Forced draft owb

[2012outdoorsman]

Been reading for a little while now and decided to post as I've never come across an answer to my question.

I have a heatmor owb with a single blower to heat my house (2200sq ft not including basement). I bought my house from my fil who put the owb in about 10 years ago. His new house he bought a central owb due to the natural draft sign and thinking it would burn less. We'll all in all he burns roughly 40% less than I do and cam easily get 24hr burn. There is no way I can burn that little wood and was wondering if down sizing the blower would help. The wood burning often turns into a funnel shape and burns much quicker when next to the blower. It also can have flames seen at the end of the chimney as it's only 6"long. I've looked into the blower size and have thought about just buying one 50% smaller but was wondering if anyone gave it a try. Even a variable one would be nice.

He does have better insulation and all my house is only from 1986 wit decent insulation. I did the blown in insulation for the second story this summer and brought it from an r30 to roughly r50-60. When redoing the upstairs this summer I pulled up all plywood floor and put r30 unfaced in which may help too.

Thanks!

 

[hupte]

first off, welcome to AS!!!!

I think the difference is really the insulation in the house. I have heard "claims" that the natural draft boilers are more efficient but I've never really seen a side by side comparison. I believe the forced air blowers have a quicker recovery time. due to the fact that they really get the fire roaring in a shorter amount of time. I would like to get a bigger blower for mine to have even faster recovery.

you could tape off part of your blower intake that would cut down on your air flow. but I would think it would just make the blower run longer and your wood consumption would remain the same. but thats just a guess.

good luck in whatever you decide and please don't hesitate to post results and pics. everyone here enjoys a good experiment and a few pics.

 

[cantoo]

Been thinking the same thing but with a little twist. I have already tried the tape thing on the blower hole on my Pacific Western. Too difficult to tell if it makes any difference though.
What I want to try is to shut down the fan sooner but keep the draft door open. Haven't spent the time to figure out how to do that though. My thinking is there is too much air blowing into the fire when it gets going, I think if the fan were shut down and the flap stay open it would still draft naturally and slow the burn down but still put out enough heat.

 

[2012outdoorsman]

I may have once left the door for the auger clean out open once essentially letting it become a natural draft. While it maintained temp over this time ())about 2 hours) I had no control if it overheated. Luckily it was cold and maintained around 175°. I would never have done this on purpose but I got distracted.

I personally just don't see how the tape thing will do anything. Please correct me if I'm wrong in any assumption as to why I don't feel it's worth trying. The blower puts out say 75cfm. It's has one speed and is always going to try to put out 75cfm. If the whole is made smaller the velocity would increase to put the same amount of air through a smaller hole. The same for if the whole was made larget the velocity would decrease as it's still supplying the same amount of air. The smaller whole in my mind make the blower work harder and may burn it up quicker.

I understand the fact that if you bring it up to temperature faster it will shut down faster thus using less wood. However, if the fire gets to large and fast, how much of that is just going right out the chimney and nother heating the water.

I've looked at the smoke coming out the chimney and compared it to my fil central and mine is most deffinetly faster.

To give a little more background, I'm heating only one floor of my house with it. I just redid the upstairs and that has electric heat as they never ran heat up there. I've left it so I can easily add it but currently just don't use it yet. I will be soon as my son is 3 months and by next winter he'll be up there. My fil is heating 2 floors for a total of 3200sq ft one floor being 10foot ceiling height. He also has r50 in foundation compared to my block foundation which is a huge difference. I know this is an apples to oranges comparison but I just feel that I could be doing better.

 

[msmith]

Don't know about the Heatmore, but I had a Taylor at our old house and now have a CB Classic 6048. My Taylor had an adjustable cover on the intake of the blower. I didn't see much difference, if any, with any adjustment of it. The thing I did not like about the forced draft models is; the do get the temp up quick with the blower, but once it comes up to temp and the blower kicks off, you still have a small amount of natural draft. In warmer weather, I would notice that my Taylor would boil and steam would be blowing out the vent.

I do think that I burn less wood with the CB than the Taylor. The house I have now is about 400 square feet larger and is a old and not quite as efficiently insulated as my old one and I burn maybe a cord or two more than I did at the other house with the T. As far as longer burn times...don't know about the HM, but my CB has a larger fire box than my T, so 24 hour burns, even in the coldest weather are norm now. With the T I tended it every 12 hours and in sub zero temps, I hit it every morning, after work, and a freshen up right before bed.

 

[motoman3b]

I know with my blower like msmith I did get some natural draft before i rigged up a backdraft valve on my blower intake, this sealed it off better but opens when the blower kicks on it really helped my wood consumption the smoke barely comes out of the chimney when its idling now before there was some degree of fire going and uneffiecent at that, all I did was silicone the valve on the outside of my blower and had to add a bolt to the top of the flap to keep it closed cause the natural draft would still wanna open it but did this mod abour four years ago and its worked great

 

[03HD2500]

I have forced air and I have a plate attached to the air intake and I can adjust how much air I let in and I have it set around 1/2 way open and seems to be working pretty good this way for me.

 

[jcl]

I notice less smoke with blower. Out the stack which I like.

 

[greendohn]

I've read somewhere where a guy was playing with a 2nd ?snap disc/aquastat? set up one for the blower and the other for the blower door. Keeping both of the units to open at low set temp like normal operation but having the 2nd set up to shut down the blower after a couple/few degrees of increased water temp and leaving the blower door open until the water temps achieved the upper set point. The idea was to have the blower fan get the fire started back to life, then the stove actually going to natural draft until the desired set temp is achieved.
Not sure where I read about it, it wasn't where the cool kids hang out with the *****, it might of been where the firewood hoarders hang out.