Need help with design/process of a system

roughidle Posted By roughidle, Nov 2, 2017 at 3:02 PM

  1. roughidle

    roughidle
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    IMG_20171102_144721.jpg Quick Back Story:

    I've grown up burning wood at my parents house, unfortunately I'm not too well versed on the physics and processes of it all. My father built the wood stove I used to heat their house as a child and it was enough for their small ranch house.

    I've lived in a development with gas heat for the last ten years so I've been spoiled to say the least. My wife an I have bought a house out in the sticks that had a coal stove installed that I've replaced with a simple Alaska Wood Stove. Not terribly large, but it's what I have to work with for the next two years as I have to put the bulk of my funds into the house itself to make it more livable for our family. It is a two story 2000 sq ft 4br house.

    To the meat and potatoes:

    I'm installing a central A/C unit with it's own air handler and fan and will be running ductwork into the house while I've got everything torn apart and I would like to do something like what you see done with the outdoor wood boilers if possible like running an exchanger into a plenum sitting on top of the (to be installed) a/c air handler. Please see the sketch and let me know if I'm on the right track.

    Thanks
     
  2. maple1

    maple1
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    If you are going to be heating that coil with your wood stove I think you will be disappointed with the results.
     
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  3. Bob Rohr

    Bob Rohr
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    Piping wise, the pump should be just downstream of the expansion tank, pushing into the coil.

    These wood stove HX can be very unmanageable. The main issue is when the home is heated to temperature, the pump shuts down, now you have a very real potential to flash to steam in the coil inside.

    The of course relieves pressure and water, now you risk dry firing the coil.

    Approach with caution.

    Ever seen the Mythbuster episode where the over heated water heater heads to the moon? :)
     
  4. roughidle

    roughidle
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    How does an outdoor unit manage the on/off of the water circulation?
     
  5. roughidle

    roughidle
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    Would installing an old water heater as a holding tank and allowing the pump to run continuously instead of just when the fan is running remediate the potential of overheating at all?
     
  6. maple1

    maple1
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    It has a bigger volume of water. And it shuts down combustion air. And most boilers have a means to dump excess heat.

    Seriously - I am quite sure you will find you will not get enough heat out of this setup to make it worthwhile.
     
  7. roughidle

    roughidle
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    Does anyone have any ideas that I could implement?
     
  8. maple1

    maple1
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    You might see a little bit of remediation but it should not be trusted. A simple short power outage would likely be big trouble - as soon as water stops flowing through the loop there could be a flash event in the piping in the stove with destruction of some sort possibly not far behind.
     
  9. SuperSpy

    SuperSpy
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    As others have posted, this setup seems really dangerous.

    There's not enough water/heat storage in the system. Commercial units generally have over 100 gallons of water to act as a buffer between the time the water reaches it's high temperature mark, and the time the fire dies down enough to stop producing heat. My outdoor unit, for instance, holds about 160 gallons of water with a fire shut-off at 185F, yet will many times heat the water to around 200F before the fire actually dies down and stops producing heat, even though it's air supply has been totally sealed off.

    Using a set of coils inside the firebox is likely to not have enough surface area to draw a significant amount of heat into the water compared to the furnace heat exchanger's ability to remove it. Again, most commercial units completely surround the firebox in a water jacket to achieve reasonable BTU outputs.

    I don't see any method to control the fire. If you just plan on using this to piggy-back on the existing stove, I think you will constantly have problems fighting boiling water, which will force you to constantly re-fill it, which is going to cause problems with scale build-up potentially clogging the system, causing more boil-overs.

    A less problematic system, depending on the distance between stove and furnace, might be to just empty copper from the furnace to the heat exchanger, relying on the copper to transfer the heat without all the hassles and danger of water/steam. This would require a lot more copper, and would only really work if the stove and furnace were really close. However, then you would have to worry about potentially having a very hot surface (and air) in your heat ducting, which could be dangerous in it's own way.

    If it were me, I'd just direct some of the furnace's air towards the stove and rely on convection, but that's not going to heat an entire house.
     
  10. roughidle

    roughidle
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    Ok, thank you all for the replies and I've moved on to accept I can't be a cheap skate on this. However, I do look for good deals when I can. I've found a Tarm 2000 wood gasifier for sale. My main problem with it is the weight and logistics of getting it from where it is to where I am. It looks like it will do everything I want it to and will be able to plumb it into the air handler.

    Any tips to move this thing out of a basement and into mine? I've got to haul it about two hours away. The truck and trailer I can take care of, it's the moving to and from....
     
  11. maple1

    maple1
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    Are you sure you have everything figured out for this? From proper chimney & hookup, to overheat/dump considerations, to sizing of heat exchanger, to controls & wiring, to supply of truly dry wood? (And likely other things I didn't mention...)

    No specific tips on moving, other than to use rollers & maybe a pallet jack, anywhere you can. And don't get under it. There might be a hook on top for lifting with a FEL or the such. If not sometimes a T can be threaded into a top fitting to lift by. Manual might have hints.
     
  12. roughidle

    roughidle
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    I've got plenty of dry wood cut and stacked. From the seller he's saying for his approximately same sized house as mine he's using about 25% less wood than I currently am with my conventional wood stove. My chimney is the same diameter as the manual calls for (6" min). The heat exchanger and controls/wiring are still being built into the house (this is a complete remodel) so they will be properly sized and configured before initialization.
     
  13. nhtreehouse

    nhtreehouse
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    On moving heavy things like boilers and tanks... I moved two boilers and a 1000 gallon tank this spring/summer without the benefit of tractors, skid steers or front end loaders. It can be done with human powered tools, it just takes a bit longer.

    Picking up a used chainfall or two (I currently have three) off CL will pay back dividends. When I unloaded my Froling, I erected two masonry staging "boxes" around the back of the truck. Using my largest chainfall, I lifted the boiler straight up, drove the truck away, and lowered it down to a ramp and moved it with a pallet jack. Masonry staging is typically rated around 4 tons. Maple's suggestion of using pallet jacks cannot be overlooked - amazing tools. I could easily lift the 1000 gallon tank, which is around 1 ton empty and wheel it around with a pallet jack. One needs a smooth surface of course, concrete is ideal, but I have used the pallet jack on 2x lumber ramps to move lighter objects like boilers.

    Rollers made from sections of 1" black pipe are also very useful for these activities. I used a pile of those to move the tank around the yard here. Again, chainfalls provided the pulling power - you can use chainfalls horizontally as well as vertically. All my chainfalls are standard overhead units with an endless loop of chain. Had I the choice, I would have bought lever operated chainfalls, they are much easier to use in any position.

    Finally, get yourself a big iron bar. Mine is about 7' long and made from 1.5" black pipe. I welded the end of a leaf spring in a slot I ground into the end of the pipe. This has come in hand numerous times when I need more leverage on something. Used it last night to do the final positioning of the tank.

    Good luck with your moving project and whatever you do, don't get under any of that big iron! Safety first! (or at least second!);)
     
  14. roughidle

    roughidle
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    He's telling me this thing weighs 1750 lbs, is that accurate? I'm having a hard time finding a manual for a tarm 2000 online anywhere that gives me the specifications for it. He has one with it, but again, it's two hours away and we've not yet begun negotiations.

    Thanks,
     
  15. maple1

    maple1
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    Manual says around 1300 lbs - found manual in 2 minutes with google. Closed the window again but I think it was on woodboilers.com. Google 'tarm 2000 boiler'.
     
  16. maple1

    maple1
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    To add to the tools mentioned above (all excellent suggestions) - blocks of various sizes, and a low profile floor jack. Maybe lengths of thin wide flat bar for sliding on.

    Levers & rollers - when you get the boiler moved you can build yourself a pyramid. :)
     
  17. roughidle

    roughidle
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    Thank you - I see it now. I had seen that list and saw the Excel 2000 multi-fuel boiler, but didn't go down far enough to see the regular 2000.
     
  18. Chris Hoskin

    Chris Hoskin
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    The Excel (dual fuel) is going to be a 1500 pound lump and the Tarm 2000 (wood only) is going to be about 1000. Which are you looking at? Chris
     
  19. roughidle

    roughidle
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  20. roughidle

    roughidle
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    Tarm 2000
     
  21. roughidle

    roughidle
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    Chris - I see you're a Tarm sales guy -

    (1) he's telling me I don't need to use a storage tank (he's claiming use for 17 years without one) as the water lines and the boiler itself hold enough water that a tank isn't necessary.

    (2) I'm hoping he has a mixing valve that is included with the boiler, but if not, what will the tarm mixing valve run me?

    (3) He has a brand new pair of still crated unused left and right refractory - originals still installed and he says they still have some lift left in them. What other things should I be looking for in this boiler for possible issues?

    (4) What would a fair price be for this unit? He is still using it and says it will remain hooked up in use until it is sold...

    Thanks in advance
     
  22. Chris Hoskin

    Chris Hoskin
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    Hi Roughidle,

    1) correct, the Tarm 2000 does not require thermal storage. That being said, any wood boiler works better and lasts longer when used with thermal storage. Get a good look at the inside walls of the firebox. Ideally you'll see where the stays protrude into the firebox. If they are still sharp-shouldered (I would not expect this), that is great news because it means the boiler has not spent a lot of time idling and there has not been a lot of corrosion (result of idling). If the stays are just smooth lumps (I would expect this), you might get another 5 - 10 years out of the boiler (longer if you add thermal storage). If you can't even see the stays, the boiler is nearing the end of its life. Take a broom handle and push against the firebox wall at the rear-bottom and see if you get any flex there. If so, buy it cheap.

    2) $175 for the valve kit: https://store.tarmusa.com/collections/thermostatic-valves/products/lk-823-mixing-valve-1-union-kit

    3) Good news on the refractory. Those new left and right stones will last you at least 5 years. Once they need to be replaced you'll need to convert the boiler to a three piece floor which involves replacing most all of the refractory in the boiler and will run you about $1000.

    4) even though there is some advantage in being able to see the boiler in action, I'd say it's worth more if it is already uninstalled and sitting in the garage ready for you to pick up. Getting one of these things into/out of a basement can be a big deal. Too many variables to suggest a price, but if it has been in use for 17 years.....20+ years is not unusual, but you're almost there.

    Good luck!

    Chris
     
  23. maple1

    maple1
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    Some quick sideways input from here.

    You might not 'need' storage, but any decent boiler benefits greatly from it. Especially a gasifier. How much water is in the lines & the boiler are largely irrelevant - the boiler will shut down & idle frequently without storage.

    A mixing valve is usually a good idea, but without storage & depending on the system it is hooked to, it might not be a 'necessity' if return water is above 140 for a large majority of the time.
     
  24. Chris Hoskin

    Chris Hoskin
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    quick side-bar: if you haven't already run the duct work for central AC, you might want to consider a mini-split system for AC and back-up heat and then run panel radiators for the wood boiler (easier install and more comfortable than forced hot air). Chris
     
  25. roughidle

    roughidle
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    You wouldn't happen to have a picture of the stays in the firebox you're referring to would you?

    Thanks
     

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