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#1
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Unused water heater, leave full or empty?
A friend has a house that came with two identical water
heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... |
#2
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Unused water heater, leave full or empty?
I think you're right about the rust. Can you alternate them, every couple
months? Not sure that makes any sense, but it's a thought. Christopher A. Young Learn more about Jesus www.lds.org .. wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... |
#3
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Unused water heater, leave full or empty?
wrote in message
... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. -- EA |
#4
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Unused water heater, leave full or empty?
"Existential Angst" wrote:
wrote: Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? Drain it fully, blow out any remaining water with compressed air, purge with heated dry air until you get no condensation whatsoever on a chilled mirror and ideally finally purge with dry nitrogen and seal. Most rust inhibitors are to some degree toxic so you dont want to use them in the tank if it will be used for kitchen or bathroom hot water unless they are specifcally marketed as non-toxic for food processig plant. If you water-fill it, ideally use boiled water to reduce dissolved oxygen. -- Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED) ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL |
#5
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Unused water heater, leave full or empty?
On 2/3/2013 9:11 AM, Ian Malcolm wrote:
"Existential Angst" wrote: wrote: Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? Drain it fully, blow out any remaining water with compressed air, purge with heated dry air until you get no condensation whatsoever on a chilled mirror and ideally finally purge with dry nitrogen and seal. Most rust inhibitors are to some degree toxic so you dont want to use them in the tank if it will be used for kitchen or bathroom hot water unless they are specifcally marketed as non-toxic for food processig plant. If you water-fill it, ideally use boiled water to reduce dissolved oxygen. Dissolved oxygen? In H20? -- Robert Allison New Braunfels, TX |
#6
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Unused water heater, leave full or empty?
On Feb 3, 1:05*pm, Robert Allison wrote:
On 2/3/2013 9:11 AM, Ian Malcolm wrote: "Existential Angst" wrote: wrote: Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? Drain it fully, blow out any remaining water with compressed air, purge with heated dry air until you get no condensation whatsoever on a chilled mirror and ideally finally purge with dry nitrogen and seal. Most rust inhibitors are to some degree toxic so you dont want to use them in the tank if it will be used for kitchen or bathroom hot water unless they are specifcally marketed as non-toxic for food processig plant. *If you water-fill it, ideally use boiled water to reduce dissolved oxygen. Dissolved oxygen? *In H20? Well, sure. Fish, after all, couldn't survive without it. But as for drying the tank out with heated dry air and filling it with nitrogen, somehow I don't think that is going to happen..... -- Robert Allison New Braunfels, TX- Hide quoted text - - Show quoted text - |
#7
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Unused water heater, leave full or empty?
" wrote:
But as for drying the tank out with heated dry air and filling it with nitrogen, somehow I don't think that is going to happen..... Not really a problem if you can adapt the nozzle of an electric hot air gun to one of the ports of the tank and leave another port open. Don't turn it up to its full paint-stripping setting! ;-) I *KNOW* the dry nitrogen is unlikely to be convenient. . . . -- Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED) ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL |
#8
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Unused water heater, leave full or empty?
More accurately, dissolved air.
Christopher A. Young Learn more about Jesus www.lds.org .. "Robert Allison" wrote in message eb.com... On 2/3/2013 9:11 AM, Ian Malcolm wrote: Most rust inhibitors are to some degree toxic so you dont want to use them in the tank if it will be used for kitchen or bathroom hot water unless they are specifcally marketed as non-toxic for food processig plant. If you water-fill it, ideally use boiled water to reduce dissolved oxygen. Dissolved oxygen? In H20? -- Robert Allison New Braunfels, TX |
#9
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Unused water heater, leave full or empty?
"Robert Allison" wrote in message
Dissolved oxygen? In H20? Robert Allison New Braunfels, TX "Stormin Mormon" wrote in message ... More accurately, dissolved air. Christopher A. Young Draw some hot water into a glass. The slowly disappearing milkiness is tiny bubbles of air that comes out of solution when the pressure is removed. Cold water holds more dissolved air than hot water. |
#10
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Unused water heater, leave full or empty?
"Existential Angst" wrote in message
... Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... EA I acquired a serviceable used electric water heater from a remodelling project and mounted it horizontally in a close-fitted greenhouse box as an unpressurized solar batch heater. After about 3-4 years the tank started to spring small leaks on the cold bottom side which I patched until I couldn't keep up. Anything you put in it, like RV antifreeze, will be very tricky to completely remove because the tanks are so hard to handle. The best way I found was hanging it horizontal by a choker sling with the heater holes on the bottom and spraying a hose in through them, but I doubt I directly rinsed even half of the surface area and couldn't touch anything absorbed into the crud in the vee groove around the concave bottom end. Since the tank wasn't connected to my plumbing and the water was only for laundry or car washing a little soap or LPS-3 in it didn't matter. They can be difficult/expensive to dispose of unless you have a friend in the scrap business. I traded two heaters for an old farm wagon front axle. |
#11
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Unused water heater, leave full or empty?
On Feb 3, 9:53*am, "Existential Angst" wrote:
wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. *He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. *This was several years ago. *The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. *The rcm peeple should have some insights into both Qs. -- EA- Hide quoted text - - Show quoted text - The issue of series vs parallel connection of dual water heaters has been debated here a few times. AFAIK, there wasn't any overwhelming advantage to either. One difference would be that in parallel as soon as you've drawn some amount of water, they are BOTH going to fire, so you're getting 2X the heating sooner. With them in series, the upstream one isn't going to fire until a lot of the water has been drawn. On the other hand, with them in series there is going to be more hot water at a higher temp for longer due to cold water not coming directly into the upstream tank. In the grand scheme of things, it probably doesn't make much difference. |
#12
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Unused water heater, leave full or empty?
"Existential Angst" wrote in message ... wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp. |
#13
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Unused water heater, leave full or empty?
In rec.crafts.metalworking PrecisionmachinisT wrote:
"Existential Angst" wrote in message ... wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp. Other than skinning a trashed water heater, most of which are leaking anyways, are there purpose made tanks for this use? I've been looking for something along these lines to get "room temp" water for a photographic darkroom where there's extended draw of water. Anything homemade looking and attached to the water lines before the backflow preventers might draw attention from the landlord or inspectors. Just adding a waterheater-ish tank before the existing one would be the easiest, as long as it draw no attention and won't burst over the weekend. |
#14
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Unused water heater, leave full or empty?
On Mon, 4 Feb 2013 19:38:59 +0000 (UTC), Cydrome Leader
wrote: In rec.crafts.metalworking PrecisionmachinisT wrote: "Existential Angst" wrote in message ... wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp. Other than skinning a trashed water heater, most of which are leaking anyways, are there purpose made tanks for this use? I've been looking for something along these lines to get "room temp" water for a photographic darkroom where there's extended draw of water. Anything homemade looking and attached to the water lines before the backflow preventers might draw attention from the landlord or inspectors. Just adding a waterheater-ish tank before the existing one would be the easiest, as long as it draw no attention and won't burst over the weekend. You could get a water heater that's being replaced before it bursts. Just add a valve on its inlet side so there is no pressure on it when it's not in use. It should last a long time without constant pressure on it. If it does leak, you're right there. |
#15
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Unused water heater, leave full or empty?
"Cydrome Leader" wrote in message
... In rec.crafts.metalworking PrecisionmachinisT wrote: "Existential Angst" wrote in message ... wrote in message ... .......... Other than skinning a trashed water heater, most of which are leaking anyways, are there purpose made tanks for this use? I've been looking for something along these lines to get "room temp" water for a photographic darkroom where there's extended draw of water. I got nowhere by asking a plumbing supply house this question. The owner thought it was a good idea but couldn't find an inexpensive tank in his catalog. The two best possibilities I can think of are a bladder tank for a well and a water softener tank. http://www.wwpp.com/products/flexcon...sure-tanks.htm http://www.discoun****ersofteners.co...sin-tanks.html Though they won't take much pressure, a blue plastic 55 gallon barrel is a cheap option for the rinse water. I have one hung high in a shed at the back of my large lot for brush fire protection. The larger bung plug has a knockout for 3/4" NPT. ~5 PSI bulges the bottom enough to make it tip over. jsw |
#16
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Unused water heater, leave full or empty?
On Mon, 4 Feb 2013 19:38:59 +0000 (UTC)
Cydrome Leader wrote: snip Other than skinning a trashed water heater, most of which are leaking anyways, are there purpose made tanks for this use? I've been looking for something along these lines to get "room temp" water for a photographic darkroom where there's extended draw of water. snip We have something like 150 ft of 1 inch black plastic water pipe in a coil (maybe 3 ft in diameter), hanging on the wall downstairs before the toilet supply. Does wonders in the summer time when they would sweat otherwise. Used to have a galvanized water pressure tank for same years ago but due to hard water it developed a lot of sediment. So far the coiled up pipe seems to be working okay, maybe 20 years now. -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
#17
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Unused water heater, leave full or empty?
"Leon Fisk" wrote in message
... On Mon, 4 Feb 2013 19:38:59 +0000 (UTC) Cydrome Leader wrote: snip Other than skinning a trashed water heater, most of which are leaking anyways, are there purpose made tanks for this use? I've been looking for something along these lines to get "room temp" water for a photographic darkroom where there's extended draw of water. snip We have something like 150 ft of 1 inch black plastic water pipe in a coil (maybe 3 ft in diameter), hanging on the wall downstairs before the toilet supply. Does wonders in the summer time when they would sweat otherwise. Used to have a galvanized water pressure tank for same years ago but due to hard water it developed a lot of sediment. So far the coiled up pipe seems to be working okay, maybe 20 years now. Putting that coil outside in the sun would be even better, in the summer. Solar on the cheap.... Or in a black box, covered by glass..... really good solar, on the cheap.... Toward the purpose-made tank Q: An old compressor tank, 30-50 gals? Or smaller ones in series? Even propane? Altho the fittings on propane are an experience to remove.... May want to paint the interior first. -- EA -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
#18
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Unused water heater, leave full or empty?
PrecisionmachinisT wrote:
"Existential Angst" wrote in message ... wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp. I am not sure, but I think that technically speaking that approach won't save any money on energy costs. The reason is that for the water in the first tank to be brought up to room temperature, it needs to draw its heat energy from the room. So, it will cost that much more to heat the room because some of the room heat is going toward heating the water in the first tank. In other words, there is no free heat -- it either gets its heat from being heated by at working hot water tank, or it gets its heat from the room and that heat energy needs to be replaced by the heating system for the room. |
#19
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Unused water heater, leave full or empty?
On Monday, February 4, 2013 2:56:03 PM UTC-5, TomR wrote:
PrecisionmachinisT wrote: "Existential Angst" wrote in message ... wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp. I am not sure, but I think that technically speaking that approach won't save any money on energy costs. The reason is that for the water in the first tank to be brought up to room temperature, it needs to draw its heat energy from the room. So, it will cost that much more to heat the room because some of the room heat is going toward heating the water in the first tank. In other words, there is no free heat -- it either gets its heat from being heated by at working hot water tank, or it gets its heat from the room and that heat energy needs to be replaced by the heating system for the room. I believe he said "reduce summer time costs". And it does do that since ground water and city water are usually a lot cooler than summer air temps. I run two wh in series with the 1st one on a 30amp switch in the hall. When I anticipate guests or otherwise needing extra hw I just turn it on. |
#20
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Unused water heater, leave full or empty?
On Feb 4, 3:53*pm, jamesgang wrote:
On Monday, February 4, 2013 2:56:03 PM UTC-5, TomR wrote: PrecisionmachinisT wrote: "Existential Angst" wrote in message ... wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp. I am not sure, but I think that technically speaking that approach won't save any money on energy costs. The reason is that for the water in the first tank to be brought up to room temperature, it needs to draw its heat energy from the room. So, it will cost that much more to heat the room because some of the room heat is going toward heating the water in the first tank. In other words, there is no free heat -- it either gets its heat from being heated by at working hot water tank, or it gets its heat from the room and that heat energy needs to be replaced by the heating system for the room. I believe he said "reduce summer time costs". *And it does do that since ground water and city water are usually a lot cooler than summer air temps. But the proposed tank isn't going to be sitting outside in the summer air. It's typically going to be in an unfinished basement, or inside the living space. So, if you take city water at 45F in winter and get it up to 60F in a basement, I guess it will help some, but doubt it's worth the trouble. In summer it would make even less difference, because the incoming city water is going to be closer to basement or living space temp. For the guy asking if there are tanks suitable for the purpose, that would seem to be any water tank that's suited for a well pump. Preferably without a bladder inside, but that could be removed. Might find one on craigslist.... I run two wh in series with the 1st one on a 30amp switch in the hall. *When I anticipate guests or otherwise needing extra hw I just turn it on.. |
#21
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Unused water heater, leave full or empty?
jamesgang wrote:
I believe he said "reduce summer time costs". And it does do that since ground water and city water are usually a lot cooler than summer air temps. You are correct. He wrote, "Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp." I didn't catch that part - that he meant in the summertime with the AC on etc. |
#22
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Unused water heater, leave full or empty?
"jamesgang" wrote in message
... On Monday, February 4, 2013 2:56:03 PM UTC-5, TomR wrote: PrecisionmachinisT wrote: "Existential Angst" wrote in message ... wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp. I am not sure, but I think that technically speaking that approach won't save any money on energy costs. The reason is that for the water in the first tank to be brought up to room temperature, it needs to draw its heat energy from the room. So, it will cost that much more to heat the room because some of the room heat is going toward heating the water in the first tank. In other words, there is no free heat -- it either gets its heat from being heated by at working hot water tank, or it gets its heat from the room and that heat energy needs to be replaced by the heating system for the room. I believe he said "reduce summer time costs". And it does do that since ground water and city water are usually a lot cooler than summer air temps. I run two wh in series with the 1st one on a 30amp switch in the hall. When I anticipate guests or otherwise needing extra hw I just turn it on. ============================================== Staged water heating.... what a neat idear!! -- EA |
#23
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Unused water heater, leave full or empty?
"TomR" wrote in message
... I am not sure, but I think that technically speaking that approach won't save any money on energy costs. The reason is that for the water in the first tank to be brought up to room temperature, it needs to draw its heat energy from the room. So, it will cost that much more to heat the room because some of the room heat is going toward heating the water in the first tank. In other words, there is no free heat -- it either gets its heat from being heated by at working hot water tank, or it gets its heat from the room and that heat energy needs to be replaced by the heating system for the room. |
#24
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Unused water heater, leave full or empty?
"TomR" wrote in message ... PrecisionmachinisT wrote: "Existential Angst" wrote in message ... wrote in message ... A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... Fill it with water, add a rust inhibitor? As an aside, shouldn't two water heaters be hooked up in series? Been meaning to post that to the group. The rcm peeple should have some insights into both Qs. Having a second tank that's unpowered, uninsulated, and plumbed in series so that cold water passes through it first will reduce summertime AC and water heating costs by naturally warming the inlet water up to room temp. I am not sure, but I think that technically speaking that approach won't save any money on energy costs. The reason is that for the water in the first tank to be brought up to room temperature, it needs to draw its heat energy from the room. So, it will cost that much more to heat the room Which is why I said that energy savings occur during summertime through a reduction in AC usage. because some of the room heat is going toward heating the water in the first tank. In other words, there is no free heat -- it either gets its heat from being heated by at working hot water tank, or it gets its heat from the room and that heat energy needs to be replaced by the heating system for the room. |
#25
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Unused water heater, leave full or empty?
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#26
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Unused water heater, leave full or empty?
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#27
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Unused water heater, leave full or empty?
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#28
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Unused water heater, leave full or empty?
On Feb 3, 10:55*pm, "Bob F" wrote:
wrote: A friend has a house that came with two identical water heaters hooked up in parallel. *He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. *This was several years ago. *The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... 2 thoughts" Hot water furnaces and their piping don't corrode because the O2 that rusts them gets used up, and the rusting stops, as I understand it. As long as the anode is good, rust shouldn't happen, right?- Hide quoted text - - Show quoted text - Rust and what the anode is there for are two seperate things. Rust involves oxygen combining with iron. The sacrificial anode involves two dissimilar metals in an electrolyte. Think about boats. They use a similar approach, with zinc being used as the sacrificial anode to protect the underwater metals. Zinc is more reactive than bronze, stainless steel, etc so it comes off instead. |
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Unused water heater, leave full or empty?
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... On Feb 3, 10:55 pm, "Bob F" wrote: wrote: A friend has a house that came with two identical water heaters hooked up in parallel. He doesn't need all the capacity, so we turned one of them off and turned off the water going into it. This was several years ago. The water heater was about 4 years old at the time, it's now 7 years old. Given that a tank has already had some service, what would you guys do to try to keep the spare tank available for as long as possible? Leave it full of water? Drain it? My thought was that draining it would be worse, because allowing air in, it would rust....... 2 thoughts" Hot water furnaces and their piping don't corrode because the O2 that rusts them gets used up, and the rusting stops, as I understand it. As long as the anode is good, rust shouldn't happen, right?- Hide quoted text - - Show quoted text - Rust and what the anode is there for are two seperate things. Rust involves oxygen combining with iron. The sacrificial anode involves two dissimilar metals in an electrolyte ================================================== == A good observation, BUT the (dissolved) oxygen would/should combine with sacrificial magnesium, zinc etc first, as well. Magnesium, zinc, alum appear not to "rust" because the nature of those oxides is *mechanically* stable, whereas iron oxides are not, constantly exposing more fresh iron, ergo a deterioating process. -- EA . Think about boats. They use a similar approach, with zinc being used as the sacrificial anode to protect the underwater metals. Zinc is more reactive than bronze, stainless steel, etc so it comes off instead. |
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