Heat loss on underground piping

[larryjbjr]

*sigh* I was told it would use a lot more than my wood stove, but I never dreamed it'd be that much.

Maybe I should just sell it while I can....




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[larryjbjr]

The OP wouldn't disclose which boiler he is using....

No secret. It's a Johnson Little John. About 17 years old.

I got it last month for $500.






Pretty good shape for its age I think.

 

[Bad LP]

That's a lot of wasted energy IMO not to mention the personal time and effort cutting wood.

 

[Ashful]

*sigh* I was told it would use a lot more than my wood stove, but I never dreamed it'd be that much.

Maybe I should just sell it while I can....




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Don't take my word for it, I've never owned an OWB. Just regurgitating things I've read here.

 

[salecker]

One of the problems with efficiency and outdoor wood boilers is almost everything that burns wood outdoors is lumped in as a OWB.
Boilers are a closed system and run under pressure.
Wood fired water heaters are an open system.
My Econoburn is a boiler that was designed to use indoor or outdoor.Under the skin the inside and outside models are the same.The efficiency of the Econoburn is claimed to be in the 80's percent.
A Garn is a wood fired water heater,no pressure open system.From what i have read it would be hard to top it's efficiency and simplicity.
Then there are many others that ride the coattails of quality OWB's and Outdoor wood-fired water heaters.They can usually be singled out because they have a huge firebox that the owners usually fill up with anything that will smolder, most of the time it's wet wood because dry wood disappears in them.
Our town has a big "Central Boiler" OWWH that tries to heat a cafe and motel.It is the biggest one they make.There is always a huge smoke cloud coming from it.Right now there is a huge pile of green popular that will be fed into it this fall/winter.They used bubble wrapped lines which are exposed without insulation where they come out of the ground and go into the buildings with a 90 fitting.
From October on i fill the oil tank at the Motel every 2 weeks because the motel will run out of fuel if it gets cold.These aren't big buildings,old yes but have had some insulation upgrades and window upgrades.They burn/smolder about 30 cords a winter plus the oil.There is creosote running down the short little chimney,and out around the door.Totally inefficient system that costs them more to use to heat the place then if they used all oil.
This business was my mom's,it is leased out.Previous owners(they had a contract to buy the business but weaseled out of the contract) had the "Central Boiler" installed by a company that went out of business.My Mom died and it is now my brothers and I's headache.I really hope this batch of Chinese people actually step up and pay for the place(another agreement of sale).
If for some reason we ever have to heat the place the OWWH will never see another stick of wood.

 

[StihlKicking]

Unfortunately most outdoor wood boilers have a efficiency rating between 28 and 40 pct!

I know my OWB is very inefficient compared to most in door wood stoves but I have a hard time believing it's that low. I'm guessing mine is more like 65ish. 2800 sqft, well insulated, 10 cords a year burning 365. If anyone can run numbers to know the efficiency of my OWB for sure I would really appreciate it.


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[maple1]

I know my OWB is very inefficient compared to most in door wood stoves but I have a hard time believing it's that low. I'm guessing mine is more like 65ish. 2800 sqft, well insulated, 10 cords a year burning 365. If anyone can run numbers to know the efficiency of my OWB for sure I would really appreciate it.


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Sounds like about the same size as my house - which is 2700 sq.ft. in two stories, plus another 1500 in the basement (unfinished & not directly heated), 'typical' 20 year old construction. I burn between 5 & 6 cords. Going all summer would be maybe another cord. I think my boiler is rated around 80%. Not sure they can be directly compared though, likely some apples & oranges stuff going on.

 

[larryjbjr]

I think my boiler is rated around 80%.

Which boiler do you have?

 

[larryjbjr]

I've heard that you can improve efficiency by lining the firebox with fire brick.

Anyone know if there is any truth to that?


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[maple1]

Which boiler do you have?

It's in my sig - Varmebaronen UB 40.

 

[larryjbjr]

OK, sorry I don't see any signatures using phone


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[maple1]

I've heard that you can improve efficiency by lining the firebox with fire brick.

Anyone know if there is any truth to that?


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Maybe?

The thing about boilers vs. stoves & furnaces is - they have a liquid cooled firebox. That's a way of looking at them that many don't take. So the water jacket, while necessary for heat exchange in a 'conventional' boiler, is also a hindrance to a good hot fire. A fundamental design aspect of most efficient boilers (gasifiers) is separating the insides into 3 'zones' if you will - first is the firebox where the primary fire is, then a secondary chamber completely surrounded by refractory where the gases from the first fire pass to and can fully combust without the liquid cooling effect, then on to the heat exchanging area where most of the heat recovery takes place via heat exchange tubes.

So - if the inside of the firebox on the conventional boiler is big enough, you may be able to play with some firebrick to build a chamber around the fire where most of the burning can take place, then if the gases can still pass by the metal (heat exchanging) surfaces of the firebox from there before they go up the chimney, you might get some improvement. But you could also be making a creosote trap doing that, if your return water coming back to the boiler is less than 140° for periods of time. Maybe you will get some feedback from someone who has just simply lined with success.

 

[larryjbjr]

I think I'm just going to sell this thing. So I just put it on craigslist.

Anybody around the Sheboygan Wisconsin area looking for an outdoor wood boiler? [emoji16]


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[StihlKicking]

Not from there and not looking but I just like saying Sheboygan! [emoji3]


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[Ashful]

Running the Englander again this winter?

 

[larryjbjr]

Running the Englander again this winter?

Yes, definitely planning to run that this winter.

But, I was thinking if I could just sell the outdoor wood boiler and everything for at least what I have in it then I would buy a new high-efficiency LP boiler. I have a friend in the HVAC business who has offered to sell me one at cost. Just waiting now for him to give me a quote on how much that will be.

I really like the idea of an outdoor wood boiler. But I just don't think I'm ready to handle 15 cord of firewood a year. Especially since this year I will have to buy almost all my wood. At $150 per cord, I won't be saving any money.

Now, in a few years when my boys are old enough to do most of the work I might just get back into it. [emoji16]

 

[Ashful]

I really know nothing about them, other than the folks I've known who own them seem to love 'em, but what about an indoor wood boiler?

LP is convenient, but it ain't cheap around here! I pay far less per BTU for oil, than I've ever seen quoted for LP.

 

[larryjbjr]

I really know nothing about them, other than the folks I've known who own them seem to love 'em, but what about an indoor wood boiler?

LP is convenient, but it ain't cheap around here! I pay far less per BTU for oil, than I've ever seen quoted for LP.

I don't really know much about indoor wood boiler. But I have thought about a wood furnace. Actually my friend is selling one for a reasonable price. But, I would still need wood for this winter and I just don't have anything ready to go yet.

Around here we had a really wet spring and early summer. Plus with me working a lot of overtime I was never able to get out and get firewood. So I think for this year I'm just gonna have to heat with propane again.

 

[leon]

I've heard that you can improve efficiency by lining the firebox with fire brick.

Anyone know if there is any truth to that?


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When I had my indoor wood boiler I filled the fire box half full of full firebrick to the flue breech after I laid a 2 by 12 by 12 piece of channel iron over my shaker grate frame and after doing this I had a hotter fire with less smoke and I wish I had done this in 1983 when I had the boiler installed.

You will see a huge reduction in wood burning once the firebrick gets hot it will burn the gasses that are normally lost when burning and you will have less smoke.

I will be adding firebrick to the coal stoker boiler this year as well.

At the rate your going you will be better off building an 83 foot long pipe supported trellis to grow grapes on and also carry the tubing in a narrow closed box made with 2" by 8"s for the top and side and bottom that would have the tubing foamed in place in the wood box made from pressure treated lumber..

 

[larryjbjr]

So here's the math. Assuming it's actually 1.5* temp loss.

I'm guessing you'll be circulating around 8GPM so...

8GPM x 8.33 (weight of 1 gl of water) x 60 (minutes per hour) x 1.5 = heat loss of 5,997.6 btu/hour

5997.6 x 24 means you'll be losing 143,942 btu per day.

I'm not sure I understand this part. Why would you multiply that times 24 hours when the pump will not be running 24 hours.

Typically my furnace runs less than 20 minutes per hour. So that would be multiplied times eight hours right?




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[maple1]

Most OWB people run their pumps 24/7. I don't think you can directly correlate current furnace run times with OWB circulation times - for most of the heat loss and inefficiency reasons already talked about. Together with - the direct heat your LP furnace can supply in 20 minutes is bound to be a lot more than an OWB exchanger (absolute max maybe 180°?) can supply in those same 20 minutes.

 

[NP ALASKA]

I owned a CB 7260 for about 7 years in the Interior of Alaska.
4 buildings- over 11,000 sq ft
Pumps run 24/7
One run was 150’ underground with another 120’ inside building

70 cord per year

Sold it and ran as quick as possible

I compare the stack output of that old unit and my Effecta gasser- no comparison
The OwB is obviously a non efficient device

 

[JohnDolz]

I owned a CB 7260 for about 7 years in the Interior of Alaska.
4 buildings- over 11,000 sq ft
Pumps run 24/7
One run was 150’ underground with another 120’ inside building

70 cord per year

Sold it and ran as quick as possible

I compare the stack output of that old unit and my Effecta gasser- no comparison
The OwB is obviously a non efficient device

Face Cord or Full Cord? Either way 70 is a crazy # !

 

[warno]

OK, sorry I don't see any signatures using phone


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Turn your phone sideways.

 

[NP ALASKA]

Face Cord or Full Cord? Either way 70 is a crazy # !

Full cord
Was a vicious few years