Galvanized tank as a pre-heater?

[neverrude]

I just got a new 40gal galvanized well tank to put next to the Jotul to pre-heat the water before it goes into the hot water tank.

I just read on the side of the tank when I was prepping it for a primer coat that it’s for cold water storage only. Can I still use it as a pre-heater?

 

[Dune]

Zinc melts at 800 degrees F.

 

[Redox]

Depends on the definition of "cold". As long as you are not actively heating it with some kind of heat exchanger, you will be fine. Just setting it in a warm room isn't going to cause any problems as you probably aren't going to be able to get it over about 100F, unless you put the tank on top of the stove (NOT recommended!). I'd put a relief valve on it in case someone closed the valves in and out of the tank. A solid tank of water (with no air cushion) can generate a lot of pressure when it warms up. It's not likely to explode like a water heater, but might split something.

Condensation might be a concern, too. Maybe you can make up some kind of sheet metal pan to sit it in to catch any sweat that happens?

Chris

 

[neverrude]

I was thinking about keeping it about a 1ft away from the side of the 118.
Would that be to close or or what distance would you recommend?

 

[begreen]

Seems like a long shot, but I would think that in order to get some benefit it would need to be like an inch away from the stove side.

 

[Redox]

Seems like a long shot, but I would think that in order to get some benefit it would need to be like an inch away from the stove side.

I hate to disagree, but if you can raise your 55 degree well water up to 85 before it goes into your water heater, you will have done about half the work of the water heater and probably not noticed the difference in the room. Even just getting it up to room temperature will help. Our tap water (supplied by the city) runs down to 38 degrees in the winter making the potential savings even more pronounced.

Chris

 

[wellbuilt home]

A well pressure tank has a rubber liner that makes the pressure when the well pumps it up. It could melt .If it pops you could use it for wash water but i dont no about drinking. I think the tanks rust . I have been thinking about running copper pipe around my flue pipe and hooking it to the hot and cold supply on my water heater to warm the tank so i dont need to run propain .I think this will keep me in hot water .I dont no if it could blow up, the water tank has a pressure valve.

 

[Redox]

The bladder tanks like the X-trol have a pressurized shell and fill a balloon with water. They also only have one connection. A "contact tank" is used for water treatment and will have a connection top and bottom. This allows the whole tank to fill with water for maximum capacity, but won't develop pressure on its own. Most are galvanized inside and out and should last a while unless you have very aggressive water.

Chris

 

[begreen]

Seems like a long shot, but I would think that in order to get some benefit it would need to be like an inch away from the stove side.

I hate to disagree, but if you can raise your 55 degree well water up to 85 before it goes into your water heater, you will have done about half the work of the water heater and probably not noticed the difference in the room. Even just getting it up to room temperature will help. Our tap water (supplied by the city) runs down to 38 degrees in the winter making the potential savings even more pronounced.

Chris

That's a big if. Just saying it would probably take quite awhile for it to raise the tank up 30 degrees. I would expect it to take many hours >8. If someone needs hot water during that time and draws in some more cold water, I would be surprised if there was even a 5 degree rise. However, overnight, if the basement is kept hot, maybe it would raise the tank to room temp at a foot away. My point being, if I was going to try this experiment I would place the tank as close to the stove as possible in order to cut down the hours of heat transfer time.

(fwiw, depending on the source, winter water is often much colder. More like 40-45 at our house.)

 

[Redox]

Yes, that's an extreme example, but if it raises the temperature at all, it's working. Since the tank is probably pretty cheap and has no moving parts, I think it's worth a try. Closer would be better, but the paint and galvanizing would concern me at 1" clearance.

Chris

 

[neverrude]

The tank does not have a bladder in it and I’m using high temperature black paint.
It’s the same that's used for painting grills.

I read in another thread about someone using a hot water tank for the same purpose.

Now I’m wondering if I should return the tank and get a cheap hot water tank and remove the insulation. :-S

 

[drizler]

My neighbor has a sweet rig in his place put in no doubt by an old plumber he knows. He has a 40 gallon hot water tank hanging right over his stove in the basement. Its against a brick wall and has 2 sides blocked in by a thin sheet metal wall with steel studding. Real sweet rig that preheats all the water going into his boiler. It is all painted black and works splendidly he says. This year I am going to do an exact copy using a perfect stainless tank I found that some guy put out 5 minutes before after converting to electric from his once supercell. That is exactly what I am going to do with mine this winter, hang that puppy right over the top of the Timberridge 50 I am ordering this week. Put on an expansion tank and safety valve and let it dump into the baseboards now heated by my almost useless oil boiler.
There is no reason any ordinary water tank wouldn't raise the temp up considerably sitting next to a wood stove. You could even devise a cheap plenum like my neighbor but on the side and not as high. Of course it won't look pretty but then pretty isn't what its all about in $4 gallon oil markets. Anything you can do to get that temp up some is going to be an appreciable gain. Of course you are going to want to get it up off the cement floor on something insulated to keep it from leaching out all your heat. BTW here in the Tundra my water pipe coming in from the well measures around 42F during the winter so even if you can get it up to 65 or 70 you will be gaining quite well. Don't forget you don't need 180 F water t shower. I have been running my supercell manually 3 seaasons of the year for 7 or 8 years utilizing the wall emergency switch. More recently I put in an indoor outdoor thermometer to watch the tank temp. Pretty easy to do, just cut the wire somewhere leaving enough to work at the end and make it extended using cheap speaker wire. Then you take that outdoor extended lead and run the sensor ( you should actually do that first ) down to the top of your tank. Stuff it in side the insulation or in the case of your exposed tank and stick the sensor onto the top and you are done. Then the outdoor temp is the temp of the water in the top of the tank. Not very scientific but it works very well except for over 145 in the case of mine it blanks out which is no big deal for me. I find that 117 F in the top of my 30 gallon supercell is enough to take a shower. Not near enough for a High Maintenance Wife mind you but enough to take care of business. I use a similar rig on my boat ( now sitting in the barn due to gas prices) to get the water temp of the lake. Try to get one with only one changeable display rather than the triple display as its better to read for that type use.
Woops, missed one thing. Whats the big deal with galvanized anyways? I can't see it burning off at the sort of temps you get in this application. Even if it did wick out a few fumes it wouldn't be nearly enough to be a health problem. Welders do it all the time and it will make you sick temprorarily but it takes long term exposure to do serious health damage. Besides that you have that stove sitting there with the intake only a foot or 2 away, surely much of the fume volume if there is any at all would be consumed by the fire so I myself wouldn't worry about it one bit. The paint will help seal it as well.