Building a wood boiler!!

[adamsjosh1977]

I'm building a outdoor wood boiler, I have a couple questions, I want to run natural draft and a blower when it's only needed. My thinking. Damper opens at 155, closes at 180. Blower kicks on at 160 off at 170. I'm thinking of running dual aquastats. I would greatly appreciate any help or advice.

 

[maplegrovetom]

I'm building a outdoor wood boiler, I have a couple questions, I want to run natural draft and a blower when it's only needed. My thinking. Damper opens at 155, closes at 180. Blower kicks on at 160 off at 170. I'm thinking of running dual aquastats. I would greatly appreciate any help or advice.[

I've built several. It will take 2 aquastats to do what you're looking for, but what I've found is less is more, so don't over complicate things with what you're attempting to do.
Go with the forced air induction and just one aquastat. Mount the fan so a solenoid with a block-off plate covers the blower air inlet when the aquastat is off or power goes out as a safety measure. If you're looking at the aquastat controlled natural draft as an electricity saving feature, it won't save you $5.00 per month. Burning wood already saves you a huge amount of money. Put your chimney low in the firebox, and design it with as few welds as possible. Good luck

 

[absrio]

also get a good plan and stick to it. worst thing is welding then cutting it off the next day. I just upped my blower from 50 to 100 cfm this winter. and I couldn't believe it but I'm burning less wood and making much less smoke. the small blower used to run for 4 hrs and shut off for 20 min. the new one runs for 20 min and stays off for an hour or more. my neighbor changed his blower to a bigger one and he said he was burning less wood. I didnt believe him until I did the same thing with the same results. I wouldn't believe it unless I saw it. this is the new blower I'm using.
http://www.ebay.com/itm/391092294190?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 

[mohick]

Why double everything nothing at all wrong with blower draft Use the K I S S system Keep It Simple, you are not Stupid or you wouldnt be building it!!

 

[H-Ranch]

I'm building a outdoor wood boiler, I have a couple questions, I want to run natural draft and a blower when it's only needed. My thinking. Damper opens at 155, closes at 180. Blower kicks on at 160 off at 170. I'm thinking of running dual aquastats. I would greatly appreciate any help or advice.

I have been wanting to run mine similar to what you describe - right now I am running the same size fan as absrio shows above. I would consider a separate air inlet for natural draft vs. forced draft (might be tricky to block the natural draft inlet at the same time when the fan runs.) I have run mine by just opening the block-off plate without turning the fan on and it seems that the fan bearings get gummed up with creosote. If you do use 2 aquastats that makes for a built in spare that you can quickly rewire to keep you in operation if one goes bad. I don't recall if there are any aquastats that allow for 2 circuits with different settings. If you find that it doesn't work then it's easy to change back to just forced draft.

Get the best insulated PEX you can because that's the hardest part to do over. Locate the pump in the basement. Make the door to the OWB higher than you think you need. Do a search for other tips and tricks on home built units. And show pictures!!

 

[absrio]

also don't skimp on quality. you can either build it to last 20-30 years, or build it as cheap as you can and it will last 5-10. I like the round firebox design myself. but whatever you go with make sure you double weld it. you'll need a fresh air supply to do the inner welding inside the firebox. but once its up and lit its all worth it. 2 years from now you won't think of the money you saved by cutting corners, but you will think of the quality and longevity you lost.

 

[jgoodhart]

Natural draft seams like a step backwards, kind of like a carb to fuel injection. I run 2 blowers on mine one for under and one for over top of the fire. I start both blowers and open bottom damper and when the flue exhaust reaches 130 I open the top damper, then things heat up.

 

[dumbarky]

Does the blower, over the top of the fire, help with secondary burn?

 

[NSMaple1]

You will get very little if any secondary burn happening in a water jacketed boiler no matter what you do with air.

Having a liquid cooled firebox kinda puts the damper on that.

 

[jgoodhart]

It don't burn like those fancy stoves do but it does ok.

 

[adamsjosh1977]

I'm getting close now, life is crazy busy

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[adamsjosh1977]

I'm getting close now, life is crazy busy

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[adamsjosh1977]

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Any questions, or concerns would be greatly appreciated

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[adamsjosh1977]

Any questions, or concerns would be greatly appreciated

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Sorry learning how to send the pics here

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[adamsjosh1977]

Sorry learning how to send the pics here

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?

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[adamsjosh1977]

also don't skimp on quality. you can either build it to last 20-30 years, or build it as cheap as you can and it will last 5-10. I like the round firebox design myself. but whatever you go with make sure you double weld it. you'll need a fresh air supply to do the inner welding inside the firebox. but once its up and lit its all worth it. 2 years from now you won't think of the money you saved by cutting corners, but you will think of the quality and longevity you lost.

No I did not skimp on quality, I'm kinda a perfectionist. The fire box, door, and chimney is 1/4 and the water surround is .120 so a hair under a 1/8

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[adamsjosh1977]

Natural draft seams like a step backwards, kind of like a carb to fuel injection. I run 2 blowers on mine one for under and one for over top of the fire. I start both blowers and open bottom damper and when the flue exhaust reaches 130 I open the top damper, then things heat up.

No I did it as a natural draft until the temps get too low, then the blower kicks on. The damper closes at 180 to prevent boil overs and opens back up at 170. Blower kicks on at 155, shuts off at 170

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[adamsjosh1977]

Firebox is 10"x20"x30". Water jacket is 3'×3'×4'deep. Holds close to 125 gallons

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[dave_dj1]

It will be interesting to see how it performs with such a small (narrow) firebox. What size building are you going to heat with it?
Make sure mice can't get into that insulation.
Years ago I had a wood add on unit that had a aquastat controlled draft under the grate, I found that when the draft opened it took most of the wood to bring the temps back up and the fire just wouldn't last. I unhooked the aquastat and ran the draft manually as the outdoor temps commanded, I never had a problem with it lasting overnight after that.
Any pictures of the chimney inside the fire box? How much do you figure you have into it?
Good luck with it, I hope it performs as expected.
Dave

 

[adamsjosh1977]

It will be interesting to see how it performs with such a small (narrow) firebox. What size building are you going to heat with it?
Make sure mice can't get into that insulation.
Years ago I had a wood add on unit that had a aquastat controlled draft under the grate, I found that when the draft opened it took most of the wood to bring the temps back up and the fire just wouldn't last. I unhooked the aquastat and ran the draft manually as the outdoor temps commanded, I never had a problem with it lasting overnight after that.
Any pictures of the chimney inside the fire box? How much do you figure you have into it?
Good luck with it, I hope it performs as expected.
Dave

Yeah I know, but I had a piece of 10x10 steel tubing laying around so I just cut the seam side off and rewelded the two together. The way it sits I may have 500 in it right now

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