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Author Topic: blasphemy - woodstoves  (Read 9895 times)

mikenash

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blasphemy - woodstoves
« on: November 21, 2017, 07:03:44 AM »
Don't know if this is kosher or not . . .

But I would guess we have a bunch of off-grid folks here

My last three houses have had increasingly-modified woodstoves.  The sort with ovens & wetbacks . . .

But for the "cabin" I am pottering along with, which is my "retirement" project, I decided the way to get the features I want is to build it myself.  So you can get things like the heating-rate of the wetback just right, and the size of the firebox just as you want it . . .

As you can see, it's still in the "build" stages, but last weekend I ran it for an evening after connecting up the wetback (a bit rough as yet) and the heating rate for hot water seems almost perfect

Will pictures show here?  I'll press "post" and we'll see

dieselspanner

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Re: blasphemy - woodstoves
« Reply #1 on: November 21, 2017, 07:29:53 AM »
Hi Mike

Not only do I not know, 'Frankly Scarlett, I don't give a damn'

I don't think anyone who uses this site lives, eats, sleeps and dreams of the CS Lister to the exclusion of all else. It's an interesting membership with a wide range of interests and I doubt if there will a great deal of negative reaction.

I'm in the process of 'negotiating' a sort of off grid barn, up here in the Pyrenees. I suspect the locals up here are much the same as as those who live in the Outback or up in the Appalachians. Just 'cos I've been here 6 years don't mean I get the sort of treatment reserved for locals (Those with four or more generations in the local cemetery) so it won't go at the speed of Glort's move across town. I'll be lucky to have it sorted by the late spring.

Anything you or any other member wish to post on any blasphemous subject is fine by me, and if I learn just one thing from a thread that'll do nicely.

The photo's worked and it looks like a nice job, keep all the information and details of performance in service coming.......

Cheers
Stef

Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

mikenash

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Re: blasphemy - woodstoves
« Reply #2 on: November 21, 2017, 07:55:33 AM »
What was interesting was the combustion process.

I have always had woodstoves which were adaptions of the "coal range" which was the NZ standard for a century or so.  The small fireboxes were made for coal and "breathed" through a grate at the bottom.  I have always built steel-plate welded extensions onto them to burn larger bits of firewood and they have worked well

This one, however, has a larger firebox and it didn't want to combust properly - it just wanted to make charcoal in its trail runs.  So I added the "rotary damper" on the front of the firebox door so it would have an airflow across the top of the fire - that seems to fix it

I suspect there is much to learn.  But, since it's just a whole lot of bits of steel welded and bolted together, it's no big thing to cut-and-weld as required to make changes

I made the wetback from 10mm 316 plate welded with "stainless" rods on the arc welder, but it's only loosely bolted to the rest as I reckon its rate of expansion and contraction might be different to the main structure

Lots to learn . . .

starfire

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Re: blasphemy - woodstoves
« Reply #3 on: November 21, 2017, 09:03:28 AM »
Good evening Mike, awesome job, and I bet lots of fun too.
When I lived in Haast, the dude that owned the motorcamp had some water heaters made. These were a double skinned stainless drum, water circulated in the perimeter gap producing prodigous amounts of hot water burning with driftwood from the beach as fuel.
Another one that took my fancy I saw in Ozz, this design modeled on the old NZ railways thermette, only bigger. The "cone" held around 20 gallons of water, this boiled inside 20 minutes with just a bucket of wood chunks, It was around 1 meter tall and maybe 400mm at the base, chimney exited the top.
Coal and wetbacks are as common as mud here on the coast, yours is very good and will work well. Just vent the hot water cylinder really well, you will have an excess in winter.

A funny story proving we can all learn.
Neighbour showed me his wetback installation.
That wont work I said, the 44 gallon drum as your hot water tank will rust away and the plastic pipe you have used to plumb in the hot water will melt with the heat.
No it wont he said, and dismissed me.
Weeks later I went over again. The plastic pipe was now rock hard with repeated heat cycling, easily as good as a metal pipe, and the drum had no rust, hot water has no free oxygen to corrode anything.
Twenty years later, its still working fine.
Mike, you have over designed this....... :)

mikenash

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Re: blasphemy - woodstoves
« Reply #4 on: November 21, 2017, 03:27:03 PM »


"over-design/overbuild" is my middle name. Starfire

But you gotta keep your eye on the objectives . . .

Hot water is not the aim.  Free hot water is just a handy by-product of a process that keeps my shed warm and cooks the dinner.  As someone who has had/modified almost 40 years' worth of "coal ranges" I know that the modern ones - the Don Harry/Otago Castings version of the "shacklock" - produce too much hot water as they are designed to cook, heat house and produce hot water for a couple of Otago farming families snowed in for a fortnight in winter

I was always telling one of my kids "go and have a shower" to get rid of some hot water.  In the last place I put a radiator in the bathroom to heat towels and radiate some warmth and just trickled water "to waste" back into the storage tank outside just to get rid of it

This one I have sized the wetback to about 40% of one of those.  In about five hours of burning it'll heat 180L of water to "bloody hot" and that's about right

My water comes from a spring up the hill at about 2 bar and I have a big open vent at about 4 metres with the pressure-reducing valve at 3.7 metres I think.  Should be OK

Apart from breaking my ass carrying the bits in to assemble, there's no downside to the heavy construction - I figure it is "heat sink"

The wetback fittings transition from 40mm Galv BSP to 32mm copper with the use of "Starkie" compression fittings made in England.  I had to order them in and they were $100 each - but the ones on the shelf in the plumbers' merchants were a lightweight Chinese imitation - even the counter bloke looked a bit embarrassed about them

Time will tell :)

mike90045

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Re: blasphemy - woodstoves
« Reply #5 on: November 21, 2017, 08:49:57 PM »
We heat with a Masonry  Heater, a honking big lump of brick and refractory, and we added a hot water loop to it.
The principal behind masonry heaters is large thermal mass, and convoluted flue to heat the mass.  The wood is loaded once, sometimes 2x a day, about 30 lbs ( I use 5 gal plastic buckets,  balances the weight nicely, keeps the wife's floor clean) 2 buckets is a very full fireing load. The air vents opened up, and the fire burns out in about 2 hours, when all vents close down.  The intense heat is stored in the masonry, where it is released over the next 20 hours.  A even, wonderful warmth, like sitting in the sun on a cold day.
 The SS boiler loop, is thermalsiphon plumbed to a 80 gallon tank, which preheats water to about 100F before it goes to the tankless heater.
 Disadvantage - takes 3 days firing to slowly warm it up. 
 Advantage - can skip a fire and you don't get cold. 
And flue cleaning, only every couple years, burns so clean, the sweeps can't believe we use it (even though its full of ash in the fire box)

open access album:
https://www.facebook.com/media/set/?set=a.383468711726588.86888.120212794718849&type=1&l=c762d10b5f


BruceM

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Re: blasphemy - woodstoves
« Reply #6 on: November 21, 2017, 10:02:48 PM »
Miken-  Sweet cabin with spring water at 2 bar (30 psi)!  You've got a LOT of vertical on your land.  Very impressive all in one wood stove design. 


mikenash

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Re: blasphemy - woodstoves
« Reply #7 on: November 22, 2017, 04:56:54 AM »
Thanks, Bruce

That beautiful clean spring water is half the reason I bought the property.  If you have an off-grid place and don't need a water pump or a water tank you're half-way there

The woodstove is rough but will get better.  I wanted "compact" which is hard with conventional wood stoves so I built the firebox/oven back-to-back and there's a labyrinth of space around five "sides" of the oven box for hot air to travel enroute to the flue.  Once I'm happy with the firebox/top-plate/wetback process I reckon there will be some dismantling and building of dampers to get the best out of it

Mike90045 those big furnaces function magnificently - but they're not right for my purposes.  I want something that will roar fiercely and heat up the top plate and oven as my main winter cooking tool in a hurry

13 years in my last place and 15 years in the place before that I had modified "Shacklock" stoves with big fireboxes, fierce burns and bone-dry firewood.  Hand on heart I can attest I never cleaned either of their flues in all those years.  Dry wood is the key, of course

mike90045

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Re: blasphemy - woodstoves
« Reply #8 on: November 22, 2017, 08:04:57 AM »
Once you have flowing water, that's more than half the battle won.  Lucky you.

BruceM

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Re: blasphemy - woodstoves
« Reply #9 on: November 22, 2017, 03:29:49 PM »
I have to pump from 200ft, and my 2000 gallon tank on the  hill gives me just 12psi (12/15 bar).  With oversized pipes 12psi works fine.  Pulling/resetting the pump is now up to $750. US.

You're right, MikeN, good quality water (at 2 bar/30 psi pressure!) is a HUGE PLUS  for an off grid property. Do you even have a storage tank or just a catch basin for the spring feeding your supply pipe?  I'm jealous!




mikenash

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Re: blasphemy - woodstoves
« Reply #10 on: November 22, 2017, 05:19:49 PM »
It'a real bonus, Bruce

The hillside up above my flat bit is dotted with springs and the previous owners developed the best of them

They got a digger in and dug a hole you could dump my Camry into, let it run for a while until it was clean and then just made a drain out of perforated "Novaflo" drainage pipe out of the middle of it and filled the whole thin up with pumice rocks then fenced it off to keep stock out. 

Water flows into a tank that runs three households and a plant nursery, then it overflows into a smaller tank that feeds stock troughs on two properties

Maybe it flows a litre or two a second?  Although it doesn't sound like much it flows 24/7, so maybe it would fill one of your US 55 gallon drums every few minutes

Every time I go there and turn on the tap I appreciate it.

Next time I'm up I'll take a photo of the hillbilly direct-on-line solar shower lol

Cheers

BruceM

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Re: blasphemy - woodstoves
« Reply #11 on: November 22, 2017, 05:34:19 PM »
Impressive flow from a spring...a well chosen home site! Show us more!

starfire

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Re: blasphemy - woodstoves
« Reply #12 on: November 22, 2017, 11:26:56 PM »
Also Mike, meant to tell you. in the days of sphagnum moss exports from down here, a common method to dry this stuff was a series of repurposed car radiators hooked in to a wet back in a coal range or pot belly. The water was just thermo syphoned around the drying shed. A similar idea may be useful for you winter heating. .... it gets cold up there. Old school radiators are still fairly common at scrap metal dealers, these easily mount to a wall. I use one here, except its the Lister supplying  the hot water.

vdubnut62

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Re: blasphemy - woodstoves
« Reply #13 on: November 23, 2017, 01:07:12 AM »
Looking good Mike! I used a forced hot air wood furnace here in our old house for years, never was able to work out the hot water loop though.

Ron in TN
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mikenash

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Re: blasphemy - woodstoves
« Reply #14 on: November 23, 2017, 04:14:09 AM »
G'day Ron, G'day Starfire

My shed/house/workshop up there - it's one of those cut your suit to suit your cloth kinda things

I have never liked big houses with hallways and doors and corners etc etc.  I especially think a hallway is a hell of a waste of space.  the last place I built was a bit open-plan-ish, but this one is very much so

I got one of those companies that make "pole shed" barns to build me one 12 metres X 7 metres so I had an open, self-supporting structure with no internal walls at all, so no requirement for the internal walls to hold the roof trusses up or anything like that

I'm sorta half-way through making it civilised - putting in a  floor on piles with underfloor insulation, building a front wall with four sets of glass french doors to catch the sunshine etc etc

But the big thing I think, is it's only 72 square metres - so won't be hard to heat, I hope

Time will tell

Cheers