An easy wood fired water heater design

[solidwoods]

I use a wood fired water heater, its a Taylor.

I heat an 4000sq' shop, 4000sq' (1890) 2 story, 2000bf lumber kiln, hot water for dog grooming buis.

nuff of that.

I don't like the "underwater campfire" design for home built.

The mfrs. of metal WFWH's have 1 design consideration that has to be met, portability.

This comes with prices.  

Compact.

Lots of welding/metalworking

Anyone build a fixed type like this?

Concrete block walls- about 4' x 8' inside dimensions.  Here its 2' to the rock so I would dig to the rock and set the block on the rock, no footers.  Walls about 3' high above grade.

back fill with dirt to outside grade.

Fire brick lined walls (no top yet)

Top is water filled exhaust heat exchanger (box of drinking straws design, vertical).  1" steel pipe could be set inside the box for extra heat exchangers (they are pre threaded, just bend to fit inside, make both ends exit the box and plumb/manifold them together with pex)

Burn area is 1 or more full length trough.  Made from fire brick. set about 2' off the floor.

Chip feed to the trough (how later)

Auger ash out with full length auger that is about 6"+/- your ash pan above grade.

Bottom line I'm not worried about the btu do-ability of this (thats no prob)  

BUT  finding a block is the question.  

Do you think concrete block would take the heat?  Even if it is F/B lined.

Thanks

jim

[satchel]

i think it would work,with fire brick lining the block.not so different from masonry stove designs.have roughly the same idea in mind.keep me posted.

[mikey ny]

I think it is a great concept. Maybe similar to the hasha? I think the block would hold up well, maybe you could double line it with fire brick for longevity. don't forget all concrete products, especially block are vunerable to exposure to water. Concrete block can actually "rot" from water damage so you might consider some type of isolation barrier on the outside of the block if it is below grade. Most new home foundations are coated with some sort of asphalt product to protect it. One area of concern I would have is heat loss from the entire unit. All efficient boilers have a significant amount of insulation around them. Of course if it is in the living area, heat loss is into the house is a good thing. There is nothing better than a big heat sink in the house to radiate all day long. "Portability" is a interesting concept also. My Hs Tarm weighs somewhere around 1500 lbs. To some people this is extremely heavy but to others it is just a hand truck and a length of chain away from being delivered to your basement. On the other hand, A pallet of block and the rest of the components to build an on site fabricated unit like you propose  is a whole different ball game. I would love to hear about your combustion chamber design or configuration of it, if you are willing to share it with us. There are a few tried and true designs out there that have little room for improvement, in my oppinion anyway.

[phil b]

Just for grins, you might check out the HASHA. It sounds similar to what you want to do and it's been around since the '70s.

[JSNH]

Fire brick works great at retaining heat. I have a wood furnace and it is a forced air burn. The fire bricks in the fire box glow pink when I am burning but the outside of the furnace remains only warm. The fire brick is up aginst the stove wall which is thin 1/8" steel then 1" of fiberglass and sheet steel. I have run this for 98% of my heat for 16 years and have only replaced a few bricks. Past the fire box the smoke goes into a secondary chamber that is fire brick lined and threw a triple pass heat exchanger. It is a Dumount boiler they are out of buisness now but maybe there is some info on the web.

[nanotech]

I work at Woodmaster ( http://www.woodmaster.com ) and one of the stoves we build is a corn burner.

Now, one thing to know about corn burners is that they burn VERY hot.  VERY, VERY hot.  And on our corn burners there is only a 2" layer of fire brick.  It is VERY effective.

Fire brick an also be made to order in any shape.  It doesn't have to be in a brick shape.  The section we use at the back of the fire box is shaped in a big hollow oval with the chimney hole in it.  And the back panel has the two holes for the augers to come through.

I'll see if I can find out on Monday what company supplies ours.

[whatsnext]

Just curious but how hot is VERY VERY hot? Woodmaster doesn't make mention of a firebox grinder that a corn stove usually requires. Do you know if it has one?

Thanks, John...

[nothing to lose]

On the subject of fire brick, if you need much of it you might want to look into making your own. Several easy cheap ways to make a great brick and you can shape it however you want it. Around here I think I could buy gold bricks cheaper than fire bricks when I want to buy one, which is why I don't buy them.

I don't have the exact receipe on hand, but clay sand and a bit of grass or straw is one way. The straw or long grass is to help hold it together while it dries and untill fired, then it basically burns out, the clay and sand form a nice solid brick.

Like I say, various ways to make your own, if you want to give it a try then look for it on sites about metal casting. Our homemade fire brick stands up to the heat of melting aluminum I think it should do well for a water heating fire

Some what like making ceramics, it's not much untill fired, but then you take a ceramic  crucable and fill it full of aluminum chunks then heat it in the foundry over charcoal till the aluminum melts and then you pick it up and poor it. Using tongs of course. That's red hot also maybe more.

The homemade fire brick should do very well to protect your concrete block walls if you choose to use it, also you can make blocks/bricks any size you want.

[jbear]

Dont know if you have started on your stove as yet but here is a warning.

I am a retired contractor/mason, never seen ANY kind of concrete OR concrete block that will take much heat. You can get with any block dealer, tell them what you are doing and the can design a block to withstand the heat with add-mixtures put into the batch as they mix for the run of block. Expensive. Same with concrete, form up your wall's after you pour the floor, pour the walls solid. The concrete plant can go back thru there engineers (whoever they buy there cement from) and design a mix that will do what you need, Not much more of a cost factor then regular concrete.  Why not just build the thing out of refractioners concrete wich you can get in 80lb. bags and the exterior could be of shot-creet?

[BigBreaker]

I'd pull the heat away from the steel with a boiler.  Boiling water will keep the connected steel below 220 degrees and you can route the hot steam into the house very efficiently.  Plenty of the steel enclosure will still get up to 300 degrees but that is still low in the scheme of things.

Unless the boiler runs dry (and it NEVER should) you shouldn't need to worry about heat in the masonry.  Refractory concrete is cheap - so is fire brick.  Just make sure to keep moisture out as best you can.