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heat exchanger ideas please

1

1234

Jan 1, 1970
0
I have just finished installing an EPA wood stove....and I love it.
Burns for about 10 hours on one fill, keeps my living space at 20 c no
problem..the bedroom is about 16.5 c and the basement is about 6 c with
an outside temp of minus 6 c.
I am looking for ideas on a water transfer system to move some of the
heat to the back bedroom and the basement to keep ny water pipes from
freezing. I am going to use water for transfer and build some sort of
tubing to sit on top of the stove and a small circ pump. All tacky ideas
will be ignored it must be simple and safe. I was thinking of tieing
into the domestic NG water tank directly. This would give me a source of
domestic hot water as well and NG for back up. The hot water tank has an
relief valve directed to the floor allready....
 
1234 said:
I have just finished installing an EPA wood stove... I am looking for
ideas on a water transfer system to move some of the heat to the back
bedroom and the basement to keep ny water pipes from freezing.

What will you do if you go on vacation? Other heat sources might keep
fixtures and pipes from freezing with more convenience and reliability,
eg a heat tape with a thermostat, or more insulation between the pipes
and the outdoors and less insulation between the pipes and the indoors.
I am going to use water for transfer and build some sort of tubing to
sit on top of the stove and a small circ pump... I was thinking of tieing
into the domestic NG water tank directly. This would give me a source of
domestic hot water as well and NG for back up.

You might enclose the tubing in concrete with wire reinforcing. Put a wood
frame on top of the stovetop, then lay plastic film over the frame, then
wire mesh, then a tight soft copper coil that conforms to the stovetop, then
concrete, more wire mesh, and a half-inch of concrete over that. The highest
thermal resistance is likely to be between the stovetop and the new top, so
make that area large. If the new top surface is flat, it could be a nice
cooking surface, a place to put a pot to simmer without burning.

Good luck,

Nick
 
1

1234

Jan 1, 1970
0
strike 2

What will you do if you go on vacation? Other heat sources might keep
fixtures and pipes from freezing with more convenience and reliability,
eg a heat tape with a thermostat, or more insulation between the pipes
and the outdoors and less insulation between the pipes and the indoors.


You might enclose the tubing in concrete with wire reinforcing. Put a wood
frame on top of the stovetop, then lay plastic film over the frame, then
wire mesh, then a tight soft copper coil that conforms to the stovetop, then
concrete, more wire mesh, and a half-inch of concrete over that. The highest
thermal resistance is likely to be between the stovetop and the new top, so
make that area large. If the new top surface is flat, it could be a nice
cooking surface, a place to put a pot to simmer without burning.

Good luck,

Nick
 
G

Gordon Reeder

Jan 1, 1970
0
1234 said:
I have just finished installing an EPA wood stove....and I love it.
Burns for about 10 hours on one fill, keeps my living space at 20 c no
problem..the bedroom is about 16.5 c and the basement is about 6 c with
an outside temp of minus 6 c.
I am looking for ideas on a water transfer system to move some of the
heat to the back bedroom and the basement to keep ny water pipes from
freezing. I am going to use water for transfer and build some sort of
tubing to sit on top of the stove and a small circ pump. All tacky ideas
will be ignored it must be simple and safe. I was thinking of tieing
into the domestic NG water tank directly. This would give me a source of
domestic hot water as well and NG for back up. The hot water tank has an
relief valve directed to the floor allready....

A couple of turns of copper tubing around your stove pipe/
chiminy pipe might work.

--
Just my $0.02 worth. Hope it helps
Gordon Reeder
greeder
at: myself.com

Hey Dubya!
Unity means let's try to meet each other halfway
 
Gordon Reeder said:
A couple of turns of copper tubing around your stove pipe/
chiminy pipe might work.

Taking heat from the chimney leaves the firebox hotter and cleaner burning,
but 2 turns of 3/4" copper (2Pix6/12xPix3/4/12 = 0.62 ft^2) with 200 F water
in 500 F air might only gather (500-200)0.62ft^2/R1 = 185 Btu/h, like a 60
watt light bulb.

This could work better with more turns and "thermal glue" and moving vs
still hot air near the coil, but the chimney needs heat for natural draft.
We might use a double wall chimney section with a draft induction blower
(eg Grainger's $80 102 cfm 4C491) near the outlet and another fan (eg
Grainger's $61 550 cfm 4TW44) pushing room air into the space between the
pipes via a T below the draft inducer. The room air might emerge hot near
the stove, after passing over a 50' 1/2" soft copper coil tightly wrapped
in 29 turns around 15" of 6" inner pipe, with black stove cement for glue
and wire mesh over the outside to help keep the cement from cracking off.

Nick
 
B

Bruce in Alaska

Jan 1, 1970
0
Gordon Reeder said:
A couple of turns of copper tubing around your stove pipe/
chiminy pipe might work.

Actually, I designed a system to produce hot water from a wood burning
stove, and installed it at my guest cabin. I had a piece of 1/2" copper
tubing formed into a 6" outside diameter spiral coil with about 6 turns.
I then silver solderd on a 90 elbow on each end and a 6" nipple to that.
Then I took a 24" piece of 6" stovepipe, and cut two 1/2" holes for the
nipples to exit thru, while the stove pipe was laid out flat. I then
wrapped the stove pipe around the copper coil and reseamed the vertical
joint in the sheetmetal. I then installed this section directly above
the woodstove chimmney outlet, and the damper Flapper section directly
above it in the stove pipe. The coil is connected to a 35 Gallon Galv.
water tank, using the standard Thermalsyphon connections.
This system works very well for supplying hot water for this small one
room 16'X24" cabin. You have plenty of hot water after each cooking
session using the stove, and will provide reasonably warm water whilethe
stove is being used to heat the cabin.


Bruce in alaska
 
B

bw

Jan 1, 1970
0
Bruce in Alaska said:
Actually, I designed a system to produce hot water from a wood burning
stove, and installed it at my guest cabin. I had a piece of 1/2" copper
tubing formed into a 6" outside diameter spiral coil with about 6 turns.
I then silver solderd on a 90 elbow on each end and a 6" nipple to that.
Then I took a 24" piece of 6" stovepipe, and cut two 1/2" holes for the
nipples to exit thru, while the stove pipe was laid out flat. I then
wrapped the stove pipe around the copper coil and reseamed the vertical
joint in the sheetmetal. I then installed this section directly above
the woodstove chimmney outlet, and the damper Flapper section directly
above it in the stove pipe. The coil is connected to a 35 Gallon Galv.
water tank, using the standard Thermalsyphon connections.
This system works very well for supplying hot water for this small one
room 16'X24" cabin. You have plenty of hot water after each cooking
session using the stove, and will provide reasonably warm water whilethe
stove is being used to heat the cabin.


Bruce in alaska
--

Very nice, you put the coil inside the stove pipe. Did you put any
insulation around the heat exchanger? any insulation on the tubing?
How far apart are the coil turns from each other? An inch?
Approx how far above the coil is your receiver tank?
 
B

Bruce in Alaska

Jan 1, 1970
0
Very nice, you put the coil inside the stove pipe. Did you put any
insulation around the heat exchanger? any insulation on the tubing?
How far apart are the coil turns from each other? An inch?
Approx how far above the coil is your receiver tank?

The coils are uninsulated, and just reside inside the 6" stovepipe.
No insulation anywhere. Pitch of the coil is around 1.5" vertical
per turn. The tank bottom is at the same level as the top of the stove.
The cold water thermalsyphan port is about 6" lower than the bottom
connection on the coil. The hot water thermalsyphan port is about 6"
from the top of the tank. The tank has a drain on the bottom and a
Relief Valve on the top. The cold water entrance is jusat above the
drain valve, and the hot water outlet is just below the Relief Valve.
All this sits inside the cabins, super insulated structure, so there is
no need for any insulation, as the heat coming off the system is just
heating up the inside of the cabin and all BTU's come from the wood
stove anyway.

Bruce in alaska
 
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