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View Full Version : The HAHSA idea revisited


wdwrkr51
02-13-2007, 01:14 PM
Hey guys;

I realize that all of this has probably been tried, tested and rejected by people who know a lot more about this than I do, but I'd like to hear your reaction to some questions concerning the Heat And Heat Storage Apparatus concept.

I'd like to approach this from the standpoint of using a HAHSA to supply heat for a radiant heat system in a concrete slab.

1) Since radiant heat requires a relatively low water temperature to be effective, why not design the HAHSA to utilize a quick, hot blaze (little objectionable smoke) to move heat into the sand, into the copper heat exchange pipe, and thence into the pex tubing embedded in the concrete?

2) If a quick burn ( -as used by Finnish masonry stoves) to heat the sand would not suffice, then why not use a much smaller firebox, and burn the wood for a longer period of time, at a faster rate, and at a higher temperature, again reducing the objectionable smoke/gas pollutants and hopefully increasing efficiency over the approximate 50% efficiency these things achieve?

3) Why not use a heavy steel firebox, instead of masonry, embedded in the sand? Then, why not rout incoming air through a heavy 4" pipe and into the firebox, directing the stream at the heart of the blaze - thus "supercharging" the burn? Incoming air could be preheated by running it through the sand bed first. Draft might be controlled by dampers in the smoke chimney, I guess, but should not be too difficult to regulate at the intake pipe.

4) At the low temperatures and relatively low pressures required, why not use 1/2 or 3/4 inch copper gas line, flared ends, and tapered compression fittings for the heat exchanger, before converting to the PEX tubing in the slab?

5) Maybe the best use for this would be as a backup to a solar hot water heating system, in a closed loop, against the dark, cold days when the sun isn't much help.

All of this is predicated on building a small, tightly built, very well insulated cabin on a concrete slab that has been insulated with foam underneath and around the edges; using PEX tubing and a supply manifold to move water through the slab in a closed loop system.

I also assume the concrete block building housing the firebox and sand is well insulated inside, using foam on all sides,top and bottom, to hold onto the heat we do create as efficiently as possible. Furnace also to be located close to the cabin to reduce heat losses in between.

Wood for burning is in abundant supply at hand, needing only my labor to make it useful to the purpose.

So, Whaddoyah think???

Bill

AlchemyAcres
02-13-2007, 03:52 PM
Hey guys;

I realize that all of this has probably been tried, tested and rejected by people who know a lot more about this than I do, but I'd like to hear your reaction to some questions concerning the Heat And Heat Storage Apparatus concept.

I'd like to approach this from the standpoint of using a HAHSA to supply heat for a radiant heat system in a concrete slab.

1) *Since radiant heat requires a relatively low water temperature to be effective, why not design the HAHSA to utilize a quick, hot blaze (little objectionable smoke) to move heat into the sand, into the copper heat exchange pipe, and thence into the pex tubing embedded in the concrete?

There's 14+ tons of sand to heat, hence the long slow burn. *

2) *If a quick burn ( -as used by Finnish masonry stoves) to heat the sand would not suffice, then why not use a much smaller firebox, and burn the wood for a longer period of time, at a faster rate, and at a higher temperature, again reducing the objectionable smoke/gas pollutants and hopefully increasing efficiency over the approximate 50% efficiency these things achieve?

The firebox is large and tall to trap heat and to accomodate pallets ...usually had for free.

Burn good well-seasoned hardwood, with the HAHSA downwind from the structure...smoke will be much less of a concern....unfortunately...too many peole burn wet/green crappy wood in these things, that's going to lead to laws against them in the near future...too many neighbors bitch.

3) Why not use a heavy steel firebox, instead of masonry, embedded in the sand? *Then, why not rout incoming air through a heavy 4" pipe and into the firebox, directing the stream at the heart of the blaze - thus "supercharging" the burn? *Incoming air could be preheated by running it through the sand bed first. Draft might be controlled by dampers in the smoke chimney, I guess, but should not be too difficult to regulate at the intake pipe.

Yeah...there's a damper in the chimney...no, doubt...preheating the incoming air would take a big difference.

[quote author=wdwrkr51 link=board=ene-wood;num=1171394048;start=0#0 date=02/13/07 at 08:14:08]4) At the low temperatures and relatively low pressures required, why not use 1/2 or 3/4 inch copper gas line, flared ends, and tapered compression fittings for the heat exchanger, before converting to the PEX tubing in the slab?

I'm sure flexible pipe could be used.
I've always thought that the use of PVC for the domestic, even though it's at a high point in the sand, was a bad idea. *

5) Maybe the best use for this would be as a backup to a solar hot water heating system, in a closed loop, against the dark, cold days when the sun isn't much help.

If you're where you can rely on solar, and just consider the HAHSA a back up...I'd consider something else.* *

All of this is predicated on building a small, tightly built, very well insulated cabin on a concrete slab that has been insulated with foam underneath and around the edges; using PEX tubing and a supply manifold to move water through the slab in a closed loop system.

I also assume the concrete block building housing the firebox and sand is well insulated inside, using foam on all sides,top and bottom, to hold onto the heat we do create as efficiently as possible. Furnace also to be located close to the cabin to reduce heat losses in between.

Wood for burning is in abundant supply at hand, needing only my labor to make it useful to the purpose.

So, Whaddoyah think???

Bill

The HAHSA is well insulated.

The design has it's shortcomings....I've given up on the idea in favor of something completely differnent.

http://www.axwoodfarm.com/PAHS/UmbrellaHouse.html

I have HAHSA plans if you're interested...includes the gravity flow option.

~Martin

wdwrkr51
02-13-2007, 07:31 PM
Hey, Mr. Martin;

Thanks for sharing your thoughts on this idea. You mentioned that you had plans for the HAHSA; so I'd like to find out how to get a set for myself. Please let me know at this website, or contact me at wdwrkr51@bellsouth.net.

Thanks;

Bill