how come! wood burn stoves or pellets dont have hydronic heat exchange! it cant be my idea

tl589 Posted By tl589, Aug 19, 2006 at 10:10 PM

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  1. tl589

    New Member 2.

    Aug 19, 2006
    I'm very new to this type of heating, and looking to purchase a stove before the winter because oil sucks... On the units i have seen they all have heat shields, how come none has a heat exchange to tie into Baseboard hydronic system..(note most home's already have circulator on the loop which could be on for re-capture heat to maim boiler.) any info on the performance hearthstone products how are they.
    ibew electric
  2. MountainStoveGuy

    Minister of Fire 2.

    Jan 23, 2006
    Boulder County
    i will take a total guess, maybe because lower firebox temps caused by cold water running through them, would not make them burn efficient enough to pass epa restrictions?
  3. Roospike

    New Member 2.

    Nov 19, 2005
    Eastern Nebraska
    That was my thought .Also the outside wood burner have water jackets and dont have to worry about EPA .............. as of YET . Smoke boxes . I'm sure EPA have everything to do with it .
  4. Eric Johnson

    Eric Johnson
    Mod Emeritus 2.

    Nov 18, 2005
    Central NYS
    I did a post about six months ago on an indoor (living space, actually) boiler with a glass front that would allow you to do what you suggest. It doesn't have much water capacity, but it supposedly can produce 100,000 bts per hour, if memory serves. Imported from Europe.

    I'll try to dig up the thread and post a link.

    Other than that, I think that what MSG said is true--it's hard to get much in the way of firebox temp when you're heating water. What you propose wouldn't be the same as a boiler, obviously, but the same logic still applies.

    We've also had some discussion on this board about rigging up a domestic hot water heat exchanger to a conventional wood stove, but safety issues come into play, expecially when you're trying to run a coil through the firebox.

    If your primary interest is hydronic heat, IMO, best to think about getting a boiler instead of a wood stove.

    EDIT: Here's the link:
  5. webbie

    Seasoned Moderator 2.

    Nov 17, 2005
    Western Mass.
    In Europe it is VERY common for solid fuel stoves and fireplaces to heat some of the house through radiators and also provide DHW.

    There are two reasons why you don't see this type of product here:

    1. Installation is expensive since hot water pipes must be run into the living area - controls and pumps also must be installed.
    2. The testing of any pressure vessel is a PAIN. High costs, and considering the low sales numbers, not worth the while of the manufacturers.

    You can rest assurred it has been thought of! In fact, a number of units were on the market back in the early 1980's.

    Another problem is that hydronic heat is rare in the USA.

    All in all, it is another example of short term thinking. Most folks will burn oil until they think it is expensive, then (as Elk so grandly states) drive their Lincoln Navigator to the nearest hearth store and order the latest and greatest in $3000+ Pellet save money!

    On the other hand, Hydronic systems, Russian and Finnish fireplaces and other such "lifetime" systems are quite rare.
  6. elkimmeg

    Guest 2.

    In a burner you have electronic controls and a controlled fire box and ignition. A wood stove has too many variables to have that type of control, Your furnace only comes on when it is called for. The wood stove works constantly. there is no on off.

    Ever hear of a steam explosion? Once that water passes 212 degrees you have steam You better have a drain down system and relief blow-off valves. The last thing one wants is a pressurize 500 lb stove being launched thew the roof or exploding. I would be real careful engineering a system not designed to function that way. Yes there are true stories, where one has done what you ask and the explosion has ruined homes ,and actually launched the stove threw a roof. Me I enjoy 4th of July fireworks but see no pleasure watching my home destroyed, because one room was a little colder. My suggestion to you Is, to find out why that room is colder. There are two possibilities insufficiency insulation or insufficient baseboard heat or both. The other possibility is that room is at the farthest point in the heating zone. Too much heat was dissipated before it finally makes it to that zone. Today all heating pipes are required to be insulated to R5.0 in unconditioned spaces. You could be loosing too much heat in the delivery system outside the living space.
    Another possibility is inadequate baseboard radiators. Common baseboard radiators produce 450 BTU per ft (the builders specials slant fin 15 pack.) If pressed for wall space frett not , high density baseboard radiators can produce up to 1200 BTUs per ft .. Perhaps if the zone is too long than is can be split and another zone added to shorten the run and even out both zones.

    Point being lets figure out the problem and button up your house first. Remember wood stoves are zone heaters, auxiliary heat, that reduce to load of the main system. Trying to make the to preform beyond their limitations usually does not work out too well.

    I can help you move heat around with a few well positioned box fans. I can also help you figure out why the room is so cold. First approach would be to address, why that room is cold?
  7. wg_bent

    Minister of Fire 2.

    Nov 19, 2005
    Poughkeepsie, NY
    There are people who heat domestic hot water with coal stoves. Not sure about all brands, but I do know that many of the Harmons have a DHW coil option. I have always wondered about Elk's point with stoves like the Harmon Mark series, the 2 larger stoves in that line do have the option. Coal stoves that are hand fired are wonderful beasts. Dirt simple, and crank out a lot of heat year after year with little fuss, but you can't control the fire very quickly, so if the water temp started getting too high, I'm not sure how you would handle.

    But with the stokers I could see how it would work.

    With wood stoves, the coil would probably take too much heat out of the fire box. The only technology I can see working for wood and DHW or Hydronic heat would be one of the larger masonry heaters. But with them, adding hydronic heat would probably defeat the whole idea of the masonry heater. I think even DHW would suck a lot of heat out of the heater such that you'd likely end up running 3 or 4 fires a day instead of 1 or 2. Starting a fire in those things all the time seems like a pain, and once a day seems doable, but 3 or 4? That's a hassle.

    It sure is tempting. The one way to DHW or Hydronic heat that I've seen with wood is the Tarm system with a heat storage tank. You have an extra 300 sqft your not using in your basement and around 20 grand? THAT is a ultimate system.

    Go look at Tarm's website and drool!!! Oh, and you'll consume wood on a scale like Eric does.
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