Adding a Blower to Jotul F 400 Castine

Okay, so all of this talk about blowers got me to do some experimenting. I love doing this stuff. So I dug up a 215 cfm Fasco blower motor that I had used for another project and a rheostat. I wired it all up and did some testing. (FYI, Jotul does not make an oem blower for the Castine, I called 2 dealers to verify).

So I can tell you that the blower definitely cools down the stove, lol. I fired up the stove and got it good and hot and then filled the firebox with a full load of wood. With wide open air (and bear in mind I am using the larger opening EUR plate) I easily got the stove up to 500 degrees. Then I fired up the blower and as the stove crept up to 600 degrees, I kept increasing the fan speed until I finally maxed out at 2,800 rpm. I couldn't get the stove to climb above 600 degrees with wide open air. Amazing. Without the fan I would have easily hit 700 degrees and kept climbing to over-fire territory.

Now, bear in mind that this is a pretty big blower and at max speed it is fairly loud, but it can move some air. I got the whole upstairs of the house up to 71 degrees on one load. Normally I wouldn't hit those temps until the second load. Interesting.

I tried several orientations of the fan. What seems to work best is to pull air in from the bottom and force it up the back of my hearth and then out around the top of the stove. Does this make sense? I also tried pushing from left to right and also putting the fan in front of the stove. Here are a couple pics:

So I am very happy with the testing done so far with the blower positioned at the bottom rear of my hearth. It basically pulls cold air in from under the stove and then shoots it out the top of the blower behind the stove, up the back wall, and then the hot air flows out of my open hearth out to the sides. The amount of additional heat transfer into the room is incredible and I literally just threw the blower in there with no shrouds or anything. I have attached an airflow diagram. I just ordered up a smaller Rotom blower rated for 130 cfm at 1,200 rpm because I think the one I currently have is over-kill.

Oh yeah, one final observation:

I was actually able to get the temperature in my hallway further away from my stove to 72 degrees while the temperature in the main living room where the stove is located was at 71 degrees. I have never seen this occur. The temps have always been warmer in the living room. I suspect this is due to the massive increase (prob too much) in airflow.

The goal now is to try to refine the design into something that is as quiet and invisible as possible while still circulating the air and transfering the heat into the room. I think 100 cfm is about all it will take so I have a little head room with the new fan. I also went for a slower 1,200 rpm model to reduce the air noise further. I should be able to fine tune the optimal setting w/ the rheostat. I am also going to fabricate a simple mounting bracket and shroud out of sheet and spray it all black. I have another idea to elavate the fan a bit in the rear and literally mount it to the rear wall of the hearth. This would make it virtually invisible from the front, other than the power cord.

Oh yeah, the side to side airflow pattern worked quite well at transfering the heat as well. I just didn't like that the fan needed to be mounted vertical to the side of the stove/hearth.

Frostbit said:

Nice test!

I would have thought you might have seen some different burn characteristics when the blower is running, due to the fact that you now have a suction effect across the bottom of the stove, which is right where the stove's air intake hole is.

Click to expand...

Good point and you are correct that there is like a 3" round intake at the bottom rear of the stove. I was very careful to be sure the fan was behind this to minimize any robbing. I think the slower fan will help in this regard. 200 cfm was way to much. This may have been a contributing factor to why I was able to run at 600 degrees with the air wide open without any running away of the stove. I experimented with different fan speeds and tried to look inside and see if the fire was burning any different and I couldn't see anything perceptible.

I did notice that if I turned the fan off, the stove temp started to climb right away. As soon as I turned the fan back on and cranked it up, I could literally cool the stove down - particularly if the load had started to burn down and was no longer burning hotter.

CSH carries Rotom blowers (among others). Lots of selection for reasonable prices:

https://www.cshincorporated.com/

Rotom blowers:

http://www.alltemp.ca/prod_index.htm

Update:

Okay it is 8°F outside. I have the house at 68-70 degrees depending where you measure the temp. I have found that I can literally cram the 1.75 cu. ft. firebox of the Castine with wood to the baffles and run at 100% EUR air. If I run the fan at max speed I can keep the stove top temp to 600-650 degrees. There is no glowing and no signs of over-firing anywhere on the stove, BUT the secondary burn that I am getting is incredible.

Here I am cruising at 650 °F with stove air at 100% and fan at about 90% and the reburn is awesome:

Update:

Okay this is the latest Rotom RB84 blower I am using. It is 130 cfm 1,250 rpm vs. the 215 cfm 2,800 rpm Fasco I was using for my first round of testing. You can see it is smaller yet the wheel is a larger 2.6" diameter. This keeps the noise and vibration very low - a marked improvement. Sure enough, this is more than enough blower to get the air circulating out of my old fireplace and into the living room. For $85, you can't go wrong. I'll prob work on the housing this weekend to finish off the install.

The blower has been working real good. It does a great job of getting the hot air out of my old fireplace and into the living room. I can't quite run at full open air with the blower at 100% as the new blower is smaller, but I can run that way for maybe 1 hour before I hit 650 degrees. This is the method I employ to heat up the house quickly. Since I only burn on weekends and evenings this is a perfect match.

My basic method has been to load the firebox full and once the temp gets to 400 I engage the blower. I have been backing off the primary air as well as the blower speed earlier to try to keep the temps in the efficient 500-600 range. Based on my wood consumption so far this year, this is working remarkably well. We have noticed that the blower has smoothed out the temp spikes considerably and you can set it and forget it more easily. The preferrred setting is at about 50% as the blower becomes virtually silent (sounds like a laptop fan) and it still circulates enough air. I match that with 25-50% primary air depending on the wood load and stage of the burn.

It's not just with this stove. It seems the be the same thing when a blower is added to any stove. You are just increasing the heat transfer by blowing more air across the hot surfaces of the stove increasing convection and then throwing the heat into the room. The only problem with the Castine is that there is no oem option so you have to put together your own fan and shroud setup.

Yes a Rotom RB84. It is 130 cfm @ 1,250 rpm.

I haven't yet used it this year...still waiting for the cold weather.