Heat Fins?

[Todd]

http://cgi.ebay.com/Heat-Fins-Energy-Saving-for-Wood-Stove-pipes_W0QQitemZ140287693844QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item140287693844&_trksid=p3286.c0.m14&_trkparms=72:1205|66:4|65:12|39:1|240:1318|301:0|293:4|294:200

Any of you old timers remember these? I was cruising through E-Bay and saw this. Never seen it before and I don't understand how they could increase efficiency?

 

[Vic99]

I'm not an old timer, but I imagine that the idea is to increase the surface area that radiates heat into the room. Downside, of course is that the stove pipe will ultimately get cooler and thus increase the rate at which creosote builds up.

 

[Backwoods Savage]

Yes Todd, I've seen them, or some very similar. So I was told though, they did very little good and weren't worth the money spent on them.

 

[EddyKilowatt]

It would be interesting to see the test data to back up the claim of 3000 BTUs per hour. In principle these look like a simple low-tech way to get heat from the pipe, but that's not always a wise idea.

Every stove sends some waste heat up the stack -- it is required in order to develop the chimney draft that draws air through the stove. Waste heat is also required to keep the stack warm enough to avoid condensation and creosote.

Some stoves in some installations might send too much waste heat up the stack... leading either to excessive draft or to excessively hot smoke (hotter than needed to avoid condensation) exiting the top of the chimney. In that specific case, devices like these Heat Fins, or any number of other heat-recovery schemes, might help reclaim some of the waste heat. 3000 BTU is nothing to scoff at, that's 10% of a typical stove's mid-range output.

But one wouldn't want to slap on these fins willy-nilly without pretty good knowledge of your system and how well (safely) it is working in its present configuration.

Eddy

p.s. The power plant across the street from me has a heat-recovery device the size of a Ferris Wheel to reclaim waste heat from their smoke. But they have a forced-draft boiler (not natural draft like our stoves), they burn gas instead of wood (i.e. they have clean smoke)... and they spend about a million dollars a day on fuel, so they worry about every .01% of efficiency.

 

[fossil]

...p.s. The power plant across the street from me has a heat-recovery device the size of a small gymnasium to reclaim waste heat from their smoke. But they have a forced-draft boiler (not natural draft like our stoves), they burn gas instead of wood (i.e. they have clean smoke)... and they spend about a million dollars a day on fuel, so they worry about every .01% of efficiency.

You in Moss Landing, Eddy? Rick

 

[EddyKilowatt]

You in Moss Landing, Eddy? Rick

Yep! 'Big Mo' is just across Hwy 1... I was referring to Units 6 and 7 which are 750 MW Rankine-cycle steam units built in 1967. Was priveleged to get the "cook's tour" from a colleague once when they were down for overhaul... we went everywhere in that plant and I mean we stood *inside* the firebox and talked to guys welding tubes, we stood at the bottom of the stack and looked up 500 ft at a tiny circle of sky, we talked to the guy doing the turbine overhaul and gave the thing a spin with our hands... it was a pretty memorable day. You'll notice I edited my post to better describe the heat recovery gadget, which is a huge rotating sieve-like affair that collects heat from the exhaust and transfers it to the intake air. Their *firebox* is the size of a small gymnasium, though... if a gynmasium was stood on end the long way... and completely filled with blue flame (with orange-hot walls) when they're cranking.

Eddy