a good path open on the floor. One time I sat a large box just at the point where my kitchen counter narrows down toward the wall. This made a "cool air dam" about 3' high...the back rooms started getting cool. I moved the box and could immediately feel the rush of air as circulation was restored, then the rooms warmed back up.
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