Possible chemistry question

After almost twenty (I think) years on this group, I know that it's
not a chemical or metallurgy forum, however with all the talented
people here I was hoping that someone could possibly offer a
suggestion for my problem, or perhaps refer me elsewhere.

For the past 35 years I have heated my home with a wood stove.
We are now on the third incarnation of wood stoves which we have
had. As they burn out we replace them. They have all been made
out of heavy gauge 55 gallon barrels, and I have been very satisfied
with all of them. There is a door for loading the wood in and an
output for smoke. It is a very simple, inexpensive and yet completely
passive but effective scenario.

Standing behind the stove for the last 30 or so years and again, in
keeping with the idea of simple and passive has been a 42 gallon
galvanized water tank. My first two tanks have sported a dull grey
finish.

The first tank was replaced about twenty years ago, and last Fall it
was necessary the replace the second tank. This will now be the third
tank since we've lived here. The new tank I purchased was equivalent
to the last two we've had, and it was installed directly in place of
the old one.This one however has a shiny metal finish.

Cold water runs into this tank and is heated by the stove. As the
electric hot water heater calls for water it is supplied by this tank.
Since the water is preheated, this has saved us thousands of
dollars over the years.

From the very beginning of the season I started to notice that the
new tank failed to get as hot as the older tanks did. In fact on the
coldest days even with the wood stove cranking, the new galvanized
tank barely would get hot at all. The best I ever noticed when putting
my hand on it was tepid, but never hot, as the old tanks would get.

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

It has been suggested that while a dull finish absorbs heat, a shiny
surface would reflect it, and so to make it perform as the last two did
I have to find a way to dull the surface of this tank.

I have thought about possibly painting this new tank with a flat paint.
Because it's indoors, this must be done with a brush, and during the
warm weather months so as to air out the house. I am however finding
out that flat high temperature paint, especially paint that that can
be used on galvanized surfaces is very difficult to find. Rutland
makes what would seem like an ideal high temperature flat black product
for wood stoves, however they do not recommend it's use on galvanized
surfaces. And truthfully I don't even know if painting the surface
with flat paint would even accomplish what I need to have happen.

My other thought, and a preferable one would be to find some way to
dull the existing finish to make this new tank comparable to the old
ones. I wonder if this could be done with some type of acid, like
muriatic perhaps?

I've really run into a wall here and I would sincerely appreciate any
thoughts on this matter and how it might be remedied. Thanks to all very
much for any information which you may be able to offer.

Lenny

I found this Web page on the galvanization process, but it doesn't
really help me:

http://www.google.com/url?q=http%3A%2F%2Fwww.galvanizeit.org%2Finspection-course%2Ftypes-of-inspection%2Ffinish-and-appearance%2Fdifferent-appearances&sa=D&sntz=1&usg=AFQjCNFzvuxoxyDJr81E9wnLxfLobTS_Qg

 

On Monday, May 18, 2015 at 4:14:46 AM UTC-4, captainvi...@gmail.com wrote:

After almost twenty (I think) years on this group, I know that it's
not a chemical or metallurgy forum, however with all the talented
people here I was hoping that someone could possibly offer a
suggestion for my problem, or perhaps refer me elsewhere.

For the past 35 years I have heated my home with a wood stove.
We are now on the third incarnation of wood stoves which we have
had. As they burn out we replace them. They have all been made
out of heavy gauge 55 gallon barrels, and I have been very satisfied
with all of them. There is a door for loading the wood in and an
output for smoke. It is a very simple, inexpensive and yet completely
passive but effective scenario.

Standing behind the stove for the last 30 or so years and again, in
keeping with the idea of simple and passive has been a 42 gallon
galvanized water tank. My first two tanks have sported a dull grey
finish.

The first tank was replaced about twenty years ago, and last Fall it
was necessary the replace the second tank. This will now be the third
tank since we've lived here. The new tank I purchased was equivalent
to the last two we've had, and it was installed directly in place of
the old one.This one however has a shiny metal finish.

Cold water runs into this tank and is heated by the stove. As the
electric hot water heater calls for water it is supplied by this tank.
Since the water is preheated, this has saved us thousands of
dollars over the years.

From the very beginning of the season I started to notice that the
new tank failed to get as hot as the older tanks did. In fact on the
coldest days even with the wood stove cranking, the new galvanized
tank barely would get hot at all. The best I ever noticed when putting
my hand on it was tepid, but never hot, as the old tanks would get.

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

It has been suggested that while a dull finish absorbs heat, a shiny
surface would reflect it, and so to make it perform as the last two did
I have to find a way to dull the surface of this tank.

I have thought about possibly painting this new tank with a flat paint.
Because it's indoors, this must be done with a brush, and during the
warm weather months so as to air out the house. I am however finding
out that flat high temperature paint, especially paint that that can
be used on galvanized surfaces is very difficult to find. Rutland
makes what would seem like an ideal high temperature flat black product
for wood stoves, however they do not recommend it's use on galvanized
surfaces. And truthfully I don't even know if painting the surface
with flat paint would even accomplish what I need to have happen.

My other thought, and a preferable one would be to find some way to
dull the existing finish to make this new tank comparable to the old
ones. I wonder if this could be done with some type of acid, like
muriatic perhaps?

I've really run into a wall here and I would sincerely appreciate any
thoughts on this matter and how it might be remedied. Thanks to all very
much for any information which you may be able to offer.

Lenny

I found this Web page on the galvanization process, but it doesn't
really help me:

http://www.google.com/url?q=http%3A%2F%2Fwww.galvanizeit.org%2Finspection-course%2Ftypes-of-inspection%2Ffinish-and-appearance%2Fdifferent-appearances&sa=D&sntz=1&usg=AFQjCNFzvuxoxyDJr81E9wnLxfLobTS_Qg

The only way the cold water tank is heated is by radiation?
No pieces of metal or water lines connecting the two?
If so, then yes you have an emissivity problem.
http://en.wikipedia.org/wiki/Emissivity

How to fix it, I'm not so sure. Black oxide finish?

George H.

 

[Tim R]

I am not convinced radiation is the problem.

You've replaced two components, a stove and a tank.

You're focusing on the finish of the tank, but that may be premature.

Is the stove the same dimension? Same distance from the tank? Same thickness metal and runs at the same temperature?

Maybe the tank is anchored different? It was formerly in contact with some common metal bracket, and got most of its heat through conduction?

 

[Baron]

captainvideo462009@gmail.com prodded the keyboard with:

After almost twenty (I think) years on this group, I know that it's
not a chemical or metallurgy forum, however with all the talented
people here I was hoping that someone could possibly offer a
suggestion for my problem, or perhaps refer me elsewhere.

For the past 35 years I have heated my home with a wood stove.
We are now on the third incarnation of wood stoves which we have
had. As they burn out we replace them. They have all been made
out of heavy gauge 55 gallon barrels, and I have been very satisfied
with all of them. There is a door for loading the wood in and an
output for smoke. It is a very simple, inexpensive and yet
completely passive but effective scenario.

Standing behind the stove for the last 30 or so years and again, in
keeping with the idea of simple and passive has been a 42 gallon
galvanized water tank. My first two tanks have sported a dull grey
finish.

The first tank was replaced about twenty years ago, and last Fall it
was necessary the replace the second tank. This will now be the
third tank since we've lived here. The new tank I purchased was
equivalent to the last two we've had, and it was installed directly
in place of the old one.This one however has a shiny metal finish.

Cold water runs into this tank and is heated by the stove. As the
electric hot water heater calls for water it is supplied by this
tank. Since the water is preheated, this has saved us thousands of
dollars over the years.

From the very beginning of the season I started to notice that the
new tank failed to get as hot as the older tanks did. In fact on the
coldest days even with the wood stove cranking, the new galvanized
tank barely would get hot at all. The best I ever noticed when
putting my hand on it was tepid, but never hot, as the old tanks
would get.

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while
the new tank has a grey shiny metal finish.

It has been suggested that while a dull finish absorbs heat, a shiny
surface would reflect it, and so to make it perform as the last two
did I have to find a way to dull the surface of this tank.

I have thought about possibly painting this new tank with a flat
paint. Because it's indoors, this must be done with a brush, and
during the warm weather months so as to air out the house. I am
however finding out that flat high temperature paint, especially
paint that that can be used on galvanized surfaces is very difficult
to find. Rutland makes what would seem like an ideal high
temperature flat black product for wood stoves, however they do not
recommend it's use on galvanized surfaces. And truthfully I don't
even know if painting the surface with flat paint would even
accomplish what I need to have happen.

My other thought, and a preferable one would be to find some way to
dull the existing finish to make this new tank comparable to the old
ones. I wonder if this could be done with some type of acid, like
muriatic perhaps?

I've really run into a wall here and I would sincerely appreciate
any thoughts on this matter and how it might be remedied. Thanks to
all very much for any information which you may be able to offer.

Lenny

I found this Web page on the galvanization process, but it doesn't
really help me:


http://www.google.com/url?q=http%3A%2F%2Fwww.galvanizeit.org%2Finspection-course%2Ftypes-of-inspection%2Ffinish-and-appearance%2Fdifferent-appearances&sa=D&sntz=1&usg=AFQjCNFzvuxoxyDJr81E9wnLxfLobTS_Qg

A coat of "Blackboard" black will cure that problem. A coat of PVA
first will help it stick and not flake with age.

--
Best Regards:
Baron.

 

[Jeff Liebermann]

On Mon, 18 May 2015 01:14:44 -0700 (PDT), captainvideo462009@gmail.com
wrote:

>For the past 35 years I have heated my home with a wood stove.

Same here for almost exactly the same time period. The first few
years were hell because I had no clue of what I was doing. I did
almost everything wrong.

We are now on the third incarnation of wood stoves which we have
had.

I'm on my 2nd which has lasted about 30 years:
<http://802.11junk.com/jeffl/pics/home/slides/wood-burner.html>
I'm on my 3rd replacement fire brick, 3rd asbestos door seal, and have
had to weld a few things back together that had "burnt" out. Note
that the door is warped and not making a good seal. I'm debating the
merits of straightening the door, replacing the door, or just buying
an approved and more efficient stove.

As they burn out we replace them. They have all been made
out of heavy gauge 55 gallon barrels, and I have been very satisfied
with all of them. There is a door for loading the wood in and an
output for smoke. It is a very simple, inexpensive and yet completely
passive but effective scenario.

Yeah, but there's almost no thermal mass in a barrel to keep the fire
going and to hold the heat inside. Such barrel stoves are very
economical to build, but not very economical to operate. If you're
going to build your own, get some kind of heavy welded steel box that
can be made air tight. Build a labyrinth for the smoke, so that the
hot air stays inside the stove longer. Attach an AIR TIGHT door.

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

The problem with your description and analysis is that it lacks
numbers. Some IR temperature measurements would be handy. Also some
photos. Personally, a painted black surface is probably best at
radiating the heat. That's if you want to heat the room, not keep the
heat inside, like a water heater. That's why wood burners are black,
and water heaters are white.

I don't think the surface color is going to make much difference. For
example, some of the best wood burning stoves from Jotul come in all
manner of colors (white, red, green, yellow, etc).

My guess(tm) is something else is happening. However, I can't offer
much advice on the something else without a photo and better
description. The approximate weight would also be useful. It's no
coincidence that the most efficient stoves are monstrous masonry
affairs with a huge thermal mass. Also, some clue as to the flue
system and how much of it is insulated pipe (Metalbestos or triple
wall).

In the few stoves that I've worked on (mostly fixing my own mistakes),
the efficiency is mostly the quality of the firewood, the mass of the
stove, and a well controlled air flow.

I don't know of any forums or newsgroups that specialize in wood
burning water heaters. Incidentally, I've helped build three wood
burning hot tubs. They're quite economical to operate but does
require some care in siteing, construction, and operation. My
favorite mistake was placing the chimney upwind of the tub. It worked
well if you wore a gas mask.

Good luck.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Mon, 18 May 2015 09:09:20 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

If you think shiney wood burning water heaters don't work, take a look
at these made from stainless steel:
<http://www.cedartubs.com/wood-fired-hot-tub-heaters.html>
<http://www.woodwaterstoves.com/external-heaters.html>

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Bennett]

From the way you describe the water tank it sounds like the
surface never gets really hot - its filled with cold water and
isn't touching the stove. Maybe you don't need a special high
temperature paint - just plain old black in a spray can.

On 5/18/2015 1:14 AM, captainvideo462009@gmail.com wrote:

After almost twenty (I think) years on this group, I know that it's
not a chemical or metallurgy forum, however with all the talented
people here I was hoping that someone could possibly offer a
suggestion for my problem, or perhaps refer me elsewhere.

For the past 35 years I have heated my home with a wood stove.
We are now on the third incarnation of wood stoves which we have
had. As they burn out we replace them. They have all been made
out of heavy gauge 55 gallon barrels, and I have been very satisfied
with all of them. There is a door for loading the wood in and an
output for smoke. It is a very simple, inexpensive and yet completely
passive but effective scenario.

Standing behind the stove for the last 30 or so years and again, in
keeping with the idea of simple and passive has been a 42 gallon
galvanized water tank. My first two tanks have sported a dull grey
finish.

The first tank was replaced about twenty years ago, and last Fall it
was necessary the replace the second tank. This will now be the third
tank since we've lived here. The new tank I purchased was equivalent
to the last two we've had, and it was installed directly in place of
the old one.This one however has a shiny metal finish.

Cold water runs into this tank and is heated by the stove. As the
electric hot water heater calls for water it is supplied by this tank.
Since the water is preheated, this has saved us thousands of
dollars over the years.

From the very beginning of the season I started to notice that the
new tank failed to get as hot as the older tanks did. In fact on the
coldest days even with the wood stove cranking, the new galvanized
tank barely would get hot at all. The best I ever noticed when putting
my hand on it was tepid, but never hot, as the old tanks would get.

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

It has been suggested that while a dull finish absorbs heat, a shiny
surface would reflect it, and so to make it perform as the last two did
I have to find a way to dull the surface of this tank.

I have thought about possibly painting this new tank with a flat paint.
Because it's indoors, this must be done with a brush, and during the
warm weather months so as to air out the house. I am however finding
out that flat high temperature paint, especially paint that that can
be used on galvanized surfaces is very difficult to find. Rutland
makes what would seem like an ideal high temperature flat black product
for wood stoves, however they do not recommend it's use on galvanized
surfaces. And truthfully I don't even know if painting the surface
with flat paint would even accomplish what I need to have happen.

My other thought, and a preferable one would be to find some way to
dull the existing finish to make this new tank comparable to the old
ones. I wonder if this could be done with some type of acid, like
muriatic perhaps?

I've really run into a wall here and I would sincerely appreciate any
thoughts on this matter and how it might be remedied. Thanks to all very
much for any information which you may be able to offer.

Lenny

I found this Web page on the galvanization process, but it doesn't
really help me:

http://www.google.com/url?q=http%3A%2F%2Fwww.galvanizeit.org%2Finspection-course%2Ftypes-of-inspection%2Ffinish-and-appearance%2Fdifferent-appearances&sa=D&sntz=1&usg=AFQjCNFzvuxoxyDJr81E9wnLxfLobTS_Qg

 

[Bob F]

Jeff Liebermann wrote:

On Mon, 18 May 2015 09:09:20 -0700, Jeff Liebermann <jeffl@cruzio.com
wrote:

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while
the new tank has a grey shiny metal finish.

If you think shiney wood burning water heaters don't work, take a look
at these made from stainless steel:
http://www.cedartubs.com/wood-fired-hot-tub-heaters.html
http://www.woodwaterstoves.com/external-heaters.html

There's a big difference between condustance to water and radiance through air
to another metal surface. Compare the temperatures of a black and a mirrored
sheet of metal sitting in the hot summer sun. Or a black car to a white car.

I'd recommend painting the stove side of the water tank with a thin coat of
black, and leave the rest shiny. Paint is an insulator too, so a thick coat will
not help.

 

[Tim R]

On Monday, May 18, 2015 at 5:28:25 PM UTC-4, Bob F wrote:

I'd recommend painting the stove side of the water tank with a thin coat of
black, and leave the rest shiny. Paint is an insulator too, so a thick coat will
not help.

First I'd recommend measuring the distance between the stove and the tank, and measuring the temperature of the surface of the stove - assuming a radiant heat transfer only, which I still am somewhat skeptical of.

 

On Monday, May 18, 2015 at 12:19:42 PM UTC-4, Jeff Liebermann wrote:

On Mon, 18 May 2015 09:09:20 -0700, Jeff Liebermann <jeffl@cruzio.com
wrote:

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

If you think shiney wood burning water heaters don't work, take a look
at these made from stainless steel:
http://www.cedartubs.com/wood-fired-hot-tub-heaters.html
http://www.woodwaterstoves.com/external-heaters.html

Hi Jeff, You want those shinny. (Less heat loss to the surroundings.)
I assume there is a water jacket around the stove and
water flowing through it from the hot tub.

George H.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[John-Del]

On Monday, May 18, 2015 at 10:22:45 PM UTC-4, Tim R wrote:

On Monday, May 18, 2015 at 5:28:25 PM UTC-4, Bob F wrote:
I'd recommend painting the stove side of the water tank with a thin coat of
black, and leave the rest shiny. Paint is an insulator too, so a thick coat will
not help.

First I'd recommend measuring the distance between the stove and the tank, and measuring the temperature of the surface of the stove - assuming a radiant heat transfer only, which I still am somewhat skeptical of.

He's not heating water this way for domestic use, he's just using this arrangement to preheat the inlet water to his electric hot water heater. If it didn't work at all, he'd still have normal hot water.

I agree that a thin coat of flat black paint would probably be the best solution. I also wonder if building a small enclosure around it to trap some heated air in order to pick up some heat by conduction wouldn't help.

 

[John-Del]

On Tuesday, May 19, 2015 at 3:07:43 PM UTC-4, Jeff Liebermann wrote:

On Tue, 19 May 2015 10:33:21 -0700 (PDT), John-Del <ohger1s@aol.com
wrote:

I agree that a thin coat of flat black paint would probably be the best solution.

I beg to differ. What the black paint does is improve the radiation
efficiency of the box. That's not what he needs. In order to heat
the water jacket, which is inside the steel box, he needs to keep the
heat inside the box, not radiate it away to heat the air or nearby
objects. Ideally, the outside of the box should be wrapped in
insulation to keep the head inside the box, like a water heater. If
you want to keep the heat in, he should use a white or reflective
outer surface, which does not radiate very well.


--

Jeff, reread the OP's post. I've quoted it but edited it for clarity:

"Standing behind the stove for the last 30 or so years and again, in
keeping with the idea of simple and passive has been a 42 gallon
galvanized water tank. My first two tanks have sported a dull grey
finish. This one (the new tank) however has a shiny metal finish.
Cold water runs into this tank and is heated by the stove. As the
electric hot water heater calls for water it is supplied by this tank."

What I get from this is that he has a water tank near his wood stove that picks up heat with no direct connection. Most of the water in the tank is heated by radiation and whatever conduction it can pick up from warm air around it.

If his new tank is reflective in finish, it will reflect a lot of the radiated heat instead of absorbing it, no?

 

[Tim R]

On Tuesday, May 19, 2015 at 4:16:33 PM UTC-4, John-Del wrote:

What I get from this is that he has a water tank near his wood stove that picks up heat with no direct connection. Most of the water in the tank is heated by radiation and whatever conduction it can pick up from warm air around it.

If his new tank is reflective in finish, it will reflect a lot of the radiated heat instead of absorbing it, no?

Maybe so, maybe no. We don't know for sure this is a radiant heating condition. We also know not only the tank, but the stove has been changed out, and we don't know what changes occurred in the stove. It would be nice to see photos.

But in answer to your question, I ask another: reflect to where? If the stove and tank are close enough, and flat enough, radiation reduces to that between plane surfaces. r^2 no longer applies as it would to a point source, and r no longer applies as it would to a near field line source. r essentially disappears, and we have the case where everything reflected from the tank goes back to the stove, making it hotter, then transmitting back to the tank. I think color is probably a wash here.

 

[Jeff Liebermann]

On Tue, 19 May 2015 10:33:21 -0700 (PDT), John-Del <ohger1s@aol.com>
wrote:

>I agree that a thin coat of flat black paint would probably be the best solution.

I beg to differ. What the black paint does is improve the radiation
efficiency of the box. That's not what he needs. In order to heat
the water jacket, which is inside the steel box, he needs to keep the
heat inside the box, not radiate it away to heat the air or nearby
objects. Ideally, the outside of the box should be wrapped in
insulation to keep the head inside the box, like a water heater. If
you want to keep the heat in, he should use a white or reflective
outer surface, which does not radiate very well.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[John Robertson]

On 05/19/2015 1:56 PM, Tim R wrote:

On Tuesday, May 19, 2015 at 4:16:33 PM UTC-4, John-Del wrote:
What I get from this is that he has a water tank near his wood stove that picks up heat with no direct connection. Most of the water in the tank is heated by radiation and whatever conduction it can pick up from warm air around it.

If his new tank is reflective in finish, it will reflect a lot of the radiated heat instead of absorbing it, no?

Maybe so, maybe no. We don't know for sure this is a radiant heating condition. We also know not only the tank, but the stove has been changed out, and we don't know what changes occurred in the stove. It would be nice to see photos.

But in answer to your question, I ask another: reflect to where? If the stove and tank are close enough, and flat enough, radiation reduces to that between plane surfaces. r^2 no longer applies as it would to a point source, and r no longer applies as it would to a near field line source. r essentially disappears, and we have the case where everything reflected from the tank goes back to the stove, making it hotter, then transmitting back to the tank. I think color is probably a wash here.

Round tank (42 Gallon drum) so if reflective most of the heat will
bounce off walls, etc. not head back to the stove. Think convex mirror...

He could probably simply roughen the surface of the tank that faces the
stove and get a reasonable heating increase result, the roughened
surface being less reflective...

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

On Monday, May 18, 2015 at 4:14:46 AM UTC-4, captainvi...@gmail.com wrote:

After almost twenty (I think) years on this group, I know that it's
not a chemical or metallurgy forum, however with all the talented
people here I was hoping that someone could possibly offer a
suggestion for my problem, or perhaps refer me elsewhere.

For the past 35 years I have heated my home with a wood stove.
We are now on the third incarnation of wood stoves which we have
had. As they burn out we replace them. They have all been made
out of heavy gauge 55 gallon barrels, and I have been very satisfied
with all of them. There is a door for loading the wood in and an
output for smoke. It is a very simple, inexpensive and yet completely
passive but effective scenario.

Standing behind the stove for the last 30 or so years and again, in
keeping with the idea of simple and passive has been a 42 gallon
galvanized water tank. My first two tanks have sported a dull grey
finish.

The first tank was replaced about twenty years ago, and last Fall it
was necessary the replace the second tank. This will now be the third
tank since we've lived here. The new tank I purchased was equivalent
to the last two we've had, and it was installed directly in place of
the old one.This one however has a shiny metal finish.

Cold water runs into this tank and is heated by the stove. As the
electric hot water heater calls for water it is supplied by this tank.
Since the water is preheated, this has saved us thousands of
dollars over the years.

From the very beginning of the season I started to notice that the
new tank failed to get as hot as the older tanks did. In fact on the
coldest days even with the wood stove cranking, the new galvanized
tank barely would get hot at all. The best I ever noticed when putting
my hand on it was tepid, but never hot, as the old tanks would get.

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

It has been suggested that while a dull finish absorbs heat, a shiny
surface would reflect it, and so to make it perform as the last two did
I have to find a way to dull the surface of this tank.

I have thought about possibly painting this new tank with a flat paint.
Because it's indoors, this must be done with a brush, and during the
warm weather months so as to air out the house. I am however finding
out that flat high temperature paint, especially paint that that can
be used on galvanized surfaces is very difficult to find. Rutland
makes what would seem like an ideal high temperature flat black product
for wood stoves, however they do not recommend it's use on galvanized
surfaces. And truthfully I don't even know if painting the surface
with flat paint would even accomplish what I need to have happen.

My other thought, and a preferable one would be to find some way to
dull the existing finish to make this new tank comparable to the old
ones. I wonder if this could be done with some type of acid, like
muriatic perhaps?

I've really run into a wall here and I would sincerely appreciate any
thoughts on this matter and how it might be remedied. Thanks to all very
much for any information which you may be able to offer.

Lenny

I found this Web page on the galvanization process, but it doesn't
really help me:

http://www.google.com/url?q=http%3A%2F%2Fwww.galvanizeit.org%2Finspection-course%2Ftypes-of-inspection%2Ffinish-and-appearance%2Fdifferent-appearances&sa=D&sntz=1&usg=AFQjCNFzvuxoxyDJr81E9wnLxfLobTS_Qg

I did actually think about taking a belt sander to the new tank but I wasn't too wild about having powdered galvanized material floating around. Dulling the finish would however restore all previous conditions to where they were with the old tank. Lenny

 

[Jeff Liebermann]

On Tue, 19 May 2015 05:03:11 -0700 (PDT), ggherold@gmail.com wrote:

On Monday, May 18, 2015 at 12:19:42 PM UTC-4, Jeff Liebermann wrote:
On Mon, 18 May 2015 09:09:20 -0700, Jeff Liebermann <jeffl@cruzio.com
wrote:

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

If you think shiney wood burning water heaters don't work, take a look
at these made from stainless steel:
http://www.cedartubs.com/wood-fired-hot-tub-heaters.html
http://www.woodwaterstoves.com/external-heaters.html

Hi Jeff, You want those shinny. (Less heat loss to the surroundings.)
I assume there is a water jacket around the stove and
water flowing through it from the hot tub.

George H.

That's also what I assumed. However, it was pointed out that this is
not the case. There are two tanks. One has a fire inside. The other
is full of water. Nothing but air in between. The distances and
measurements are unknown. In effect, it's radiation heating which at
the presumed distance, is not terribly efficient.

I still think the stainless hot tub heaters are cool looking (and
probably rather expensive). I want one.

The three wood burning hot tub heaters that I built were essentially
open air boilers. Basically, a rectangular box made from firebrick.
One end has an air tight cast iron stove door. The other has a
chimney made from flue pipe. On top was a sheet of copper, steel
plate, or stainless steel, depending on the model. 2x12 redwood on
top of the metal plate to act as a water tank. A wood grating in the
tank to keep the feet from getting scorched. I would build a fire
underneath that would heat the metal bottom, which would heat the
water in the tank. Temperature was regulated by a nearby cold water
hose. The first time I fired it up, I had boiling water in about 30
mins. Oops. If I was in a hurry, I would get some coals going in the
wood burner, and then move then quickly to the hot tub heater. All
three leaked on the outside (but not into the firebox). I kinda miss
it.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Tue, 19 May 2015 13:16:30 -0700 (PDT), John-Del <ohger1s@aol.com>
wrote:

On Tuesday, May 19, 2015 at 3:07:43 PM UTC-4, Jeff Liebermann wrote:
On Tue, 19 May 2015 10:33:21 -0700 (PDT), John-Del <ohger1s@aol.com
wrote:

I agree that a thin coat of flat black paint would probably be the best solution.

I beg to differ. What the black paint does is improve the radiation
efficiency of the box. That's not what he needs. In order to heat
the water jacket, which is inside the steel box, he needs to keep the
heat inside the box, not radiate it away to heat the air or nearby
objects. Ideally, the outside of the box should be wrapped in
insulation to keep the head inside the box, like a water heater. If
you want to keep the heat in, he should use a white or reflective
outer surface, which does not radiate very well.


Jeff, reread the OP's post. I've quoted it but edited it for clarity:

"Standing behind the stove for the last 30 or so years and again, in
keeping with the idea of simple and passive has been a 42 gallon
galvanized water tank. My first two tanks have sported a dull grey
finish. This one (the new tank) however has a shiny metal finish.
Cold water runs into this tank and is heated by the stove. As the
electric hot water heater calls for water it is supplied by this tank."

Oops. I missed that the tank was next to the stove. I just assumed
that he was doing it in the conventional manner, using either a water
jacket or serpentine copper hose arrangement. Something like the wood
burning hot tub stove I previously mentioned. He's doing radiation
heating which at the presumed distance between the stove and tank is
rather inefficient.

<https://www.google.com/search?q=wood+burning+water+heater&tbm=isch>
Hmmm... I don't see any that utilize external radiation heating.

What I get from this is that he has a water tank near his wood stove
that picks up heat with no direct connection. Most of the water in
the tank is heated by radiation and whatever conduction it can pick
up from warm air around it.

If his new tank is reflective in finish, it will reflect a lot of
the radiated heat instead of absorbing it, no?

Right. That means the proper color for the tank would be black so as
to absorb as much heat as possible on the surface, which would
eventually conduct to the water through the galvanized water tank. The
proper color for the stove would also be black, for the same reason.
I think an IR thermometer and a photo will settle the matter.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Tim R]

On Wednesday, May 20, 2015 at 1:18:04 AM UTC-4, Jeff Liebermann wrote:

Oops. I missed that the tank was next to the stove. I just assumed
that he was doing it in the conventional manner, using either a water
jacket or serpentine copper hose arrangement. Something like the wood
burning hot tub stove I previously mentioned. He's doing radiation
heating which at the presumed distance between the stove and tank is
rather inefficient.

I think extremely inefficient.

I can't imagine doing it that way.

Here's a thought: can we add conduction heat transfer to the current radiation transfer? (a photo would be nice, I'm suspicious more has been changed than just the color. I bet the new stove is a different shape and farther away, or some other change) How about bolting a couple of copper straps to each tank? Leave a loop in them for expansion/contraction. You could improve heat transfer by orders of magnitude that way.

 

On Monday, May 18, 2015 at 4:14:46 AM UTC-4, captainvi...@gmail.com wrote:

After almost twenty (I think) years on this group, I know that it's
not a chemical or metallurgy forum, however with all the talented
people here I was hoping that someone could possibly offer a
suggestion for my problem, or perhaps refer me elsewhere.

For the past 35 years I have heated my home with a wood stove.
We are now on the third incarnation of wood stoves which we have
had. As they burn out we replace them. They have all been made
out of heavy gauge 55 gallon barrels, and I have been very satisfied
with all of them. There is a door for loading the wood in and an
output for smoke. It is a very simple, inexpensive and yet completely
passive but effective scenario.

Standing behind the stove for the last 30 or so years and again, in
keeping with the idea of simple and passive has been a 42 gallon
galvanized water tank. My first two tanks have sported a dull grey
finish.

The first tank was replaced about twenty years ago, and last Fall it
was necessary the replace the second tank. This will now be the third
tank since we've lived here. The new tank I purchased was equivalent
to the last two we've had, and it was installed directly in place of
the old one.This one however has a shiny metal finish.

Cold water runs into this tank and is heated by the stove. As the
electric hot water heater calls for water it is supplied by this tank.
Since the water is preheated, this has saved us thousands of
dollars over the years.

From the very beginning of the season I started to notice that the
new tank failed to get as hot as the older tanks did. In fact on the
coldest days even with the wood stove cranking, the new galvanized
tank barely would get hot at all. The best I ever noticed when putting
my hand on it was tepid, but never hot, as the old tanks would get.

I have wracked my brain trying to figure out what could possibly be
going on here, and the only thing I could come up with is the fact
that the first two old tanks had a dull grey finish to them, while the
new tank has a grey shiny metal finish.

It has been suggested that while a dull finish absorbs heat, a shiny
surface would reflect it, and so to make it perform as the last two did
I have to find a way to dull the surface of this tank.

I have thought about possibly painting this new tank with a flat paint.
Because it's indoors, this must be done with a brush, and during the
warm weather months so as to air out the house. I am however finding
out that flat high temperature paint, especially paint that that can
be used on galvanized surfaces is very difficult to find. Rutland
makes what would seem like an ideal high temperature flat black product
for wood stoves, however they do not recommend it's use on galvanized
surfaces. And truthfully I don't even know if painting the surface
with flat paint would even accomplish what I need to have happen.

My other thought, and a preferable one would be to find some way to
dull the existing finish to make this new tank comparable to the old
ones. I wonder if this could be done with some type of acid, like
muriatic perhaps?

I've really run into a wall here and I would sincerely appreciate any
thoughts on this matter and how it might be remedied. Thanks to all very
much for any information which you may be able to offer.

Lenny

I found this Web page on the galvanization process, but it doesn't
really help me:

http://www.google.com/url?q=http%3A%2F%2Fwww.galvanizeit.org%2Finspection-course%2Ftypes-of-inspection%2Ffinish-and-appearance%2Fdifferent-appearances&sa=D&sntz=1&usg=AFQjCNFzvuxoxyDJr81E9wnLxfLobTS_Qg

I found this picture in the link below of a similar installation. It's not a very good picture but I think you can get the idea. The water tank looks a bit taller than mine, (and it looks to be dull grey). Mine stands 53 inches and is 15 inches in diameter. The exact size of his tank is hard to tell from the picture. My tank stands right behind the stove and touches it as this one appears to. My system of course is in the basement, and with the exception that I'm using a barrel for the stove this is essentially what I'm doing. I knew at the time I built this contraption that I could have run copper coils around the flue or the stove, or inside of the stove for that matter, add circulating pumps, and perhaps any or all of these might have yielded a more efficient water heating scenario. However I really wanted to keep it simple. And it has been and has worked flawlessly all these years.

The other thing is here in Hew Hampshire we frequently lose power. When that happens in the Winter it's long and drawn out and most people have to go to a shelter. For us though the transition is pretty seamless. We automatically have heat, and we fire up the generator and we can even watch OTA TV if we want to. So at the expense of a little bit of efficiency I really don't want to fix, or change the basic concept of this (as they say), "if it ain't broke".

http://www.redwoodhikes.com/SequoiaNP/BearpawMore.html

This latest stove was made out of a heavy gauge 55 gallon galvanized
drum.Galvanized was not my choice because it wasn't necessary, but the
drum was pristine, the heavy gauge I wanted was available, and the
price was right. The finish was flat, and after this heating season
most of the galvanized coating has flaked off anyway. So it is
essentially a flat finish drum. That seems fine to me.

A little bit about the installation. The output flue pipe comes out of
the top rear of the stove. It goes up about four feet and makes a 90
degree turn and travels back about another five feet to where it
connects to the wall. About three feet above the stove before I make the 90 degree turn I have installed a damper. I start the stove with the damper open, however
I'm careful to not run wide open once it gets going as this stove
radiates a lot of heat.

There are times, few, but they do sometimes occur (if I'm not careful
to close the flue down sufficiently) that certain small areas of the
stove may get cherry red. I don't know what temperature that might be,
but I'm assuming that it would burn off any paint that might be on it,
high temperature rated or not. So for that reason I've never painted
any of my stoves.

My first stove was made out of a 55 gallon galvanized hazardous waste
container and lasted about ten years. The last stove was made from a
55 gallon stainless steel barrel. It was unpainted and it lasted for
almost twenty years. The combination of it and the flat galvanized
finish on the old water tank was very successful. So it probably would
not be practical for me to paint my current stove, but as it's been
suggested here I will paint the water tank.

Another friend to whom I've been talking to about this has suggested that there are primers available for painting galvanized (or zinc plated) steel. Once primed, I can use any flat black paint on the water tank. He also mentioned that high temperature paint is only needed on the wood stove drum. "The water tank can use most any flat black paint because the thermal mass of the water tank and the water inside prevents the surface temperature from rising more than a couple of degrees above the contents". (This is a quote). Most of you guys know a lot more about this than I do.

It would be nice to spray this primer and flat paint on to the tank but I can't because it's indoors I can't control the mist and over spray. So I need to start looking around for a suitable primer and flat paint, (both brush on) that would work on galvanized metal.

I really appreciate any further thoughts anyone may have on this. Does anyone know of any suitable paint and primer suitable for this application, particularly a brush on primer that will adhere to galvanized
metal? Thanks, Lenny