Trying to move air through the house, Fail !!! with fans

[Doug Doty]

I just started with my pellet stove this fall but I know a little about HVAC or I thought I knew something. I put it in a sun room that was built onto the end of our 1700 sq.' townhouse style two story home just to heat the sunroom alone and not use the baseboard heaters in a 90% glass room. Immediately and to our amazement the stove showed signs of maybe being able to heat the whole house so I went about mastering the art of movement of heat from one room to another as I know all about that. Yea right. I tried it all, ceiling fan down, then up, floor fans blowing heat to the next room, blowing into the hot room to blow the heat out, use the Hvac system blower, doorway top corner fans. NONE OF IT WORKS, PERIOD. Some may think they are being successful with this or that, but i really doubt it if they factually test the results. Every fan or blower I set up made it colder where it was blowing or had no effect. I have a good bit of high quality test equipment and can check wet bulb temp, dry bulb temp, humidity combustion analysis, I have anemometers, manometers, Psychrometer that can test and calculate cfm through doorways or ducts, you name it, and a new pile of crude thermometers from Lowes that were strewn about the house. I am anal when it comes to data to a serious fault but in the winter I enjoy these kind of indoor challenges. Some here have had their chuckles at my silliness trying to apply science and data to pellet stoves but It all worked to factually prove through the use of data that nothing works.

What I found is simple....and at least is applicable in my house and I doubt if it varies much in anyone else's when it comes to moving hot air around coming off a stove or out of a hot room. blowing it around seems like it should in all logic work but it don't. Our furnaces only do it through duct work because they start out so hot hot and the flow is confined inside the ducts, they do cool the hot air a lot and are very inefficient and it is why the new ductless split systems are replacing ducted heating and air conditioning all over the world when applicable. Here is what I have learned in countless hours trying to move hot air through my house with fans and such.

#1) When you try to move heat with a fan or blower the acceleration of the air through the device cools it as fast as you move it and you gain nothing but a drafty feeling house and it will actually feel cooler within the throw area of the blower or fan. Move it slow (not enough benefit) to measure, Move it fast or faster (cools too much in process and no benefit) other than cooling.

#2) If you want the adjacent room to be warmer, there is one choice, heat up the room with the stove more and the adjacent room will increase. Heat seeks out cold and when you create a temperature differential it will move efficiently on it's own.

#3) The only value a ceiling fan has in the stove room is, to cool the stove room down, if it has been heated up a little extra to move heat into adjacent rooms and the stove room has gotten too hot it can make it feel a bit cooler with no negative effect on the adjacent rooms temperature objective.

#4) If I want my upstairs bedrooms to be 65 and I do, I elevate the stove room until they get to 65 and if I am hot sitting here I turn my ceiling fan on low and make it a bit drafty here in the stove room so i am comfortable even though the thermometer beside me says 79 or 80. For some reason this does not effect the stove rooms ability to push heat out into the adjacent rooms. I can have the fan on in here to make it comfortable and it does not change the adjacent room temp or effect the heat moving through it to the upstairs.

#5) It goes without saying but worth saying again, air leaks can consume a lot of your heat that would otherwise be filling your stove room and then spilling over into other parts of the house. Even just last night I added some more sponge weather seals to the windows I was finding drafty in the stove room and I got hotter sitting at my desk due to stopping a draft under my chair so I am wasting less heat. Search out you leaks on the coldest nights as they are much easier to detect and find smaller leaks in single digit temps that is the 20's or 30's

#6) Keeping my stove room temperature consistent really helps with maintaining the temperatures stable at the farthest points and room from the stove. If I shut down the stove for 10 minutes for a minor cleaning in cold weather, i can loose 5 degrees in the stove room and maybe 2-3 degrees in the upstairs. The stove room will come back up very quickly but the upstairs takes quite a while to come back up to where it had gotten up to. I have learned to get in and out quickly.

This represents about 2 months of experiments by me being bound and determined to move heat by mechanical means and I could only cool rooms down with fans or blowers but never raise their temperature as observed through actual testing. Your actual mileage may vary.

For the people that are trying to blow heat into other rooms, and questioning it's success, just try heating up the stove room a bit more and then if needed try a small amount of fan in that room to change the feel if it gets a bit hot. I often use the ceiling fan in here on low for that reason, up or down makes no difference.

This was all fun in process but frustrating and yet amazing at times. in the end we use only the ceiling fan in the stove room a little and are successfully heating a 1920 sq.' two story townhouse from an all glass sunroom/stove-room that was added on to one end several years ago. All of our heat has to move through the old outside door that now is an inside door into this add on room and find it's way through the house through convection and it is working quite well.

 

[Doug Doty]

Wow that was kinda long but you may find it interesting.

 

[Pellet-King]

My old 1952 cape 1500sqft see's temps up 10 degree's colder next room over, I have to 2 entry ways from the living room to the kitchen/dining room most capes have only a hall into the other side of house, im sure my wall's have zero nsulation, my windows are 6 yr's old, most of the heat goes upstairs where's there's 2 small bedrooms and a large bathroom dormer, why for the life of my they didn't build a full dormer for probably back then $100? more in lumber..

 

[john193]

Doug, couldn't agree with you enough. I typically cringe when people suggest using the hvac system to move air around. Duct work is the single most inefficient system in a house. Infact the rest of the world has been using ductless heating and cooling for decades already.

People would be surprised how many of their ducts are on exterior uninsulated walls and generally not properly sealed.

IMO running your hvac blower with a pellet stove defeats the sole reason of buying one, efficiency.

 

[Hi-Standard]

My house has three levels, about 600 sq/ft each. Pellet stove is in the basement and all of the convection blower heat is ducted(insulated 4" dryer vent) up to the main floor dining room. Radiant heat from the stove heats the basement, ducting heats the main floor. I use a small floor fan on low to blow the heat across the dining room floor grate to the hallway side and a pedestal fan on medium and pointing down towards the floor to blow the heat out into the living room. Ceiling fan in the dining room on summer mode(blowing down) on low to keep the heat low to the floor. Outside temp yesterday was -6C and the inside temp in the dining room was between 25 and 26C while the living room was at 24C all day. All I'm using for a stove is a little Timber Ridge 55-SHP10. Had the heat setting on 4 and the blower on 7 all day. Burning Canawick hardwood pellets. Main thing I found is not to turn the fans up too high, this just seems to create a cool draft. I would like to see a little more heat reach the upstairs bedrooms, but they are liveable. 18-19C.

 

[Drew65]

It took me a few try's to find the right spots and the right fan but I have great luck doing it. I have a small quiet fan on the floor on low pointed back down the hall to the stove room. It gives me a 4 degree bump in temp in my bedroom.

 

[CladMaster]

Yes, that's the trick, slow air movement and not fast.

 

[alternativeheat]

What really works in my house is a north wind outdoors. The south side being the cooler part of the house. Anything NNE, N, NNW. Prevailing wind though is NW or WNW and that is not as effective. In the summer it's SW. Anyway I have gotten so I don't even have to look at wind direction outside, I can tell it's blowing N"ish" because I can feel the heat from my stove on my face when sitting in the south side of the house someplace, anyplace. It's the most even heat from my stove all winter long.. I don't so much attribute this to draftiness ( wind blowing through the house) as negative pressure on the south side of the house and positive on the north.. My most sealed side is the north and least sealed side is the south. My house is like a weather vane.

I get some limited results with fans. I have found the best approach to fans is blowing up and turned on very low. You just want to give a little push to the warm air at the ceiling. .

 

[DBCOOPER]

I just started with my pellet stove this fall but I know a little about HVAC or I thought

Our furnaces only do it through duct work because they start out so hot hot and the flow is confined inside the ducts, they do cool the hot air a lot and are very inefficient and it is why the new ductless split systems are replacing ducted heating and air conditioning all over the world when applicable.

#1) When you try to move heat with a fan or blower the acceleration of the air through the device cools it as fast as you move it

This represents about 2 months of experiments by me being bound and determined to move heat by mechanical means and I could only cool rooms down .

Congratulations, looks like your studies have made air conditioning obsolete.

 

[SidecarFlip]

Wow that was kinda long but you may find it interesting.

I find it kind of boring in as much as many posts and threads ago I told you to get a t'stat that would cycle your central furnace blower for a set amount of time every 15 minutes or so. Obviously, you didn't listen. Oh well.

Have fun.

 

[millerized]

Realizing that heat rises, and cool drops...if you want heat into a room, you need to move the cold air out. Blowing air into a cold room from the floor only moves cold air. Turn the fan around if it's on the floor. Blow the cold air into the room with the heater, warm air moves out over the fan into the room you want heated.
Just my experience working in a poorly ventilated shop with no AC in the summer, and little heat in the winter.

 

[SKOAL MAN]

I am fortunate enough to have an air circulation mode on my furnace. It comes on intermittently at very low speed, during the day to circulate and clean the air. I agree that a high speed fan defeats the purpose, you are better off blowing cold air at a hot stove than blowing warm air into a cold room.

 

[SmokeyTheBear]

Here is my solution:

The upper portion of the the air distribution system




The lower portion.





It is powered by the stoves convection blower system which is set to follow the heat range.

Cold air gets sucked into the stove below where the hot air is pushed out of the heat exchanger, the warm air rises and exits the stove room still rising. It continues to rise until it is blocked by the ceiling and spread out into the great room and such.

The cold air from upstairs falls down the stairs into the stove room.

See Ma no extra fans needed.

 

[jp99]

I find it kind of boring in as much as many posts and threads ago I told you to get a t'stat that would cycle your central furnace blower for a set amount of time every 15 minutes or so. Obviously, you didn't listen. Oh well.

I agree with using the central blower. I have an old heating system in my home (55 year old NG furnace, forced hot air circulation). The best investment I made is having it wired so the blower can turn on independently and building my own digital timer relay box to control that. Nothing like being able to set the cycle period and % on time digitally

The primary change I needed to make is setting the vents properly on the main floor and the basement. My stove (PC45) is on my ranch's first floor. So I dump cool air into main floor room (where the stove is located) and the basement, and draw return air mostly from the rest of the house. The duct air is warmer than the basement (helps heat it), and is cooler than the main stove room so that air is heated. Meanwhile the central air system is drawing off the cooler rooms in the end of the house far from the PC45. After a few years of experimenting this proved the best air mixing arrangement for my home.

My PC45 runs in stove mode - fixed ESP exhaust temperature - and not in the temperature probe/mode. I run it just enough so the main furnace fires up occasionally in cold weather (under 20) and almost never above 35. It still puts heat in some areas better than my PC45.

I'll echo using fans on slow speed - I use a small Vornado fan up high (on a bookcase) in the stove's room to push hot air gently down the hallway to the bedrooms. The hallway is like a large duct, as you can feel the gentle air movement (hot air up high, cool air coming from the bedrooms down low). Only disadvantage is having to keep the bedroom doors open for heating purposes. That's the only fan I use. The coldest bedroom is 3 to 6 degrees cooler than the main stove room, depending on outdoor temperatures.

Main blowers and small fans are fine to use - move heat with small fans on slow speed, and mix your house with the main blower.

Some here have had their chuckles at my silliness trying to apply science and data to pellet stoves but It all worked to factually prove through the use of data that nothing works.

Well, it can work. Your instance may be a more difficult setup, and may not work as well as other blower/ducted homes, but to say "nothing works" is a bit extreme.

 

[Doug Doty]

I find it kind of boring in as much as many posts and threads ago I told you to get a t'stat that would cycle your central furnace blower for a set amount of time every 15 minutes or so. Obviously, you didn't listen. Oh well.

Have fun.

I'm usually a pretty good listener but don't recall this one. I'll be damn, the magic bullet was offered and I missed it. Just my luck. Oh well. I have a dumb thermostat and want a more sophisticated one that can do things like that. I'll try to find one, try it and report back here. Based on all the above testing I have done, I'll say that I am not hopeful for it to work in my particular situation but I have come across a lot of thing that worked different than I thought.

 

[Doug Doty]

Doug, couldn't agree with you enough. I typically cringe when people suggest using the hvac system to move air around. Duct work is the single most inefficient system in a house. Infact the rest of the world has been using ductless heating and cooling for decades already.

People would be surprised how many of their ducts are on exterior uninsulated walls and generally not properly sealed.

IMO running your hvac blower with a pellet stove defeats the sole reason of buying one, efficiency.

That is what I found. I have not tried pulsing the hvac blowers as side car suggested but I'm gonna try. He does not offer useless info so always worth listening to even if he scolds me for missing something. Easy to simulate manually. and if it gives any positive sign at all I'll invest in a new stat right away. It will have value other times of the year so It won't be a waste either way.

 

[Lake Girl]

Doug's stove set-up is situated at one end of the house. Proximity to a stairwell (like Smokey's) and centrally located seems to be the key to moving the air through both levels of the house.

Setting up the HVAC to pulse may assist but you will have to figure out how often to pulse - too frequent or not enough may prove ineffectual...

 

[Snowy Rivers]

All very very true.

The house layout can make a big difference for sure.

Years ago, we lived in a 1300 ft single level with a long hallway with a jog in it.
Our one stove (Earth pellet stove) and it was in the far end of the house in an alcove in the living room.

The warm air would travel across the ceiling and down the hall, and the cold air would race along the floor.

Amazingly, the entire house would stay quite comfy.

I too have tried using the HVAC air handler to move the heat. Nope, bad plan

The house here at the ranch is wide open and heats well with simple convection.

WE do have 3 stoves though, located throughout the house.

But depending om outside temps, one is normally enough to do the trick, except when it gets COLD


The old tried and true response about pellet stoves though holds true "They are a space heater"



If it works, keep doing it.


Snowy

 

[woodmakesheat]

My experience confirms that this is generally the case. I place a fan directly on top of my stove to direct air at a slight angle compared to the normal airflow from the stove so it will pass through a doorway toward the room that has the thermostat in it (thermostat about 12' from the stove front). The stove room also has a thermostat that is connected to the oil fired backup system. In addition, there is a return path for the fan air as main part of house is an "O" shape. I see a 1 degree difference and that's it. Stove room runs 1 degree cooler and thermostat room runs 1 degree warmer. This does save me some fuel by putting the stove in the low setting for periods of time where the stove is just barely achieving thermostat (temps below about 15 .)

 

[bogieb]

Congrats for figuring out what works at your house. My house isn't the same configuration, so your setup does not work the same for me.

Point 1: "When you try to move heat with a fan or blower the acceleration of the air through the device cools it as fast as you move it and you gain nothing but a drafty feeling house and it will actually feel cooler within the throw area of the blower or fan. Move it slow (not enough benefit) to measure, Move it fast or faster (cools too much in process and no benefit) other than cooling." Besides a quibble with moving air cools off (air is not subject to a wind chill), my living room, where the stove is, can be 85, and the hallway is 70, with the bedrooms in the 60's. Two fans at the mouth of the hallway, pointed to the bedrooms, warms the bedrooms up quite nicely. I have demonstrated this fact by turning off the fans and having the BR's cool off starting almost immediately, then turning the fans on and watching the temp rise to the 70's. Yes, I will agree the LR is warmer (anywhere from 74-80+ since I have it on a thermostat set up in the office at 72), but the bedrooms stay within a 2-3 degree range because of those fans.

Point 2: "the only value a ceiling fan has in the stove room is, to cool the stove room down, if it has been heated up a little extra to move heat into adjacent rooms and the stove room has gotten too hot it can make it feel a bit cooler with no negative effect on the adjacent rooms temperature objective." In my house, with the ceiling fan going (slowest setting), I can feel the heat coming down from the ceiling and the LR thermostat reflects that difference.

Point 3: "If you want the adjacent room to be warmer, there is one choice, heat up the room with the stove more and the adjacent room will increase. Heat seeks out cold and when you create a temperature differential it will move efficiently on it's own." Not in my house it doesn't. Heat actually seems to search out warmish areas here. When I just had my downstairs stove, I couldn't get heat to rise for love or money (and lots of holes cut in the floors, stairway door removed, and stairway wall knocked out). However, whenever the boiler kicked on (because it was 62 upstairs), warm air would rush up the stairway from the stove. And no, my house wasn't anywhere near tight, so that wasn't a hindrance to air flow. Additionally, see my answer in point #1.

I'm not saying your points are incorrect (except that wind creates colder air thing ), I'm saying that what is true for your house, is not necessarily try for someone else's house.

Once again, I am glad you figured out what works for you!

 

[GeHmTS]

Early on, I was using fans and I had a 10-12'F differential between the stove room and the adjacent room. Part of the warm air had to go through a hallway where the outside door was located. The door was drafty and you could feel it in cold weather; this is where we definitely suffered heat loss.

Well, we recently had our doors replaced with insulated doors. the differential dropped to 5-7'F differential without the use of fans. It's no longer drafty and the adjacent room is more comfortable than before.

My point is that anything you can do to improve the R value is worth it. Doors are easy and affordable and will give you a quick ROI. We were going to replace our windows too, but it's too expensive for now.

I have no HVAC, no fans, 2300 sq ft, including a sun room, and the stove is sufficient for the entire house.

 

[chken]

Thanks Doug for your scientific observations. It all makes intuitive sense when you've written it down. I haven't given it a great deal of thought as you have, but my anecdotal results seem to match. I run my five reversed ceiling fans on their lowest setting, so as not to create a draft, but to slowly help circulate the air, so that all the open areas normalize to the same temp. In my great room, I've got 26ft ceilings so it's a unique challenge, but I'm sitting here at my desk with a thermostat right next to me and it's 64 degrees, which is the same as the thermostat sitting in the kitchen about 10ft from my stove. Again, thanks for the myth busting.

 

[DneprDave]

I also use my pellet stove to heat a sunroom. Before the pellet stove, the sunroom was used as an auxiliary refrigerator during the winter. I used about 600 gallons of oil a year to heat the house. Now, I use about 250 gallons a year.

My house is single level,1700 square feet. The 40'x12' sunroom is on the view side of the house and is all glass, other than the insulated floor and roof.
The wall between the sunroom and the house is glass with three sliding glass doors.

In the winter, when the outside temperature is anywhere from the mid thirties to the low fifties, the pellet stove keeps the sunroom around 63F at it's lowest settings. I leave the sliding glass doors to the sunroom open, this augments the oil furnace which is set to 63F. I don't use any fans, just natural convection. At night, I close the sliding glass doors and set the oil furnace's thermostat to 60F, often the sunroom is warmer than the house in the morning, when I open the sliding glass doors.

I have been using almost three tons of pellets a year.

Dave

 

[Deromax]

Congratulations, looks like your studies have made air conditioning obsolete.

I was just about to say that! Moving air will make it *seem* cooler to your skin, but the actual temp or energy content hasn't changed.

So this was a long post to explain that using a space heater won't properly replace central heating. This was a generally well known concept!

 

[TimfromMA]

I tried fans of all sizes blowing every which way but my best results came from shutting them off and letting the stove do it on its own.