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what is the use of the water cooling in this honda generator? - Page 3

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Posted by harry on October 30, 2009, 7:15 pm

Well, you'd recover something but you'd be better if you could make up
something out of stainless steel. The silencer/muffler is best
dispensed with & the heat X substituted for it.  This is standard
practice in Combined Heat & Power setups.
The problem is that acidic water condenses out in the exhaust which
rots away most things including copper.  If you wrapped a copper pie
round the exhaust, you'd probably fing the steel exhaust pipe rotting
away due to condensation.

Posted by Bruce in alaska on October 30, 2009, 7:50 pm

I use Marine type Water Jacketed Exhaust Manifolds to recover Exhaust
BTU's on my Gensets. I have also built Domestic Hot Water Heating
Systems for Wood and Oil Fired Stoves, by putting a 1/2 Soft Copper
Tubing Coil of maybe 5 or 6 Turns, inside a section of 6" Stove Pipe,
and using Woodstove Door Gasket Rope to seal up where the Inlet and
Outlet pipes come out of the Stove pipe. This then feeds a Thermalsyphan
System with a 55 USG Storage Tank in the Hot Water line for a cabin.
Works well if the Wood or Oil Fired Stove is the Main Heat for the cabin,
since it is always going. Then you always have HOT WATER, for the Little
Lady of the House. They can never have enough Hot Water.

Bruce in alaska
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Posted by Mike Romain on October 31, 2009, 6:19 pm

Bruce in alaska wrote:

I will look into the water jacketed exhaust as my Onan does have a
marine version and the muffler isn't set up properly right now anyway.
It has no brace on one end so it cracks the manifold from vibration and
is under a warranty, maybe the builder will do a swap.

I have also built Domestic Hot Water Heating

Nice, I want to take hot water off my wood stove also which is the
primary heat source for the cabin and was wondering about wrapping the
copper outside or inside the pipe.  I want to use convection to
circulate it also.  Do you have any drawings or photos of your design?


Posted by Bruce in alaska on October 31, 2009, 7:15 pm

What I did was make up the Copper Tubing Coil by packing the tube with
sand, and then bending it around a wood mandrel that was turned down, so
as to have the Outside diameter of the coil at 5 - 15/16ths inches. Once
the bending is done, (the sand keeps the tubing from kinking during the
bending process) I remove the sand, and wash out the tubing with water.
Then I silver soldered a 90 degree elbow on each end to bring the water
out thru the Stainless Stovepipe. Now that I have the coil built, I take
my section of Stovepipe, and break the seam, so I can roll it out flat,
and measure where to put the two holes for the Pipes to come thru, I
then used a 1/2" Greeley Punch to make the hole just slightly larger
than the Copper Pipe elbows, and install the coil, with elbows thru the
holes using the Woodstove Gasket Rope to make an exhaust tight fitting.
Then I reroll the Stovepipe around the coil, and reset the Seam top to
bottom. I then silver soldered two 3" pieces of tubing, with Copper
Unions on the other end, to the other outside ends of the elbows, so
that I could disconnect the water system from the Stack Coil when
Service, or Stovepipe Cleaning (which I do annually) is required. On the
other side Copper Unions I have Ball Valves, so I can isolate the Water
system, without draining it, during Servicing. I usually try to place
this section of Stovepipe as close to the stove as possible, so that it
has access to the most BTU's in the flue.

Sorry no pictures, and I have never CADDed this setup. I guess I should,
do that one of these days..... but I can tell you it works just fine,
and Momma really likes the running Hot Water.....

Bruce in alaska
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Posted by Mike Romain on October 31, 2009, 9:07 pm

Bruce in alaska wrote:

Excellent, I was hoping it would be that easy and works.  Our stove has
one horizontal section that should be good to collect heat.  My wife
also really likes running hot water too.

When I worked as a plumber last, we had coil springs that would fit over
the different sizes of soft copper pipe for bending which work great.  I
have also used fine sand which does the job nicely too.

How do you work the hot water tank feed?  I am figuring on having the
tank up one story above the stove and shower for a gravity feed.  I have
gravity feed coming to the cabin from a sweet brook that runs beside the
cabin.  Think 30' drop and microhydro come spring or maybe earlier.  :)

I was wondering the best way to have cold input or should I just have a
45-55 gallon tank circulating on the heat exchanger and fill it as needed?

Will convection move the water or does it need a small pump?

Does it get too hot I guess is one question or am I dreaming about how
many BTU's it transfers?


Off the grid in Canada

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