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[Acetylene420]

I wish I had found this great forum before starting my build but I didn't.

I've attached pics of the firebox and water jacket. Due to the vast amount of knowledge and experience many of you have, I'm sure I've done a few things wrong. This is my first build and I'm doing it from my own ideas and without a set of plans. Please go easy on me. I'm very interested in any and all feedback and criticism regarding what I've built so far. Obviously, with the work, steel and money already committed to the boiler build, radical "cut it apart and start over" suggestions aren't realistic.

I've never owned, used or seen an OWB before so I'm basically winging it. Like I said, I truly wish I had found this site before I started. But anyway...

The firebox is 1/4" hot rolled plate. It's 28" long, 24" wide and 32" tall. I've installed a 3 1/2" schedule 40 pipe under the rack for the blower to inject air under the grate. The grate is 1" round bar. My plan is to run 6" schedule 40 pipe out of the top of the firebox as the exhaust. From what I've seen on this site, I'm thinking the pipe should extend 12" or so down into the box.

The water jacket is 3/16 hot rolled plate. It is 36" wide, 48" tall and 38" long or deep looking at it from the front. I've calculated the water capacity to be 196 gallons once the firebox is installed.

I have installed a 1/2" steel bung in the bottom plate for a drain hosebib.

My questions are: 

1: is it worth the extra steel and time to weld 1/4"x2" flat bar, on edge, on the outside of the fire box? The thinking being it will act as a heat sink allowing the water to come in contact with more surface area. Similar to the "fins" on an air cooled engine. I also think it may "swirl" or mix the water around the box better. I may be way off on this thinking but figured I throw it out there.

2: based on the sizes of the fire box and water jacket, how far off the bottom should the box be? I plan on installing 1" bungs for take off and return lines. I will be pulling from the bottom (of the back water jacket plate) and returning into the top. I've planned to extend 1" copper pipe into the jacket a foot or so for take off and 2 foot or so for return. I'm just not sure what you would recommend for clearance under the fire box.

3: this unit is intended to run the radiant heat in the basement and first floor, baseboards in two bedrooms up stairs and the domestic hot water for showers, faucets, etc... I'm figuring an 80-100 plate water to water heat exchanger would be sufficient.

Is the heat exchanger placed out at the boiler, in the enclosure (shed) or is it better to have it in the basement right near the existing plumbing, oil boiler, etc...? I'm planning to run 1" pex. The boiler will be almost level with the house 45 feet from the outside of the house foundation. It's approximately another 15 feet in the basement to the plumbing connections.

4: I purchased a "Honeywell 6006" aquastat with the immersion probe/well. The aquastat has a probe hard wired off the back which inserts into the immersion probe/well. Where is the best location for the probe/bung? Directly over the takeoff bung?

5: the boiler will be air fed by a blower under the grate. I was thinking of using a throttle body off a Suburu Forester to act as a baffle. The butterfly will be opened and closed with an actuator/solenoid and the blower will be attached to the throttle body "throat/rim".

When the blower shuts off and the butterfly shuts, it effectively seals off any air supply. Does the boiler require a small amount of air or draft while the boiler is "idling"?

I know the whole idea of a blower and butterfly is to kick the fire up when the water temp drops below a certain point and then to lower the fire once temprature is reached. I'm curious if an "auxiliary" vent or similar point of air intake is required to basically prevent the fire from suffocating between cycles. Is it desirable to have all air shut out between cycles?

These are the main questions I have right at the moment. As I said, I have never attempted this type of build before so I hope this will work the way I want it to.

I have many years of fabricating experience but basically no experience burning wood.

Please give me whatever you got.

Thank you very, very much!!!

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[Scott7m]

Hmm where to start

80-100 plate would be installed in the home...   But there is more to it than that, but it's pretty vast and I'm not real sure where to start talking since you are real new to this.   But you'll have a main loop with a and likely loops coming off of the main loop once inside, but we'd have to know more about it

No you don't need to allow any air in the stove during idle, the teeny tiniest of leaks can make a stove overheat.

As far as air intake, hmm...  I guess that would work but there are actual stove fans, solenoids, and flaps that aren't that expensive.  And we know they work


In regards to the aqua stat it can install right over the bung you put in with that style..  As far as placement most I've seen are on the back of the boiler about 12-15" below top of water jacket.

As far as adding fins on the firebox, I don't see that would be a huge advantage but it may not hurt to try

[Acetylene420]

I thank you very much for your input!

You have answered my questions quite well.

Any chance you know a model of blower with a flap which is tried an true? I've seen a few while searching around online but haven't decided which one is best. I'd like one which would offer an airtight seal and reliable operation.

Thanks again.

[Scott7m]

Id just have to look

we usually sell the customer a fan kit like youd see on a natures comfort

it includes fan, solenoid, and rubber disc to seal off the fan